iLib08 - CitaviiLib08 - CitaviiLib08 - CitaviiLib08 - Citavi

Accornero, N.; Berardelli, A.; Fabiano, F.; Inghilleri, M.; Taverniti, L. (1983): [Perception of light modulation]. In:Bollettino della Società italiana di biologia sperimentale, Jg. 59, H. 12, S. 1980–1983.Abstract A simple method for testing visual sensitivity to flickering light sources is proposed.

The method employs a triangular function generator, which modulates theluminance of a chromatic light source. Amplitude and frequency of the triangularpattern are adjusted until the subject perceives a periodic variation of luminance. Innormal subjects the maximum sensitivity was found at a frequency modulation of 5-10 Hz. In multiple sclerosis patients the method proved to be more accurate thanflicker fusion frequency in revealing subclinical damage of the visual pathway.

Schlagwörter Flicker Fusionphysiology; Humans; Multiple Sclerosisphysiopathology; PhoticStimulation; Visual Perceptionphysiology

Anderson, A. J.; Vingrys, A. J. (2001): Multiple processes mediate flicker sensitivity. In: Vision research, Jg. 41,H. 19, S. 2449–2455.Abstract By systematically manipulating the luminance of a flickering spot and the area

immediately surrounding it, we investigated why thresholds from flickering stimulithat cause a change in average luminance are elevated relative to those fromstimuli with no luminance change. Threshold elevation resulted from local lightadaptation and from temporal-frequency-specific interactions between the spot andits surround: at low frequencies, the contrast between the spot and the surroundelevated thresholds, whereas at high frequencies, dark adaptation within thesurround elevated thresholds. Our findings suggest that two common ways ofdetermining temporal sensitivity may give markedly different outcomes.

Schlagwörter Adaptation, Ocularphysiology; Adult; Analysis of Variance; ContrastSensitivityphysiology; Humans; Lighting; Sensory Thresholdsphysiology; TimeFactors

Anderson, D. J.; Legg, N. J.; Ridout, D. A. (1997): Preliminary trial of photic stimulation for premenstrualsyndrome. In: Journal of obstetrics and gynaecology : the journal of the Institute of Obstetrics and Gynaecology,Jg. 17, H. 1, S. 76–79. Online verfügbar unter doi:10.1080/01443619750114211.Abstract In an open study 17 women with confirmed, severe and long-standing premenstrual

syndrome used photic stimulation with a flickering red light, every day for up to fourmenstrual cycles. At the end of treatment prospectively recorded median lutealsymptom scores were reduced by 76% (95% confidence interval 54-93, P < 0.001),with clinically and statistically significant reductions for depression, anxiety, affectivelability, irritability, poor concentration, fatigue, food cravings, bloating and breastpain. Twelve of the 17 patients (71%) no longer had the premenstrual syndrome.One patient failed to improve. One patient withdrew because of worseningpremenstrual depression, but photic stimulation was otherwise well tolerated. Theimprovement is greater than that reported for relaxation or in open studies offluoxetine, and much more than historical placebo rates. Photic stimulation may bea useful treatment for the premenstrual syndrome, and by its suggested action oncircadian rhythms may have wider therapeutic applications.

Becker, Cordula; Elliott, Mark A. (2006): Flicker-induced color and form: interdependencies and relation tostimulation frequency and phase. In: Consciousness and cognition, Jg. 15, H. 1, S. 175–196. Online verfügbarunter doi:10.1016/j.concog.2005.05.004.Abstract Our understanding of human visual perception generally rests on the assumption

that conscious visual states represent the interaction of spatial structures in theenvironment and our nervous system. This assumption is questioned bycircumstances where conscious visual states can be triggered by externalstimulation which is not primarily spatially defined. Here, subjective colors andforms are evoked by flickering light while the precise nature of those experiencesvaries over flicker frequency and phase. What's more, the occurrence of onesubjective experience appears to be associated with the occurrence of others.

iLib08 - CitaviiLib08 - CitaviiLib08 - CitaviiLib08 - CitaviWhile these data indicate that conscious visual experience may be evoked directlyby particular variations in the flow of spatially unstructured light over time, it must beassumed that the systems responsible are essentially temporal in character andcapable of representing a variety of visual forms and colors, coded in differentfrequencies or at different phases of the same processing rhythm.

Schlagwörter Adult; Color Perception; Humans; Light; Male; Models, Psychological; PhysicalStimulationmethods; Time Factors; Visual Perception

Bobon, D. P.; Lecoq, A.; Frenckell, R. von; Mormont, I.; Lavergne, G.; Lottin, T.: [Critical flicker fusion frequencyin psychopathology and psychopharmacology. Review of the literature]. In: Acta psychiatrica Belgica, Jg. 82, H.1, S. 7–112.Abstract As far back as the second century, Ptolemy reported the apparent immobility of

wheel radius at a certain speed. The psychophysical laws of this flicker fusionphenomenon related to the frequency of the light stimulus were established in 1834-1835 by the Englishman Talbot and by the Belgian Plateau, whose thesis in Liège isdescribed as a landmark in the field. CFF is more a measurement of cortical arousalthan of visual functions. In psychophysiology, CFF underwent periods of successand oblivion, at the mercy of researcher's enthusiasm or disappointment. At the turnof this century, Pierre Janet measured CFF in the laboratory of physiology of theSalpêtrière Hospital and demonstrated its decrease 'in hysteria, in states ofdepression, of lowered tension'. All reviewers of CFF literature have overlookedthese observations, reported by Henri Piéron in the 'Melanges dedicated toMonsieur Pierre Janet'. When CFF falls into disgrace, it is because of the variabilityof its results, due to differences in apparatus and designs of the trials as well as thegreat number and the intrication of the variables which modify CFF thresholds,among them the nonsensory variables. When CFF is reappraised, as it has beenthe case in psychopharmacology in recent years, the reason is that it represents abrief, easy and economical measure of vigilance which, under certain conditions,seems to be also reliable, valid and sensitive. In the present monograph, the first inFrench on CFF, the authors try to analyze the most important contributions of theliterature from the standpoint of the most relevant variables: characteristics of thestimulus (light intensity, wave form, wavelength, light-dark-ratio, diameter of theflickering point), test procedure (light vs. dark adaptation, visual angle, continuousvs. discontinuous presentation, monocular vs. binocular vision), influence of variousphysiological or psychological conditions (pupillary diameter, age, training, IQ;anxiety, depression, motivation etc.). The authors summarize the prerequisite forCFF to measure vigilance or aging in psychopharmacological research. The presentMonograph is dedicated to the authors' 'Maîtres', who recently became EmeritusProfessors, namely the ophthalmologist Roger Weekers, the pioneer of the clinicalapplication of CFF in Belgium, and the psychiatrist Jean Bobon, who pioneeredclinical psychopharmacology in Belgium.

Schlagwörter Adaptation, Oculardrug effects; Adolescent; Adult; Age Factors; Child; Dominance,Cerebralphysiology; Female; Flicker Fusiondrug effectsphysiology; Humans;Intelligencedrug effects; Male; Mental Disorderspsychology; Motivationdrug effects;Photic Stimulation; Psychotropic Drugspharmacology; Sensory Thresholds; VisualFieldsdrug effects; Visual Pathwaysphysiology

Boshouwers, F. M.; Nicaise, E. (1992): Responses of broiler chickens to high-frequency and low-frequencyfluorescent light. In: British poultry science, Jg. 33, H. 4, S. 711–717.Abstract 1. The influence of the flicker frequency on physical activity and energy expenditure

of broilers was studied using commercially available high-frequency (HF) and low-frequency (LF) fluorescent lamps in a 23L:1D lighting schedule. 2. Broilers werereared under and adapted to HF. They were alternately subjected to HF and LFduring measurement of activity and energy expenditure. 3. In comparison with HF,LF inhibited activity (number and intensity of movements), but did not influenceenergy expenditure. 4. It was concluded that the 100 Hz flickering of low-frequency

iLib08 - CitaviiLib08 - CitaviiLib08 - CitaviiLib08 - Citavilight is detected by broilers and has measurable behavioural effects upon them. 5.The results were discussed in relation to current knowledge of human and birds'critical flicker frequency and perception.

Schlagwörter Animals; Chickensphysiology; Flicker Fusionphysiology; Lightingmethods; MotorActivityphysiology

Buerk, D. G.; Riva, C. E.; Cranstoun, S. D. (1995): Frequency and luminance-dependent blood flow and K+ ionchanges during flicker stimuli in cat optic nerve head. In: Investigative ophthalmology & visual science, Jg. 36,H. 11, S. 2216–2227.Abstract PURPOSE. The purpose of this study was to investigate whether blood flow in the

cat optic nerve head (ONH) is related to increased neuronal activity elicited bydiffuse luminance flickering light stimulation. METHODS. ONH blood flow wasmeasured by laser Doppler flowmetry in anesthetized cats during 1 to 3 minutes offlickering light stimulation at controlled luminance and frequency (n = 227measurements in 18 cats) using either a conventional visual stimulator (repetitiveshort flashes) or a sinusoidally varying light stimulator. Potassium ion concentration([K+]) changes in the vitreous humor immediately in front of the optic disk weremeasured with neutral carrier K+ ionophore liquid membrane microelectrodes.Effects of varying flicker frequency (2 to 80 Hz) at constant luminance werequantified. Effects of luminance were quantified by varying the modulation depth ofthe stimulus at constant frequency. RESULTS. Both ONH blood flow and [K+]increased during flicker stimulus with an average slope of 0.305% +/- 0.064%(SE)/microM [K+] (257 measurements in 18 cats). The peak ONH blood flowincrease was 59% +/- 11% above baseline at 33.3 +/- 3.1 Hz. The peak [K+]increase was 188 +/- 42 microM above baseline at 38.3 +/- 3.3 Hz. Both ONH bloodflow and [K+] changes had similar bandpass characteristics with frequency, firstincreasing, then dropping off at higher frequencies (122 measurements in 10 cats).Both frequency responses were described by power law functions (y = af").Luminance responses for both ONH blood flow and [K+] changes could be fit by amodified Hill model and were 50% of maximum at light modulation depths of 21.2%+/- 4.6% and 22.5% +/- 3.7%, respectively (53 measurements in 5 cats).CONCLUSIONS. Increases in ONH blood flow were correlated with changes in[K+]. Both responses were remarkably similar, with no significant differences in thefrequency for peak responses in ONH blood flow or [K+], in low- and high-frequencypower law exponents of the two responses, or in the 50% response to lightmodulation. The results are consistent with close coupling of neuronal activity andONH blood flow.

Schlagwörter Animals; Biological Transport, Active; Blood Flow Velocityphysiology; Cats;Homeostasis; Laser-Doppler Flowmetry; Microelectrodes; Optic Diskblood supply;Optic Nervephysiology; Photic Stimulation; Potassiummetabolism; VitreousBodymetabolism

Bush, R. A.; Sieving, P. A. (1996): Inner retinal contributions to the primate photopic fast flickerelectroretinogram. In: Journal of the Optical Society of America. A, Optics, image science, and vision, Jg. 13, H.3, S. 557–565.Abstract The primate electroretinogram (ERG) recorded at the cornea in response to fast

flickering light is thought to reflect primarily the cone photoreceptor potential. Weinvestigated the origin of the photopic 33-Hz corneal flicker ERG to square-waveand photostrobe flashes by recording in the monkey before and after blockingpostsynaptic responses with intravitreal injections of 2-amino-4-phosphonobutyricacid and/or cis-2,3-piperidiendicarboxylic acid or sodium aspartate. Blockingpostsynaptic ON or OFF responses produced effects on the timing and thewaveform of the 33-Hz flicker ERG similar to changes in the b and the d waves inthe corneal single-flash ERG. When all the ERG waves of postsynaptic origin in theflash ERG were abolished the flicker response was greatly suppressed, suggestingthe postsynaptic cells producing the b and the d waves make major contributions to

iLib08 - CitaviiLib08 - CitaviiLib08 - CitaviiLib08 - Citavithe photopic fast flicker ERG.

Schlagwörter Aminobutyric Acidspharmacology; Animals; Aspartic Acidpharmacology;Corneaphysiologyradiation effects; Electroretinography; Injections; Macacafascicularisphysiology; Macaca mulattaphysiology; Photic Stimulationmethods;Pipecolic Acidspharmacology; Retinaphysiology; Synapsesdrug effects; VitreousBody

Carmel, David; Saker, Pascal; Rees, Geraint; Lavie, Nilli (2007): Perceptual load modulates conscious flickerperception. In: Journal of vision, Jg. 7, H. 14, S. 14.1-13. Online verfügbar unter doi:10.1167/7.14.14.Abstract Subjective visual experience depends not only on the spatial arrangement of the

environment, but also on the temporal pattern of stimulation. For example, flickeringand steady light presented in the same location evoke a very different perceptualexperience due to their different temporal patterns. Here, we examined whether theavailability of processing resources affected the temporal resolution of consciousflicker perception--the ability to distinguish rapid changes in light intensity, detectingvisual temporal patterns. Participants detected flicker in a fixated LED that flickeredat or around the individually adjusted critical flicker fusion (CFF) threshold whilesearching for a target letter presented in the periphery either on its own (lowperceptual load) or among other letters (high load). Physically identical flickeringstimuli were more likely to be perceived as "fused" under high (compared to low)load in the peripheral letter search. Furthermore, psychophysical measures showeda reduction in flicker detection sensitivity under high perceptual load. These resultscould not be due to criterion or stimulus prioritization differences or to differentiallikelihood of forgetting the correct response under different load conditions. Thesefindings demonstrate that perceptual load influences conscious perception oftemporal patterns.

Schlagwörter Adult; Attentionphysiology; Female; Flicker Fusion; Humans; Light; Male;Periodicity; Psychophysics; Sensory Thresholds; Time Factors; VisualFieldsphysiology; Visual Perceptionphysiology

Chang, Y.; Burns, S. A.; Kreitz, M. R. (1993): Red-green flicker photometry and nonlinearities in the flickerelectroretinogram. In: Journal of the Optical Society of America. A, Optics and image science, Jg. 10, H. 6, S.1413–1422.Abstract We investigated whether responses from different cone classes are combined

before or after the nonlinearity that is responsible for generating nonlinear responsecomponents of the flicker electroretinogram (ERG). We measured the nonlinearresponse of the retina while systematically varying the modulation in the long-wavelength-sensitive and middle-wavelength-sensitive cones by changing theproportions of flickering 633- and 543-nm lights that compose a sum-of-sinusoidstemporal waveform. We found that at high temporal frequencies the ERGresponses are best accounted for by a model in which the principal retinalnonlinearity is located before the convergence of signals from the two cone classes.At low temporal frequencies the ERG signal is dominated by cone-antagonisticresponses. At frequencies of 30 Hz and higher, the flicker ERG and psychophysicalflicker photometry give similar estimates of the relative proportions of long- andmiddle-wavelength-sensitive cones. The ERG photometric null is frequencydependent, whereas the psychophysically determined ratio is much less sensitive tochanges in frequency.

Schlagwörter Color Perceptionphysiology; Electroretinography; Humans; Light; Male; Photometry;Photoreceptor Cellsphysiology; Psychophysics; Sensory Thresholds

Colman, R. S.; Frankel, F.; Ritvo, E.; Freeman, B. J. (1976): The effects of fluorescent and incandescentillumination upon repetitive behaviors in autistic children. In: Journal of autism and childhood schizophrenia, Jg.6, H. 2, S. 157–162.Abstract Repetitive behaviors of six autistic children were observed under two conditions of

background illumination. During two sessions, the room was illuminated by

iLib08 - CitaviiLib08 - CitaviiLib08 - CitaviiLib08 - Citavifluorescent light and during two other sessions, by equal intensity incandescentlight. Subjects spent significantly more time engaged in repetitive behavior underfluorescent light. Previous research suggested that these findings were related tothe flickering nature of fluorescent ilumination. Practical and theoretical implicationswere discussed. Further experimentation was suggested to assess relationshipsbetween flickering illumination and arousal.

Schlagwörter Arousal; Autistic Disorderdiagnosis; Behavior; Child, Preschool; Humans;Intelligence Tests; Lighting; Male; Reinforcement (Psychology); StereotypedBehavior

Corwin, T. R.; Dunlap, W. P. (1987): The shape of the high frequency flicker sensitivity curve. In: Visionresearch, Jg. 27, H. 12, S. 2119–2123.Abstract For a light flickering with a modulation amplitude delta L, there is a single frequency

f above which the light appears steady (fused). The relationship between delta Land f has been measured often under a variety of conditions, but its mathematicalform is disputed. Three candidate functions have been proposed: (1) log delta Lalpha f [Ferry-Porter law], (2) log delta L alpha f1/2 [diffusion model], and (3) logdelta L alpha log f [cascaded integrator model]. Although all three functions roughlyfit flicker fusion data (after appropriate linear transformation), they differ incurvature. We compared these functions using the general expression (4) log deltaL alpha f lambda, where lambda denotes a curvature parameter. Functions (1)-(3)are special cases of (4) with lambda = 1, 0.5, and 0 respectively. When applied to35 sets of flicker fusion data, the mean values of the best fitting lambda for eachdata-set was 0.919 (95% confidence interval 1.027 to 0.812). We conclude that theFerry-Porter law describes most data better than a diffusion model, and that anintegrator model deviates consistently in every case.

Schlagwörter Flicker Fusionphysiology; Humans; Mathematics; Models, Neurological

Crewther, Sheila G.; Barutchu, Ayla; Murphy, Melanie J.; Crewther, David P. (2006): Low frequency temporalmodulation of light promotes a myopic shift in refractive compensation to all spectacle lenses. In: Experimentaleye research, Jg. 83, H. 2, S. 322–328. Online verfügbar unter doi:10.1016/j.exer.2005.12.016.Abstract Emmetropization, the process by which ocular growth of young animals adapts to

ensure focussed retinal images, can be disrupted by high frequency flicker, causinga hypermetropic shift. Emmetropization can also be disrupted differentially, in a signdependent manner, by pharmacological alteration of the balance of activation of theON and OFF retinal sub-systems in normal light or by rearing in an environmentwith a moving spatiotemporally varied diamond pattern (yielding local sawtoothillumination on the retina). Thus the aim of this experiment was to determinewhether low frequency temporal modulation alone was sufficient to cause defocussign-dependent interference with compensation. Chicks were reared for 6 or 7 dayswith monocular +/-10 D, 0 D, or No Lenses in a 12h light/dark cycle. Luminance ofthe environment was temporally modulated during the light cycle with a non-squarewave profile pulse of 250 msec duration, with the illumination fluctuating between1.5 and 180 lux at 1 Hz, 2 Hz, 4 Hz or with no flicker (0 Hz-180 lux). Final refractivestate and ocular dimensions, measured using retinoscopy and A-scanultrasonography, demonstrated that in the absence of temporal luminancemodulation (0 Hz), chicks compensated to induced defocus in the expected sign-dependent manner. However, under 1, 2 and 4 Hz flickering light conditions, therewas an overall myopic offset of approximately 6D across lens groups with refractivecompensation to positive lenses more strongly inhibited. This myopic offset wasreflected by increases in the depth of both vitreous and anterior chambers.However, luminance modulation had no effect on refraction or ocular parameters inthe No Lens conditions. This is a hitherto unreported strong interaction betweenlens wear and low frequency temporally modulated light, with the refractivecompensation mechanism being overridden by a generalized myopic shift.

Schlagwörter Accommodation, Ocularphysiology; Adaptation, Ocularphysiology; Animals;

iLib08 - CitaviiLib08 - CitaviiLib08 - CitaviiLib08 - CitaviChickens; Contact Lenses; Eyeglasses; Light; Male; Myopiaphysiopathology; PhoticStimulationmethods; Refraction, Ocularphysiology; Time Factors

Delorme, A.; Frigon, J. Y.; Lavoie, G. (1976): [The illusion of movement in flickering light: the effect of thefrequency of flicker and the intensity of the light]. In: Canadian journal of psychology, Jg. 30, H. 2, S. 115–121.Schlagwörter Female; Flicker Fusion; Humans; Illusions; Lighting; Male; Motion Perception;

Optical Illusions; Visual Perception

Dezawa, M.; Mo, X.; Oshitari, T.; Takano, M.; Meyer-Rochow, V. B.; Sawada, H.; Eguchi, E. (2001): Effects oflight and darkness on cell deaths in damaged retinal ganglion cells of the carp retina. In: Acta neurobiologiaeexperimentalis, Jg. 61, H. 2, S. 85–91.Abstract Effects of light and darkness on the apoptosis of retinal ganglion cells (RGCs) in

young carp were measured by TUNEL method after transection of the optic nerve.Following the operation, the fish were kept under one of four regimens; constantdarkness (DD), constant light (LL), 12 hr light and 12 hr dark (LD) and 3 hr offlickering light followed by 21 hr in the dark (FL). On day 3, the highest ratio ofapoptotic RGCs was seen under conditions of DD, followed by LL, LD, and FL. Onday 6, the percentages of apoptotic RGCs were lower under every experimentalcondition than what they had been earlier on day 3, but the same ranking order wasmaintained. Immunohistochemically it could be shown that phosphorylated ERKswere more intensively localized in FL rather than DD retinas. The results suggestthat illumination regimens, and in particular cyclic diurnal light/dark changes, havean influence on the degree of apoptosis of damaged RGCs, and that inhibition ofapoptosis is correlated with the higher expression of phosphorylated ERKs.

Schlagwörter Adaptation, Ocularphysiology; Animals; Apoptosisphysiology; Carps; DarkAdaptationphysiology; Darkness; Fluorescent Antibody Technique; In Situ Nick-EndLabeling; Mitogen-Activated Protein Kinasesmetabolism; Optic NerveInjuriespathologyphysiopathology; Photic Stimulation; Retinal GanglionCellsenzymologypathology

Diamond, A. L. (1979): Microsecond sensitivity of the human visual system to irregular flicker. In: Science (NewYork, N.Y.), Jg. 206, H. 4419, S. 708–710.Abstract A flickering light presented to the eye produces a small alternating voltage at the

scalp of a subject. This alternating voltage indicates the following response of thebrain to the flicker. If every other flash in the flicker is displaced temporally by aslittle as 30 microseconds, an asymmetry appears in the brain's alternating voltage.The results suggest an underlying mechanism that may enhance visual detection ofhigh-frequency flicker.

Schlagwörter Evoked Potentials; Flicker Fusionphysiology; Humans; Time Factors; Vision, Ocular

Dixon, Bernard (2004): Green light flickering for the UK's first GM crop. In: Current biology : CB, Jg. 14, H. 6, S.R213-4. Online verfügbar unter doi:10.1016/j.cub.2004.02.043.Schlagwörter Government Regulation; Great Britain; Journalism; Plants, Genetically Modified;

Zea mays

Dong, C. J.; McReynolds, J. S. (1992): Comparison of the effects of flickering and steady light on dopaminerelease and horizontal cell coupling in the mudpuppy retina. In: Journal of neurophysiology, Jg. 67, H. 2, S.364–372.Abstract 1. The effects of flickering adapting illumination (repetitive flashes) on horizontal cell

responses to illumination of the center and surround portions of the receptive fieldwere compared with those of steady adapting illumination in dark-adaptedmudpuppy retinas. 2. Exposure to flickering adapting light caused an increase inamplitude of responses to small spots in the receptive-field center and a decreasein the response to a concentric annulus. This is interpreted as due to an increase incoupling resistance between horizontal cells. 3. The uncoupling effect of flickeringadapting light was no greater than that of the same quantity of steady adapting light

iLib08 - CitaviiLib08 - CitaviiLib08 - CitaviiLib08 - Citaviat the same intensity, even when the rate of flickering was varied by a factor of 10.4. The uncoupling effect of flickering light was blocked by the dopamine antagonistsfluphenazine and SCH23390, indicating that it is mediated by dopamine release. 5.The uncoupling effect of flickering light was also blocked in the presence of 2-amino-4-phosphonobutyrate (APB), which prevents light responses of on-center butnot off-center bipolar cells, suggesting that flickering light increases dopaminerelease via the on-pathway. 6. The gamma-aminobutyric acid (GABA) antagonistbicuculline had an uncoupling effect similar to that of adapting illumination. Thiseffect was blocked by dopamine antagonists, indicating that there is tonic GABA-mediated inhibition of dopamine release in mudpuppy retina similar to thatpreviously reported by others in fish and turtle retinas. 7. The uncoupling effect ofbicuculline was not reversed by APB. However, APB alone caused an increase incoupling that was rapidly reversed by bicuculline.(ABSTRACT TRUNCATED AT250 WORDS)

Schlagwörter Aminobutyric Acidspharmacology; Animals; Benzazepinespharmacology;Bicucullinepharmacology; Darkness; Dopaminemetabolism; Dopamine Antagonists;Fluphenazinepharmacology; Necturus; Photic Stimulation;Retinacytologymetabolism; Visual Fieldsdrug effects

Falkowska, Z. (1976): [Harmful effects of flickering light]. In: Klinika oczna, Jg. 46, H. 7, S. 823–825.Schlagwörter Adult; Child; Epilepsyetiology; Female; Humans; Male; Photic Stimulationadverse

effectsinstrumentation

Falsini, B.; Fadda, A.; Iarossi, G.; Piccardi, M.; Canu, D.; Minnella, A. et al. (2000): Retinal sensitivity to flickermodulation: reduced by early age-related maculopathy. In: Investigative ophthalmology & visual science, Jg. 41,H. 6, S. 1498–1506.Abstract PURPOSE: To evaluate retinal, cone-mediated flicker sensitivity (CFS) in age-

related maculopathy (ARM) by quantifying response gain and threshold of the focalelectroretinogram (FERG) to flicker modulation. METHODS: Nineteen patients withARM (visual acuity > or =20/30) and 11 age-matched control subjects wereexamined. Twelve patients had less than 20 soft drusen in the macular region andno hyper-/hypopigmentation (early lesion), whereas seven had more than 20 softdrusen and/or focal hyper-/hypopigmentation (advanced lesion). Macular (18degree ) FERGs were elicited by a sinusoidally flickering (41 Hz) uniform field (on alight-adapting background) whose modulation depth was varied between 16.5% and94%. Amplitude and phase of the response's fundamental harmonic weremeasured. RESULTS: In both control subjects and patients with ARM, log FERGamplitude increased with log stimulus modulation depth with a straight line (powerlaw) relation. However, the slope (or gain) of the function was, on average, steeperin control subjects than in patients with either early or advanced lesions. MeanFERG threshold, estimated from the value of the log modulation depth that yieldeda criterion response, did not differ between control subjects and patients with earlylesions but was increased (0.35 log units) compared with control subjects in thosewith advanced lesions. In both patient groups, but not in control subjects, meanFERG phase tended to delay with decreasing stimulus modulation depth.CONCLUSIONS: Retinal CFS losses can be detected in ARM by evaluating theFERG as a function of flicker modulation depth. Reduced response gain and phasedelays, with normal thresholds, are associated with early lesions. Increasedresponse thresholds, in addition to gain and phase abnormalities, may reflect moreadvanced lesions. Evaluating CFS by FERG may directly document different stagesof macular dysfunction in ARM.

Schlagwörter Aged; Aged, 80 and over; Color Vision Defectsphysiopathology;Electroretinographymethods; Female; Flicker Fusion; Humans; MacularDegenerationphysiopathology; Male; Middle Aged; Retinal Cone PhotoreceptorCellsphysiopathology; Visual Acuity

iLib08 - CitaviiLib08 - CitaviiLib08 - CitaviiLib08 - CitaviFriedman, Deborah I.; Dye, Timothy de ver (2009): Migraine and the environment. In: Headache, Jg. 49, H. 6, S.941–952. Online verfügbar unter doi:10.1111/j.1526-4610.2009.01443.x.Abstract Migraineurs often describe environmental triggers of their headaches, such as

barometric pressure change, bright sunlight, flickering lights, air quality, and odors.Environmental aspects of indoor space and workplaces are also implicated inmigraine experience. Comprehensive migraine treatment programs emphasizeawareness and avoidance of trigger factors as part of the therapeutic regimen. Asmigraine has a substantial economic impact, remediation of correctableenvironmental triggers may benefit employee attendance and productivity amongmigraineurs. Few controlled studies in the literature, however, confirmenvironmental influences on migraine and headaches. Although some arecontroversial, migraineurs worldwide consistently report similar environmentaltriggers. This article addresses commonly mentioned environmental triggers with adiscussion of their pathophysiology and proposed preventive measures.OBJECTIVE: To examine the epidemiological evidence for commonly-mentionedenvironmental migraine triggers, discuss their possible role in the pathophysiologyof migraine and propose preventive measures to avoid or minimize exposure.BACKGROUND: Migraineurs often describe environmental triggers of theirheadaches, such as barometric pressure change, bright sunlight, flickering lights,air quality and odors. Environmental aspects of indoor space and workplaces arealso implicated in the migraine experience. As migraine has a substantial economicimpact, remediation of correctable environmental triggers may improve attendanceand productivity among migraineurs in the workplace. METHODS: We reviewed theliterature addressing indoor and outdoor environmental factors which are commonlyimplicated as migraine triggers. RESULTS: Although some factors arecontroversial, migraineurs worldwide consistently report similar environmentaltriggers. However, few studies confirm environmental influences on migraine andheadaches. Research to date indicates that migraineurs have lower thresholds forlight-induced discomfort, sine grating distortion and illusions, noise tolerance andolfactory sensitivity compared to the general population. CONCLUSION: There areconflicting studies supporting the validity of patient-reported environmental migrainetriggers. Prospective studies are needed to determine the extent that externalstimuli influence the migraine process. Decreased thresholds for light, noise,olfactory and visual stimuli in migraineurs may be minimized by modifying the work,home and classroom settings.

Grădină, C.; Chihaia, V.; Constantinidis, A.; Cristian, K.: [Electroencephalographic studies of personsexperimentally exposed to flickering and non-flickering incandescent and fluorescent lighting]. In: Fiziologianormală şi patologică, Jg. 12, H. 4, S. 317–325.Schlagwörter Cerebral Cortexphysiology; Electroencephalography; Fluorescence; Humans;

Lighting

GRANDA, A. M. (1961): Electrical responses of the human eye to colored flickering light. In: Journal of theOptical Society of America, Jg. 51, S. 648–654.Schlagwörter Color Perceptionphysiology; Ocular Physiological Phenomena

Guggenheim, P.; Scollo-Lavizzari, G.; Hess, R. (1968): [Diagnostic singificance of increased brain electricreaction to flickering light]. In: Fortschritte der Neurologie, Psychiatrie, und ihrer Grenzgebiete, Jg. 36, H. 6, S.342–372.Schlagwörter Adolescent; Adult; Child; Electroencephalography; Epilepsydiagnosis; Female;

Humans; Light; Male; Methods; Migraine Disordersdiagnosis; Nervous SystemDiseasesdiagnosis; Photosensitivity Disorders; Seizuresdiagnosis

Guignard, C.; van Toi, V.; Burckhardt, C. W.; Schelling, J. L. (1983): Effect of digoxin on the sensitivity toflickering light. In: British journal of clinical pharmacology, Jg. 15, H. 2, S. 189–196.Abstract 1 The sensitivity to flickering light at various light frequencies (DeLange curve) was

iLib08 - CitaviiLib08 - CitaviiLib08 - CitaviiLib08 - Citavidetermined in 20 controls and 45 patients receiving maintenance doses of digoxin.2 Flicker thresholds (mean percentage of maximal light modulation +/- s.d.; F 30Hz) were 7.6 +/- 1.7 in controls and 9.4 +/- 1.7 in patients with optimal plasmadigoxin levels (0.5-1.9 ng/ml), but they rose to 15.5 +/- 1.9 at subtoxic levels (2.0-3.0 ng/ml), and to 21.8 +/- 2.6 at toxic levels (above 3.0 ng/ml). 3 Flicker sensitivitywas inversely correlated with plasma digoxin levels and returned to baseline valueswhen the administration of digoxin was interrupted. 4 The DeLange curve seems tobe a valuable tool to measure the toxic effects of digitalis on the visual system.

Schlagwörter Digoxinbloodpoisoning; Female; Flicker Fusiondrug effects; Humans;Lightdiagnostic use; Male

Haamedi, Sakineh N.; Djamgoz, Mustafa B. A. (2002): Dopamine and nitric oxide control both flickering andsteady-light-induced cone contraction and horizontal cell spinule formation in the teleost (carp) retina: serialinteraction of dopamine and nitric oxide. In: The Journal of comparative neurology, Jg. 449, H. 2, S. 120–128.Online verfügbar unter doi:10.1002/cne.10278.Abstract Adaptation to ambient light, which is an important characteristic of the vertebrate

visual system, involves cellular and subcellular (synaptic) plasticity of the retina.The present study investigated dopamine (DA) and nitric oxide (NO) as possibleneurochemical modulators controlling cone photomechanical movements (PMMs)and horizontal cell (HC) spinules in relation to steady and flickering light adaptationin the carp retina. Haloperidol (HAL; a nonspecific DA receptor blocker) or cPTIO (aNO scavenger) largely inhibited the cone PMMs and HC spinule formation inducedby either steady or flickering light. These results suggested that both DA and NOcould be involved in the light-adaptation changes induced by either pattern of inputand that DA and NO effects may not be completely independent. The possibility thatNO and DA interact serially was evaluated pharmacologically by cross-antagonistapplication (i.e., DA + cPTIO or NO + HAL). When a NO donor was coapplied withHAL to dark-adapted eyecups, normal light-adaptive cone PMMs and HC spinulesoccurred. In contrast, when DA was applied in the presence of cPTIO, the dark-adapted state persisted. It was concluded 1) that DA and NO are both light-adaptiveneurochemicals, released in the retina during either steady or flickering light; 2) thatthe effects of DA and NO on light-adaptive cone PMMs and HC spinules do notoccur in parallel; and 3) that NO and DA act mainly in series, specifically as follows:Light --> DA --> NO --> Cone PMMs + HC spinules.

Schlagwörter Adaptation, Ocularphysiology; Animals; Carpsmetabolism;Dopaminemetabolismphysiologysecretion; Flicker Fusionphysiology; Light; NitricOxidemetabolismphysiologysecretion; Photic Stimulationmethods;Retinametabolismphysiologysecretion; Retinal Cone PhotoreceptorCellsmetabolismphysiologysecretion

Hasenöhrl, R.; Berger, H. (1970): [Influence of intensive dazzling stimuli on the electroretinogram ofmonochromatic flickering light in man]. In: Acta biologica et medica Germanica, Jg. 25, H. 5, S. 847–854.Schlagwörter Accommodation, Ocular; Adaptation, Ocular; Adult; Amplifiers, Electronic;

Electrophysiology; Electroretinography; Humans; Light; Male; PhotosensitivityDisorders; Retinaphysiology

HAUSLER, H. P.; Siedek, H. (1951): [Studies on the effect of minimal work and flickering light on circulation andgaseous metabolism.]. In: Cardiologia, Jg. 18, H. 4, S. 233–243.Schlagwörter Blood Circulation; Light; Work

Herrmann, C. S. (2001): Human EEG responses to 1-100 Hz flicker: resonance phenomena in visual cortex andtheir potential correlation to cognitive phenomena. In: Experimental brain research. ExperimentelleHirnforschung. Expérimentation cérébrale, Jg. 137, H. 3-4, S. 346–353.Abstract The individual properties of visual objects, like form or color, are represented in

different areas in our visual cortex. In order to perceive one coherent object, itsfeatures have to be bound together. This was found to be achieved in cat and

iLib08 - CitaviiLib08 - CitaviiLib08 - CitaviiLib08 - Citavimonkey brains by temporal correlation of the firing rates of neurons which code thesame object. This firing rate is predominantly observed in the gamma frequencyrange (approx. 30-80 Hz, mainly around 40 Hz). In addition, it has been shown inhumans that stimuli which flicker at gamma frequencies are processed faster by ourbrains than when they flicker at different frequencies. These effects could be due toneural oscillators, which preferably oscillate at certain frequencies, so-calledresonance frequencies. It is also known that neurons in visual cortex respond toflickering stimuli at the frequency of the flickering light. If neural oscillators exist withresonance frequencies, they should respond more strongly to stimulation with theirresonance frequency. We performed an experiment, where ten human subjectswere presented flickering light at frequencies from 1 to 100 Hz in 1-Hz steps. Theevent-related potentials exhibited steady-state oscillations at all frequencies up to atleast 90 Hz. Interestingly, the steady-state potentials exhibited clear resonancephenomena around 10, 20, 40 and 80 Hz. This could be a potential neural basis forgamma oscillations in binding experiments. The pattern of results resembles that ofmultiunit activity and local field potentials in cat visual cortex.

Schlagwörter Adult; Brain Mapping; Cognitionphysiology; Electroencephalography; EvokedPotentials; Female; Humans; Male; Photic Stimulation; Visual Cortexphysiology

Hess, R. F.; Harding, G. F.; Drasdo, N. (1974): Seizures induced by flickering light. In: American journal ofoptometry and physiological optics, Jg. 51, H. 8, S. 517–529.Schlagwörter Action Potentials; Age Factors; Anticonvulsantstherapeutic use; Behavior Therapy;

Brainphysiopathology; Contact Lenses; Electroencephalography; Epilepsydrugtherapyetiologyphysiopathologytherapy; Eyeglasses; Female; Humans;Lightadverse effects; Male; Photic Stimulation; Sex Factors; Television; TimeFactors

HOFMANN-CREDNER, D. (1953): [Effect of flickering light on water diuresis in man.]. In: Helvetica medica acta,Jg. 20, H. 1, S. 1–19.Schlagwörter Diuresis

Horn, F. K.; Link, B.; Dehne, K.; Lämmer, R.; Jünemann, A. G. (2006): [Flicker provocation with LED full-fieldstimulation in normals and glaucoma patients]. In: Der Ophthalmologe : Zeitschrift der DeutschenOphthalmologischen Gesellschaft, Jg. 103, H. 10, S. 866–872. Online verfügbar unter doi:10.1007/s00347-006-1389-5.Abstract BACKGROUND: Flicker light is an easy method to test sensory function after

stress. The aim of this study was to determine the influence of flicker stress ontemporal contrast sensitivity in healthy controls and patients with glaucomatousalteration of the optic disk. METHODS: A commercially available full-field stimulator(Retiport, Roland Consult) equipped with white LEDs was modified to performpsychophysical tests. The patients underwent measurements of the recovery timeinterval from cessation of flicker stress until recognition of a pregiven flicker contrastafter photo stress. In addition, we studied contrast sensitivity with a continuousflickering target and with a flicker burst protocol avoiding adaptation to prevailingflicker. All tests were performed at a constant retinal illumination and at a frequencyof 37 Hz for provocation as well as for contrast sensitivity tests. SUBJECTS: Normalhealthy controls (40), "preperimetric" (62), and "perimetric" (52) open-angleglaucoma patients were studied. Exclusion criteria were age lower than 31 years,visual acuity under 0.6, and perimetric mean defect more than 9.5 dB. RESULTS:Recovery time after flicker stress was significantly longer in patients than in normalsand longer in perimetric than in preperimetric patients. Analysis in perimetricpatients revealed a larger area under ROC for the provocation test (0.95) than incontrast sensitivity tests (continuous flicker method: 0.90, flicker burst mode: 0.84).CONCLUSION: High-power LEDs which are installed in modern full-field devicescan be used as a helpful tool to study psychophysical properties. In the presentstudy it could be shown that threshold, adaptation, and recovery of temporal

iLib08 - CitaviiLib08 - CitaviiLib08 - CitaviiLib08 - Citavitransfer characteristics are impaired in many patients with glaucoma.

Schlagwörter Contrast Sensitivity; Female; Flicker Fusion; Glaucomadiagnosis; Humans;Lightinginstrumentationmethods; Male; Middle Aged;Perimetryinstrumentationmethods; Photic Stimulationinstrumentationmethods;Reference Values; Reproducibility of Results; Semiconductors; Sensitivity andSpecificity

Isokawa-Akesson, M.; Komisaruk, B. R. (1985): Tuning the power spectrum of physiological finger tremorfrequency with flickering light. In: Journal of neuroscience research, Jg. 14, H. 3, S. 373–380. Online verfügbarunter doi:10.1002/jnr.490140309.Abstract Fast Fourier Transform analyses were performed on finger tremor movements at

0.2-Hz intervals from 0.4 to 40 Hz in 10 human subjects, under a flickering lightcondition of 4-15 Hz and an unstimulated control condition. Under the controlcondition, the power spectrum showed an essentially normal curve distribution,except for an early frequency component in the histogram. In contrast, when theflickering light stimulus was presented, the power of specific frequency componentsat 8-11 Hz was strongly enhanced. This effect was induced exclusively at afrequency of 8, 9, or 11 Hz of flickering light, and this flickering frequency producingthe enhancement effect differed from subject to subject. There existed a significantcorrelation between the frequencies of flicker and tremor at the tuned frequency.These findings demonstrate that a specific frequency of flickering light can intensifya specific frequency of physiological finger tremor, and that different individualsexhibit different optimal "tuning" frequencies.

Schlagwörter Adult; Electroencephalography; Female; Fingersphysiology; Fourier Analysis;Humans; Male; Movement; Photic Stimulation

Jacome, D. E.; Risko, M. (1986): Lightning artifact in the EEG. In: Clinical EEG (electroencephalography), Jg.17, H. 2, S. 105–109.Abstract Lightning is highly prevalent in South Florida. The artifact caused by lightning in

EEG recordings is of variable duration and seen as abrupt deflection of pens,sometimes followed by sustained pen drift and slow recovery mimicking amplifieroverload as caused by rapid unplugging and plugging of the equipment power cablefrom the wall outlet. Since this artifact was associated to hospital light flickering andwas recorded independent of machine location and orientation, we believe it issecondary to extreme brief Mains voltage fluctuations, probably due to horizontallightning electric field effects rather than radio or electromagnetic interferencegenerated by lightning.

Schlagwörter Electroencephalography; Florida; Humans; Lightning

Kanai, Ryota; Chaieb, Leila; Antal, Andrea; Walsh, Vincent; Paulus, Walter (2008): Frequency-dependentelectrical stimulation of the visual cortex. In: Current biology : CB, Jg. 18, H. 23, S. 1839–1843. Online verfügbarunter doi:10.1016/j.cub.2008.10.027.Abstract Noninvasive cortical stimulation techniques, such as transcranial magnetic

stimulation (TMS) and transcranial direct current stimulation (tDCS), have proved tobe powerful tools for establishing causal relationships between brain regions andtheir functions. In the present study, we demonstrate that a new technique calledtranscranial alternating current stimulation (tACS) can interact with ongoingrhythmic activities in the visual cortex in a frequency-specific fashion and inducevisual experiences (phosphenes). We delivered an oscillatory current over theoccipital cortex with tACS. In order to observe interactions with ongoing corticalrhythms, we compared the effects of delivering tACS under conditions of light("Light" condition) or darkness ("Dark" condition). Stimulation over the occipitalcortex induced perception of continuously flickering light most effectively when thebeta frequency range was applied in an illuminated room, whereas the mosteffective stimulation frequency shifted to the alpha frequency range during testing indarkness. Stimulation with theta or gamma frequencies did not produce any visual

iLib08 - CitaviiLib08 - CitaviiLib08 - CitaviiLib08 - Citaviphenomena. The shift of the effective stimulation frequency indicates that thefrequency dependency is caused by interactions with ongoing oscillatory activity inthe stimulated cortex. Our results suggest that tACS can be used as a noninvasivetool for establishing a causal link between rhythmic cortical activities and theirfunctions.

Schlagwörter Darkness; Electric Stimulationmethods; Female; Humans; Light; Male;Phosphenesphysiology; Visual Cortexphysiology; Visual Perceptionphysiology

Kelly, D. H. (1975): Luminous and chromatic flickering patterns have opposite effects. In: Science (New York,N.Y.), Jg. 188, H. 4186, S. 371–372.Abstract When stimulated in phase by a sinusoidally flickering, uniform field, the red and

green cone systems tend to inhibit each other. This inhibition is minimized by (i)counterphase (luminance) patterns or (ii) red/green (chromaticity) flicker. However,when (i) and (ii) are combined, the usual flickering-pattern effect is reversed:instead of enhancing chromatic flicker, counterphase patterns tend to suppress it.

Schlagwörter Color Perception; Discrimination (Psychology); Flicker Fusion; Humans; InformationTheory; Light; Models, Neurological; Pattern Recognition, Visual; PhoticStimulation; Photoreceptor Cellsphysiology; Visual Fields

Kim, R. Y.; Retsas, S.; Fitzke, F. W.; Arden, G. B.; Bird, A. C. (1994): Cutaneous melanoma-associatedretinopathy. In: Ophthalmology, Jg. 101, H. 11, S. 1837–1843.Abstract PURPOSE: To define further the syndrome of cutaneous melanoma-associated

retinopathy, of which only five affected patients have been reported previously.METHODS: Three men with melanoma-associated retinopathy were examined andstudied electrophysiologically. Two were studied in detail psychophysically.RESULTS: Visual symptoms consisted of flickering black and white spots,shimmering patches of colors, and night blindness. The onset was acute andnonprogressive. Reduced amplitudes were observed in the flashelectroretinographic b-wave and the pattern electroretinogram. Color vision,contrast sensitivity, and light- and dark-adapted perimetric sensitivities wereabnormal. In one patient, the rate of dark adaptation was normal with elevated finalcone and rod thresholds. CONCLUSIONS: Melanoma-associated retinopathy is aparaneoplastic syndrome distinct from cancer-associated retinopathy with adifferent visual prognosis. It may preferentially affect men.

Schlagwörter Aged; Color Vision Defectsetiology; Dark Adaptation; Electroretinography; Humans;Male; Melanomacomplications; Middle Aged; Paraneoplastic Syndromes;Prognosis; Retinal Diseasesdiagnosisetiology; Skin Neoplasmscomplications;Vision Disordersdiagnosisetiology; Vision Tests; Visual Acuity

Kiryu, J.; Asrani, S.; Shahidi, M.; Mori, M.; Zeimer, R. (1995): Local response of the primate retinalmicrocirculation to increased metabolic demand induced by flicker. In: Investigative ophthalmology & visualscience, Jg. 36, H. 7, S. 1240–1246.Abstract PURPOSE. To study the response of the macular circulation to a local increase in

metabolic demand created by a flickering source of illumination. METHODS. Laser-targeted angiography (release of a fluorescent dye from heat-sensitive liposomesusing a laser pulse) was used to study, in subhuman primates, changes inhemodynamic parameters of the retinal circulation that were induced by a flickeringsource of illumination. Changes in the macular macrocirculation were comparedwith those in the macular microcirculation and were evaluated at various distancesfrom the foveola. RESULTS. In response to monochromatic light flicker, the bloodflow in retinal arteries increased by 30%. The response of the microcirculation wasnot homogeneous. It showed a maximum increase in the mid-perifoveal regionwhere there is an increase in ganglion cells and nerve fibers. Interestingly, themaximum change in the index representing capillary blood flow exceeded the bloodflow change in the artery (P < 0.08). CONCLUSIONS. A stimulus expected to causeincreased metabolic demand results in a regulatory response by the retinal

iLib08 - CitaviiLib08 - CitaviiLib08 - CitaviiLib08 - Citavimicrocirculation. This response shows spatial variations that correspond with knownvariations in retinal anatomy. The authors propose that a redistribution of blood canoccur between the capillary layers to fulfill high metabolic demands by neuronaltissue remote from the choroid.

Schlagwörter Animals; Arteriolesphysiology; Blood Flow Velocityphysiology; FluoresceinAngiography; Fundus Oculi; Hemodynamicsphysiology; Image Processing,Computer-Assisted; Light; Macula Luteablood supply; Microcirculation; Papio;Retinametabolismradiation effects; Retinal Vesselsphysiologyradiation effects

Kolbinger, W.; Weiler, R.: Modulation of endogenous dopamine release in the turtle retina: effects of light,calcium, and neurotransmitters. In: Visual neuroscience, Jg. 10, H. 6, S. 1035–1041.Abstract In the turtle retina, dopamine has been observed in a small population of amacrine

cells. Whereas the effect of dopamine has been intensively studied, knowledgeabout the release of this transmitter and the neuronal control of its release are stillpoorly understood. We therefore decided to study the release of endogenousdopamine. Isolated retinas were superfused with Ringer's solutions and stimulatedwith increased potassium, light, or drugs which interfere with neurotransmittersystems. Dopamine was analyzed by using aluminum-oxide extraction and high-pressure liquid chromatography (HPLC) with electrochemical detection. Increasedpotassium (25 mM) caused a five-fold increase in the basal release. When calciumwas replaced by cobalt, no increase was induced by 25 mM potassium. Flickeringlight increased the basal release of endogenous dopamine by a factor of three. Theeffect of flickering light was greater in the presence of additional steady backgroundillumination. Kainate (10 microM), an agonist for excitatory amino acids, doubled thebasal dopamine release. Bicuculline (10 microM), a gamma-amino butyric acid(GABA) antagonist, increased the release to about six times the basal level.Naloxone (10 microM), an opiate antagonist, increased the release to eight timesthe basal level. These findings suggest that dopamine is released from amacrinecells in the turtle retina in a calcium-dependent manner, which is most likely avesicular release. Dopamine release is induced by flickering light vs. darkness andvs. steady background illumination. A moderate background illumination alone doesnot significantly increase basal dopamine release.(ABSTRACT TRUNCATED AT250 WORDS)

Schlagwörter Animals; Calciumpharmacology; Chromatography, High Pressure Liquid;Dopaminebiosynthesis; Light; Neurotransmitter Agentspharmacology;Potassiumpharmacology; Retinadrug effectsmetabolism; Turtles

Korol, S.; Chanson, J. F.; Meyer, J. J. (1976): [The use of flickering light in the functional study of the macula].In: Bulletins et mémoires de la Société française d'ophtalmologie, Jg. 88, S. 30–39.Schlagwörter Adolescent; Adult; Child; Electroretinography; Female; Flicker Fusion; Humans;

Macular Degenerationdiagnosis; Male; Middle Aged; Retinal Degenerationdiagnosis

Kowacs, P. A.; Piovesan, E. J.; Werneck, L. C.; Fameli, H.; Pereira da Silva, H. (2004): Headache related to aspecific screen flickering frequency band. In: Cephalalgia : an international journal of headache, Jg. 24, H. 5, S.408–410. Online verfügbar unter doi:10.1111/j.1468-2982.2004.00686.x.Abstract The case of a 25-year-old white male, who had migrainous headaches each time he

sat in front of his personal computer screen, is described. Changing the screenfrequency from 60 to 75 Hz through a Windows command could abolish theheadaches. In several surveys, computer screens have been reported to be amigraine trigger. We hypothesize that this environmental trigger may be related tothe abnormal flicker fusion thresholds that have been described in migraineurs. Itmay be that modifying the frequencies of light sources, such as computer screens,could become a non-pharmacological approach to prevent migraine attacks.

Schlagwörter Adult; Computer Terminals; Headacheetiology; Humans; Male; PhoticStimulationadverse effects

iLib08 - CitaviiLib08 - CitaviiLib08 - CitaviiLib08 - CitaviLalitha, R.; Suthanthirarajan, N.; Namasivayam, A.: Effect of flickering light stress on certain biochemicalparameters in rats. In: Indian journal of physiology and pharmacology, Jg. 32, H. 3, S. 182–186.Abstract The acute effects of flickering light of 80 Lux intensity for thirty minutes duration, on

plasma corticosterone, total serum cholesterol, serum triglycerides, serum glutamicpyruvic transaminase (SGPT) and serum glutamic oxaloacetic transaminase(SGOT) levels were studied in albino rats. Statistically significant increase wasobserved in the corticosterone, cholesterol, SGOT and SGPT, while a markedreduction was seen in the serum triglyceride level, indicating that the flickering lightis a potent stressor to these animals causing alterations in the biochemicalparameters studied.

Schlagwörter Alanine Transaminaseblood; Animals; Aspartate Aminotransferasesblood;Cholesterolblood; Corticosteroneblood; Female; Lightadverse effects; Male; Rats;Rats, Inbred Strains; Stress, Physiologicalbloodetiology; Triglyceridesblood

Maddocks, S. A.; Goldsmith, A. R.; Cuthill, I. C. (2001): The influence of flicker rate on plasma corticosteronelevels of European starlings, Sturnus vulgaris. In: General and comparative endocrinology, Jg. 124, H. 3, S.315–320. Online verfügbar unter doi:10.1006/gcen.2001.7718.Abstract Recent reviews have highlighted the differences between human and avian vision

with regard to temporal resolution and the potential problems it may cause for avianwelfare and video playback experiments. Birds tend to have much higher criticalfusion frequencies than do humans (>100 Hz vs 50-60 Hz in humans), whichmeans that they perceive light as flickering up to and over 100 Hz. This is higherthan most television monitors (which have refresh rates of 50 or 60 Hz) and normalfluorescent lighting (100 or 120 Hz), and because humans find flickering lightaversive, it has been suggested that birds will as well. If this were the case, thenthere would be welfare implications of maintaining them under such lighting andalso a potential effect on their behavioral responses in video playback experiments.However, there is some behavioral evidence that indicates that birds do not appearto find flicker aversive and may even prefer flickering lighting. The authors aimed todetermine whether a passerine, the European starling, found flicker aversive bymeasuring the corticosterone stress response in birds maintained under high- orlow-frequency fluorescent lighting (35-40 kHz vs 100 Hz) for 1 or 24 h. The resultssuggest that low-frequency lighting is potentially more stressful because, wheredifferences exist, birds in the low-frequency treatment always showed higher basalcorticosterone. However, the evidence is not consistent because in half of theblocks, there were no significant treatment effects and, where there were, the timecourse of the effects was variable.

Schlagwörter Animals; Corticosteroneblood; Flicker Fusion; Songbirdsblood

Mäkelä, P.; Rovamo, J.; Whitaker, D. (1994): Effects of luminance and external temporal noise on flickersensitivity as a function of stimulus size at various eccentricities. In: Vision research, Jg. 34, H. 15, S.1981–1991.Abstract We studied how the dependence of flicker sensitivity on stimulus size was affected

by the eccentricity of the stimulus at high luminance, at low luminance (with quantalnoise), and at high luminance with the addition of pure white temporal noise. Flickersensitivity was measured as a function of stimulus size for temporal frequencies of1-30 Hz with uniform sinusoidally flickering spots. Sensitivity first increased withincreasing stimulus size but then the increase saturated. At high luminance thesaturation took place at larger stimulus sizes with increasing eccentricity. Withoutexternally added temporal noise the maximum sensitivity was higher at the foveathan in the periphery at temporal frequencies of 1-10 Hz, but at 30 Hz this situationreversed. Therefore only the ascending parts of the spatial integration curves fromvarious eccentricities could be superimposed by size scaling. E2, the eccentricity atwhich the spatial scale doubles, was found to be 2.2-2.7 deg for 1-10 Hz but 4.4deg for 30 Hz. When enough temporal noise was added, performance at allstimulus sizes studied could be made independent of eccentricity by spatial scaling,

iLib08 - CitaviiLib08 - CitaviiLib08 - CitaviiLib08 - Citavisince noise reduced maximum sensitivities to a constant level at all eccentricities.E2 was found to be 4.1 deg for 3 Hz and 7.2 deg for 30 Hz. When light level wasreduced by 3 log10 units, foveal and peripheral flicker sensitivity functions almostsuperimposed at all stimulus sizes studied. Hence, at 1 and 3 Hz E2 was very large,about 70 and 22 deg, respectively. At 10 and 30 Hz no size scaling was neededand E2 was therefore infinite.

Schlagwörter Adult; Flicker Fusionphysiology; Fovea Centralisphysiology; Humans; Light;Photometry; Size Perceptionphysiology; Time Factors; Visual Fields

Mandecka, Aleksandra; Dawczynski, Jens; Blum, Marcus; Müller, Nicolle; Kloos, Christoph; Wolf, Gunter et al.(2007): Influence of flickering light on the retinal vessels in diabetic patients. In: Diabetes care, Jg. 30, H. 12, S.3048–3052. Online verfügbar unter doi:10.2337/dc07-0927.Abstract OBJECTIVE: Stimulation of the retina with flickering light increases retinal vessel

diameters in humans. Nitric oxide is a mediator of the retinal vasodilation to flicker.The reduction of vasodilation is considered an endothelial dysfunction. Weinvestigated the response of retinal vessels to flickering light in diabetic patients indifferent stages of diabetic retinopathy. RESEARCH DESIGN AND METHODS: Westudied 53 healthy volunteers, 68 type 1 diabetic patients, and 172 type 2 diabeticpatients. The diameter of retinal vessels was measured continuously online with theDynamic Vessel Analyzer (DVA). Diabetic retinopathy was classified using EarlyTreatment Diabetic Retinopathy Study criteria. Changes in vasodilation areexpressed as percent change over baseline values. RESULTS: After adjustmentsfor age, sex, and antihypertensive treatment, the response of retinal arterioles todiffuse luminance flicker was significantly diminished in patients with type 1diabetes compared with healthy volunteers. The vasodilation of retinal arteriolesand venules decreased continuously with increasing stages of diabetic retinopathy.The retinal arterial diameter change was 3.6 +/- 2.1% in the control group, 2.6 +/-2.5% in the no diabetic retinopathy group, 2.0 +/- 2.7% in the mild nonproliferativediabetic retinopathy (NPDR) group, 1.6 +/- 2.2% in the moderate NPDR group, 1.8+/- 1.9% in severe NPDR group, and 0.8 +/- 1.6% in proliferative diabeticretinopathy group. CONCLUSIONS: Flicker responses of retinal vessels areabnormally reduced in diabetic patients. This decreased response deteriorated withincreasing stages of retinopathy. The response was already reduced before clinicalappearance of retinopathy. The noninvasive testing of retinal autoregulation withDVA might prove to be of value in early detection of diabetic vessel pathologicalchanges.

Schlagwörter Adult; Aged; Arteriolesphysiopathologyradiation effects; Diabetes Mellitus, Type1physiopathology; Diabetic Retinopathyphysiopathology; Female; FlickerFusionphysiology; Humans; Light; Male; Middle Aged; Patient Selection; PhoticStimulation; Reaction Time; Reference Values; Retinal Vesselsphysiopathology;Vasodilationphysiology; Vision Disordersepidemiologyphysiopathology

Mandecka, Aleksandra; Dawczynski, Jens; Vilser, Walthard; Blum, Marcus; Müller, Nicolle; Kloos, Christoph etal. (2009): Abnormal retinal autoregulation is detected by provoked stimulation with flicker light in well-controlledpatients with type 1 diabetes without retinopathy. In: Diabetes research and clinical practice. Online verfügbarunter doi:10.1016/j.diabres.2009.06.017.Abstract AIMS: Investigation of retinal vasodilation under flickering light is considered a

dynamic analysis in contrast to the static analysis of retinal vessel equivalents(mean retinal vessel diameter). We investigated whether dynamic analysis apartfrom the static one in type 1 diabetic patients without diabetic retinopathy with well-controlled diabetes could lead to additional information regarding retinalautoregulation. METHODS: 18 normotensive type 1 diabetic patients withoutretinopathy and 19 healthy subjects were included. Diameter of retinal vessels wasmeasured with Dynamic Vessel Analyzer. Changes in vasodilation are expressedas percent change over baseline values. RESULTS: HbA(1c) was 7.5+/-1.0% indiabetic patients. In arteries, the response to flicker was diminished in diabetic

iLib08 - CitaviiLib08 - CitaviiLib08 - CitaviiLib08 - Citavipatients compared to healthy volunteers (p<0.023). In patients flicker stimulationincreased arterial diameter by +2.7% in contrast to +4.4% in controls. Venousvessel diameter increased by +3.1% in diabetic individuals and by +5.3% in thecontrol group (p<0.002). There were no differences in static analysis between bothgroups. CONCLUSIONS: Diabetic patients without retinopathy with relatively goodglycemic control show reduced retinal vasodilation after flicker indicatingdysfunction in retinal autoregulation. The use of provocation test in conjunction withstatic analysis could lead to additional information regarding abnormal retinalautoregulation.

Mayr, N.; Wimberger, D.; Pichler, H.; Mamoli, B.; Zeitlhofer, J.; Spiel, G. (1987): Influence of television onphotosensitive epileptics. In: European neurology, Jg. 27, H. 4, S. 201–208.Abstract We examined 32 epileptics (20 female; 12 male; aged 6-73 years) who had

displayed photoconvulsive reactions to flickering light in the EEG; they wereexamined with regard to their risks of getting epileptic seizures upon watchingtelevision (TV) under certain conditions. On a colour TV set each patient was showna 3-min videofilm with slow- and fast-moving parts under 16 different conditions.The conditions had the following variables: (1) colour - monochrome; (2) dark room- light room, and (3) four different distances from the screen. In addition, eachpatient was subjected for 3 min to manipulated image interferences, including thevertical rolling of the picture. The results of this TV stimulation were alwaysnegative, i.e. in no patient did TV provoke a reproducible paroxysmal discharge inthe EEG, nor was there any epileptic seizure. Our findings are discussed inconnection with the corresponding literature.

Schlagwörter Adolescent; Adult; Aged; Child; Electroencephalography; Epilepsies, Partialetiology;Epilepsyetiology; Epilepsy, Absenceetiology; Evoked Potentials, Visual; Female;Humans; Male; Middle Aged; Photic Stimulation; Television

Michelson, George; Patzelt, Alexander; Harazny, Joana (2002): Flickering light increases retinal blood flow. In:Retina (Philadelphia, Pa.), Jg. 22, H. 3, S. 336–343.Abstract PURPOSE: To examine the retinal blood flow in normal eyes before and during

retinal stimulation by flickering light. DESIGN: A prospective cross-sectional study.PARTICIPANTS AND TESTING: Twenty-seven eyes of 27 normal subjects with amean age +/- SD of 38 +/- 15 years (study I) and 21 eyes of 21 normal subjects witha mean age +/- SD of 46 +/- 17 years (study II) were examined with respect tocapillary retinal blood flow and central retinal artery and central retinal vein bloodflow velocities during flickering light stimulation. A luminance flicker light with afrequency of 8 Hz increased the neuronal activity of retinal ganglion cells. In study I,the retinal capillary blood flow was measured before and during flickering byscanning laser Doppler flowmetry (670 nm, Heidelberg Retina Flowmeter). In studyII, the blood flow velocities in the central retinal artery and central retinal vein wereexamined by pulsed Doppler sonography. MAIN OUTCOME MEASURES: Changein blood flow velocities in the central retinal artery and vein and in retinal capillaryblood flow after full-field flicker stimulation. RESULTS: In study I, measurements ofblood flow during retinal flicker stimulation showed a significant increase in themean value of blood flow +/- SD from 317 +/- 72 arbitrary units to 416 +/- 103arbitrary units. The change was on average 46 +/- 19%. In study II, the systolic andend-diastolic blood flow velocities in the central retinal artery increased significantly(P < 0.0001): systolic, 9 cm/s to 15 cm/s (+62%); end-diastolic, 2.7 cm/s to 5.3 cm/s(+96%). In the central retinal vein, the systolic and end-diastolic blood flowvelocities increased significantly (P < 0.0001): systolic, 4.3 cm/s to 6.7 cm/s (+56%);end-diastolic, 1.8 cm/s to 3.6 cm/s (+100%). The authors found no significantchange in blood pressure and heartbeat frequency. CONCLUSIONS: Visualstimulation of the retina by flickering light strongly increased the juxtapapillaryretinal capillary blood flow and central retinal artery blood flow velocity in normaleyes.

iLib08 - CitaviiLib08 - CitaviiLib08 - CitaviiLib08 - CitaviSchlagwörter Adult; Blood Flow Velocityradiation effects; Blood Pressure; Capillaries; Cross-

Sectional Studies; Heart Rate; Humans; Intraocular Pressure; Laser-DopplerFlowmetry; Light; Middle Aged; Photic Stimulation; Prospective Studies;Retinaradiation effects; Retinal Arteryphysiology; Retinal Veinphysiology;Ultrasonography, Doppler, Pulsed

Neal, M.; Cunningham, J. (1994): Modulation by endogenous ATP of the light-evoked release of ACh fromretinal cholinergic neurones. In: British journal of pharmacology, Jg. 113, H. 4, S. 1085–1087.Abstract The retina is an area of the central nervous system that possesses intrinsic

cholinergic neurones which release acetylcholine (ACh) in response to stimulationwith flickering light. Using an eye-cup preparation in anaesthetized rabbits we foundthat when the retina was exposed to the P2-purinoceptor antagonist, PPADS, thelight-evoked release of ACh was strikingly increased (by over 40%). In contrast,ATP reduced the light-evoked release of ACh by 20%. The inhibitory effect of ATPwas not due to its catabolism to adenosine because it was not affected by the A1-adenosine receptor antagonist, DPCPX, in combination with adenosine deaminase.The actions of both ATP and PPADS were completely blocked by strychnine. Weconclude that during physiological stimulation of the retina with light, ATP is co-released with ACh and partially inhibits ACh release by activating (with ACh) aninhibitory glycinergic feedback loop.

Schlagwörter Acetylcholinemetabolism; Adenosine Triphosphatephysiology; Animals;Feedbackphysiology; Neuronsmetabolismradiation effects; ParasympatheticNervous Systemmetabolism; Photic Stimulation; Pyridoxal Phosphateanalogs &derivativespharmacology; Rabbits; Receptors, GABA-Bmetabolism; Receptors,Purinergic P2antagonists & inhibitors; Retinacytologymetabolismradiation effects

Neal, M.; Cunningham, J.; Matthews, K. (1998): Selective release of nitric oxide from retinal amacrine andbipolar cells. In: Investigative ophthalmology & visual science, Jg. 39, H. 5, S. 850–853.Abstract PURPOSE: To investigate the cellular origin of nitric oxide released from the rabbit

retina in response to physiological stimulation with light. METHODS: The release ofnitric oxide from the retina was measured in rabbits anesthetized with urethane. Aneye-cup was prepared and was filled with Krebs-Ringer bicarbonate. After washingfor 45 minutes, 0.5 ml medium was placed in the eyecup. The medium wasreplaced every 10 minutes, and nitric oxide in the resultant samples was measuredusing nitrate reductase and a nitric oxide meter. RESULTS: In the unstimulateddark-adapted retina there was a spontaneous resting release of nitric oxide (1.20nmol/min). When the retina was stimulated for 10 minutes with flickering light therewas an increase in nitric oxide release to almost double the resting release.Stimulation of the retina for 10 minutes with continuous light produced a similarincrease in nitric oxide release. The exposure of the retina to L-amino-4-phosphonobutyrate (APB), which specifically blocks transmission between thephotoreceptors and the depolarizing bipolar cells, abolished the evoked release ofnitric oxide caused by flickering light and continuous light. In contrast, thenonselective excitatory amino acid antagonist cis-2,3-piperidinedicarboxylic acid(PDA) had no effect on the flicker-evoked release of nitric oxide, but it more thanhalved the release caused by continuous light. A similar differential effect onrelease was found with glycine, which abolished the nitric oxide release evoked withcontinuous light but did not affect the flicker-evoked release. The inhibitory effect ofglycine was blocked by strychnine. CONCLUSIONS: Nitric oxide was released inthe retina by flickering light and by continuous light, but the two types of stimulationcause nitric oxide release from different cells. Because in the rabbit retina nitricoxide synthase occurs mainly in a subpopulation of amacrine cells and a few bipolarcells, our pharmacologic results suggest that continuous light causes nitric oxiderelease from amacrine cells, whereas flickering light evokes nitric oxide releasefrom bipolar cells.

Schlagwörter Aminobutyric Acidspharmacology; Animals; Dark Adaptation; Enzyme

iLib08 - CitaviiLib08 - CitaviiLib08 - CitaviiLib08 - CitaviInhibitorspharmacology; Excitatory Amino Acid Agonistspharmacology; ExcitatoryAmino Acid Antagonistspharmacology; Glycinepharmacology;Interneuronsmetabolism; Light; Neuronsmetabolism; Nitric Oxidemetabolism; NitricOxide Synthaseantagonists & inhibitors; Photic Stimulation; PipecolicAcidspharmacology; Rabbits; Retinadrug effectsmetabolismradiation effects;omega-N-Methylargininepharmacology

Newman, Eric A. (2005): Calcium increases in retinal glial cells evoked by light-induced neuronal activity. In: TheJournal of neuroscience : the official journal of the Society for Neuroscience, Jg. 25, H. 23, S. 5502–5510.Online verfügbar unter doi:10.1523/JNEUROSCI.1354-05.2005.Abstract Electrical stimulation of neurons in brain slices evokes increases in cytoplasmic

Ca(2+) in neighboring astrocytes. The present study tests whether similar neuron-to-glial signaling occurs in the isolated rat retina in response to light stimulation.Results demonstrate that Müller cells, the principal retinal glial cells, generatetransient increases in Ca(2+) under constant illumination. A flickering light stimulusincreases the occurrence of these Ca(2+) transients. Antidromic activation ofganglion cell axons also increases the generation of Müller cell Ca(2+) transients.The increases in Ca(2+) transients evoked by light and antidromic stimulation areblocked by the purinergic antagonist suramin and by TTX. The addition ofadenosine greatly potentiates the response to light, with light ON evoking largeCa(2+) increases in Müller cells. Suramin, apyrase (an ATP-hydrolyzing enzyme),and TTX substantially reduce the adenosine-potentiated response. NMDA,metabotropic glutamate, GABA(B), and muscarinic receptor antagonists, incontrast, are mainly ineffective in blocking the response. Light-evoked Ca(2+)responses begin in Müller cell processes within the inner plexiform (synaptic) layerof the retina and then spread into cell endfeet at the inner retinal surface. Theseresults represent the first demonstration that Ca(2+) increases in CNS glia can beevoked by a natural stimulus (light flashes). The results suggest that neuron-to-gliasignaling in the retina is mediated by neuronal release of ATP, most likely fromamacrine and/or ganglion cells, and that the response is augmented underpathological conditions when adenosine levels increase.

Schlagwörter Action Potentials; Adenosineagonistspharmacology; AdenosineTriphosphatemetabolismpharmacology; Animals; Apyrasepharmacology;Axonsphysiologyradiation effects; Calciummetabolismphysiology; Light; Male;Neurogliacytologyphysiologyradiation effects;Neuronsmetabolismphysiologyradiation effects; Rats; Rats, Long-Evans;Receptors, Purinergicantagonists & inhibitors; Retinacytologyphysiologyradiationeffects; Retinal Ganglion Cellsphysiologyradiation effectsultrastructure;Suraminpharmacology; Tetrodotoxinpharmacology

Nguyen, Nhung X.; Horn, Folkert K.; Seitz, Berthold; Cursiefen, Claus; Martus, Peter; Langenbucher, Achim;Küchle, Michael (2002): Temporal contrast sensitivity using full-field flicker test (Erlangen flicker test) in patientsafter penetrating keratoplasty. In: Graefe's archive for clinical and experimental ophthalmology = Albrecht vonGraefes Archiv für klinische und experimentelle Ophthalmologie, Jg. 240, H. 6, S. 443–447. Online verfügbarunter doi:10.1007/s00417-002-0456-0.Abstract BACKGROUND: The purpose of this study was to evaluate the feasibility of

temporal contrast sensitivity testing using full-field flicker stimulation in patients afterpenetrating keratoplasty (PK) and to assess whether this method is influenced bypostoperative corneal topographic changes. METHODS: Forty-five patients (age46.5+/-14.2, median 47 years) who had undergone PK and 194 age-matchedcontrols were included in this study. The postoperative interval was 11.8+/-10.2months (median 9 months). Patients with pre-existing glaucoma or anypostoperative intraocular pressure elevation were excluded. The indications for PKwere keratoconus in 54% of cases, Fuchs' dystrophy in 38% and stromaldystrophies in 8%. Temporal contrast sensitivity was determined with sinusoidalflickering light (37.1 Hz) of constant mean photopic luminance (10 cd/m(2))

iLib08 - CitaviiLib08 - CitaviiLib08 - CitaviiLib08 - Citavipresented in a full-field bowl with an increasing threshold strategy. RESULTS: Meantemporal contrast sensitivity did not differ between patients after PK (1.49+/-0.13,range 1.26-1.78, confidence interval 1.45-1.53) and controls (1.55+/-0.17, range1.16-1.98, confidence interval 1.47-1.51). No significant correlation betweentemporal contrast sensitivity and visual acuity could be found in patients after PK orin normals ( r<0.2, P=0.3). In patients after PK, temporal contrast sensitivity wasstatistically independent of keratometric astigmatism ( r=0.3, P=0.7), topographicastigmatism ( r=0.3, P=0.4), spherical equivalent ( r=0.07, P=0.7), central cornealthickness ( r=-0.06, P=0.7) and time since operation ( r=-0.07, P=0.6).CONCLUSIONS: Temporal contrast sensitivity using full-field flicker stimulationseems to be feasible in patients after PK and does not depend on topographicchanges of the cornea. The results indicate that the full-field flicker test may behelpful as a supplementary means of detecting early glaucoma caused by ocularhypertension in patients after PK.

Schlagwörter Adult; Aged; Contrast Sensitivityphysiology; Corneaphysiology; CornealTopography; Female; Humans; Keratoplasty, Penetratingphysiology; Male; MiddleAged; Vision Tests

Nguyen, Thanh T.; Cheung, Ning; Wong, Tien Y. (2008): Influence of flickering light on the retinal vessels indiabetic patients: response to Mandecka et al. In: Diabetes care, Jg. 31, H. 6, S. e51; author reply e52. Onlineverfügbar unter doi:10.2337/dc08-0227.Schlagwörter Diabetic Retinopathyphysiopathology; Flicker Fusionphysiology; Humans; Light;

Photic Stimulation; Reaction Time; Retinal Vesselsphysiopathology; VisionDisordersphysiopathology

Nowak, J. Z.; Zurawska, E. (1989): Dopamine in the rabbit retina and striatum: diurnal rhythm and effect of lightstimulation. In: Journal of neural transmission, Jg. 75, H. 3, S. 201–212.Abstract In rabbits, dopamine levels in the retina, but not in the caudate nucleus, showed

clear diurnal rhythm, with high values seen in the light phase. Thirty min expositionof dark-adapted rabbits to day-light produced no changes in dopamine levels in theretina. In rabbits treated with alpha-methyl-p-tyrosine, the same light expositiondecreased the retinal amine level by 18%, while stimulation with intensive, flickeringlight significantly decreased the retinal dopamine content by 36%. Experimentsperformed at noon and midnight, under light or dark conditions, showed the retinaldopamine levels to be very similar in groups kept either at light or dark, irrespectiveof the time of the day, although in animals deprived of light the amine levels wereclearly lower than in those exposed to light, both at noon and midnight. Under allexperimental conditions there were no significant changes in dopamine level andutilization in the caudate nucleus. The isolated and superfused retina (preloadedwith [3H]-dopamine), when stimulated with flashes of white light (2 Hz, 10 min),released [3H]-radioactivity in a Ca2+-dependent manner. It is concluded that inrabbits, light enhances dopamine levels and utilization selectively in the retina, andthe observed diurnal changes in the amine metabolism are dependent on thepresence or absence of light, and not on the time of the day. The proposedphysiological role(s) of the retinal dopaminergic mechanisms is discussed.

Schlagwörter Animals; Caudate Nucleusmetabolismphysiology; Circadian Rhythm;Dopaminemetabolismphysiology; Female; Lighting; Male; Rabbits;Retinametabolismphysiology

Nuboer, J. F.; Coemans, M. A.; Vos, J. J. (1992): Artificial lighting in poultry houses: do hens perceive themodulation of fluorescent lamps as flicker. In: British poultry science, Jg. 33, H. 1, S. 123–133.Abstract 1. Many poultry houses are illuminated by fluorescent lamps which produce

discontinuous illumination with a frequency of either 100 or 120 Hz. 2. This studyinvestigated whether domestic fowls perceive this discontinuity as flicker by trainingtwo Leghorn hens to choose between a continuous and a discontinuous light, allother variables being identical. 3. The light-stimulus was either monochromatic with

iLib08 - CitaviiLib08 - CitaviiLib08 - CitaviiLib08 - Citavi100% sinusoidal modulation or a fluorescent lamp whose modulation frequencycould be electrically adjusted. 4. Each (correct) choice for the discontinuous lightwas followed by a 5 Hz higher frequency, whereas an incorrect choice was followedby a 10 Hz lower frequency. 5. On the basis of this principle the animals themselvesestablished the highest perceivable frequency of the discontinuous light, called theCritical Fusion Frequency (CFF), that they could discriminate from continuous light.6. These frequencies typically depend on the stimulus intensity increasing withincreasing intensities, until a maximum value is reached. 7. Two factors limited themagnitudes of the CFF's that were recorded: the maximum stimulus intensitiesproduced and variability in the chicken's response ("behavioural noise"). In spite ofthese constraints 105 Hz was established as the maximum CFF. 8. On the basis ofextrapolation it is concluded that the direct light from fluorescent lamps driven by 50Hz alternating current is seen by the chicken as flickering. 9. The results justifylarge-scale comparison of behaviour and production in poultry houses that areilluminated either by low-frequency or by high-frequency fluorescent lamps.

Schlagwörter Animals; Chickensphysiology; Conditioning, Classical; Female; Fluorescence;Housing, Animal; Lighting; Microcomputers; Visual Perception

Oomman, A.; Madhusudanan, M. (2001): Lorazepam: an adjuvant therapy in patients with seizure andheliotaxis. In: Neurology India, Jg. 49, H. 3, S. 317–319.Abstract Photosensitive epilepsy is a type of reflex epilepsy. Five percent of epileptics are

photosensitive, i.e. they show photoconvulsive response (PCR) during intermittentphotic stimulation. Patients with photogenic or photosensitive epilepsy haveseizures with flickering light. They also exhibit heliotaxis. Sodium valproate andethosuximide are the common drugs used. Even though benzodiazepines areuseful, the specific effect of lorazepam is not mentioned. We report 5 cases ofphotosensitive epilepsy with inadequate response to usual antiepileptic drugs whohad complete or near complete remission with lorazepam.

Schlagwörter Adolescent; Anticonvulsantstherapeutic use; Child; Epilepsy, Reflexdrugtherapyphysiopathology; Female; Humans; Lorazepamtherapeutic use; Male;Middle Aged; Sunlight

Pemp, Berthold; Garhofer, Gerhard; Weigert, Guenther; Karl, Katharina; Resch, Hemma; Wolzt, Michael;Schmetterer, Leopold (2009): Reduced Retinal Vessel Response to Flicker Stimulation but Not to ExogenousNitric Oxide in Type 1 Diabetes. In: Investigative ophthalmology & visual science. Online verfügbar unterdoi:10.1167/iovs.08-3260.Abstract Purpose: Various studies have shown that retinal vessels in patients with diabetes

mellitus have a reduced capacity to adapt to changes of perfusion pressure and tostimulation with flickering light. Structural and functional changes of retinal vesselsin diabetes could lead to a general reduction of vasodilator and/or vasoconstrictorcapacity. To gain more insight into this topic we compared the response of retinalvessel diameters to systemic glyceryl trinitrate (GTN) and stimulation with diffuseluminance flicker in patients with diabetes and healthy controls. Methods: 20patients with type 1 diabetes mellitus featuring no or mild non-proliferative diabeticretinopathy and 20 healthy and age-matched subjects were included in this study.The IMEDOS Dynamic Vessel Analyzer was used for measurement of diameters ofretinal arteries and veins. The response of diameters was measured continuouslyduring stimulation with flickering light as well as immediately after sublingualapplication of 0.8 mg of GTN. Results: The response of retinal vessels to flickeringlight was significantly reduced in patients with diabetes (arteries: 2.9% in diabetesversus 7.0% in controls, p < 0.002; veins: 4.6% in diabetes versus 6.8% in controls,p = 0.020). GTN-induced vasodilatation was not different between patients withdiabetes and healthy controls (p >/= 0.70). Conclusions: The present study confirmsreduced response of retinal vessels to stimulation with flickering light in diabetes.The response of retinal vessels to a direct NO-donor is, however, maintained. Thisindicates that abnormal flicker-induced vasodilatation in diabetes is not a

iLib08 - CitaviiLib08 - CitaviiLib08 - CitaviiLib08 - Citaviconsequence of generally reduced retinal vascular reactivity.

Peterson, M.; Ohzawa, I.; Freeman, R.: Neural and perceptual adjustments to dim light. In: Visual neuroscience,Jg. 18, H. 2, S. 203–208.Abstract At reduced luminance levels, the visual system integrates light over extended

periods of time. Although the general effects of this process are known, specificchanges in the visual cortex have not been identified. We have studied thephysiological changes that occur during a transition from high to low luminance bymeasurements of single neurons in the cat's primary visual cortex. Under low-luminance conditions, we find increased latencies, expanded temporal responses,and a loss of temporal structure. This results in temporal-frequency tuning curvesthat are peaked at relatively low frequencies. To examine parallel perceptualchanges, we compared perceived temporal frequency in human subjects underhigh- and low-luminance conditions. Low-luminance flickering patterns areperceived to modulate at relatively high rates. This occurs even though peaksensitivity is shifted to relatively low temporal frequencies. To explore further theperceptual component, we measured perceived temporal frequency in humansubjects with unilateral optic neuritis for whom optic nerve transmission is known tobe relatively slow and generally similar to the normal physiological state under lowluminance. These subjects also perceive relatively high modulation rates throughtheir affected eye. Considered together, these results demonstrate an inverserelationship between the physiological and the perceptual consequences of reducedstimulus luminance. This relationship may be accounted for by shifts of neuronalpopulation responses between high- and low-luminance levels.

Schlagwörter Animals; Cats; Dark Adaptation; Evoked Potentials, Visual; Humans; Light;Neuronsphysiology; Optic Neuritisphysiopathology; PerceptualDisordersphysiopathology; Psychophysics; Visual Cortexphysiology; VisualPerceptionphysiology

Petrenko, E. T.: [Effect of rhythmical light flickering on the stability of the human body]. In: Biofizika, Jg. 31, H. 4,S. 722–723.Abstract Influence of photostimulation upon the man's movements biomechanics

(stabilogram, goniogram, electromiogram etc) according to the one-leg toe balancemodel was investigated on 500 persons. Lowering of the exercise biomechanicalefficiency at the background of light gleams was established. Light gleams with thefrequency of 8-12 Hz which violated movement control processes (the correction ofthe body GWC) had maximal confusing effect.

Schlagwörter Biomechanics; Humans; Photic Stimulation; Postural Balance

Pevzner, L. Z.; Malinauskaite, O. L. (1978): Constant and flickering light stimulations produce similar effects onRNA content in visual cells. In: Acta histochemica, Jg. 63, H. 2, S. 288–291.Abstract Adult male rats were illuminated for 2 h with a constant or flickering light of 40 Lx

intensity; frequency of flickering was 2 Hz. By means of two-wave-length visiblecytospectrophotometry of gallocyanin-stained sections, it was shown that the lightstimulation resulted in a marked RNA accumulation in retina ganglion neurons andin the neurons of all the cell layers of visual cortex (with the only exception of thelayer VI). In the cells of perineuronal glia, a decrease of the RNA content per cellwas found in the retina while no changes were observed in the visual cortex. Effectsof constant and flickering light stimulations were qualitatively and quantitativelysimilar.

Schlagwörter Animals; Light; Male; Neurogliametabolismradiation effects;Neuronsmetabolismradiation effects; RNAmetabolism; Rats; Retinacytology;Spectrophotometry; Visual Cortexcytology

Piccardi, Marco; Ziccardi, Lucia; Stifano, Giovanna; Montrone, Lucrezia; Iarossi, Giancarlo; Minnella, Angelo etal. (2009): Regional cone-mediated dysfunction in age-related maculopathy evaluated by focal

iLib08 - CitaviiLib08 - CitaviiLib08 - CitaviiLib08 - Citavielectroretinograms: relationship with retinal morphology and perimetric sensitivity. In: Ophthalmic research, Jg.41, H. 4, S. 194–202. Online verfügbar unter doi:10.1159/000217723.Abstract PURPOSE: To assess regional cone-mediated function in age-related maculopathy

(ARM) by focal electroretinograms (FERGs), and to compare FERGs withmorphologic changes and perimetric sensitivity at corresponding locations.METHODS: Twenty-six ARM patients and 12 age-matched controls wereevaluated. FERGs were elicited by either a central (0-2.25 degrees , C) or aparacentral annular (2.25-9 degrees , PC) flickering (41 Hz) field, presented on alight-adapting background. Morphological changes (soft drusen and/or retinalpigment epithelium defects) at matched locations were assessed by fundusphotography and fluorescein angiography. Perimetric sensitivity was measured byOctopus 10 degrees program (tM2). RESULTS: When compared to controls, meanC and PC FERG amplitudes of patients were reduced (p < 0.01), and the mean PCFERG phase was delayed (p < 0.01). Both FERG delays and morphologic lesionstended to involve to a greater extent the PC compared to the C region. In the Cregion, perimetric losses were correlated with the extent of morphologic lesions (p <0.05). In the PC region, perimetric losses were correlated with FERG amplitudes (p< 0.05). CONCLUSIONS: In ARM, FERG losses are eccentricity-dependent, notquantitatively linked to retinal morphology, and correlated with perimetric losses,suggesting a heterogeneous dysfunction with loss of both C and PC perimetricsensitivities.

Poulton, E. C.; Kendall, P. G.; Thomas, R. J. (1966): Reading efficiency in flickering light. In: Nature, Jg. 209, H.5029, S. 1267–1268.Schlagwörter Humans; Light; Reading

Previc, Fred H.; McLin, Leon N.; Novar, Brenda J.; Kosnik, William: Comparison of violet versus red laserexposures on visual search performance in humans. In: Journal of biomedical optics, Jg. 10, H. 3, S. 34003.Online verfügbar unter doi:10.1117/1.1925207.Abstract Previous research suggests that the visual impairment of a violet laser is not highly

localized on the retina, because the lens absorbs most short-wavelength visiblelight and partly retransmits it as a diffuse fluorescence at approximately 500 nm.The present study investigated whether a 405 nm violet diode laser more greatlyimpairs visual search performance in humans than does a 670 nm red diode laser,depending on target eccentricity. Participants had to locate a square among 15diamonds spread throughout a visual search display while being exposed to a violetor red laser beam that was either continuous or flickering and presented either on-axis or 33 degrees off-axis. Whereas the continuous on-axis violet and red lasershad comparable effects on search performance when the target was located nearthe center of the beam, the violet laser disrupted processing of eccentric targetsmore than did the red laser. The search decrements were reduced for both laserswhen the beams were flickered or presented off-axis. Both the bluish appearanceand greater spatial spread of effect of the violet laser suggest that the uniqueimpairment caused by a violet laser beam derives from its induced lensfluorescence.

Schlagwörter Adult; Color; Humans; Lasers; Middle Aged; Pattern Recognition,Visualphysiologyradiation effects; Photic Stimulationmethods; PsychomotorPerformancephysiologyradiation effects

Purpura, K.; Tranchina, D.; Kaplan, E.; Shapley, R. M. (1990): Light adaptation in the primate retina: analysis ofchanges in gain and dynamics of monkey retinal ganglion cells. In: Visual neuroscience, Jg. 4, H. 1, S. 75–93.Abstract The responses of monkey retinal ganglion cells to sinusoidal stimuli of various

temporal frequencies were measured and analyzed at a number of mean lightlevels. Temporal modulation tuning functions (TMTFs) were measured at eachmean level by varying the drift rate of a sine-wave grating of fixed spatial frequencyand contrast. The changes seen in ganglion cell temporal responses with changes

iLib08 - CitaviiLib08 - CitaviiLib08 - CitaviiLib08 - Citaviin adaptation state were similar to those observed in human subjects and in turtlehorizontal cells and cones tested with sinusoidally flickering stimuli; "Weber's Law"behavior was seen at low temporal frequencies but not at higher temporalfrequencies. Temporal responses were analyzed in two ways: (1) at each light level,the TMTFs were fit by a model consisting of a cascade of low- and high-pass filters;(2) the family of TMTFs collected over a range of light levels for a given cell was fitby a linear negative feedback model in which the gain of the feedback wasproportional to the mean light level. Analysis (1) revealed that the temporalresponses of one class of monkey ganglion cells (M cells) were more phasic at bothphotopic and mesopic light levels than the responses of P ganglion cells. In analysis(2), the linear negative feedback model accounted reasonably well for changes ingain and dynamics seen in three P cells and one M cell. From the feedback model,it was possible to estimate the light level at which the dark-adapted gain of the conepathways in the primate retina fell by a factor of two. This value was two to threeorders of magnitude lower than the value estimated from recordings of isolatedmonkey cones. Thus, while a model which includes a single stage of negativefeedback can account for the changes in gain and dynamics associated with lightadaptation in the photopic and mesopic ranges of vision, the underlying physicalmechanisms are unknown and may involve elements in the primate retina otherthan the cone.

Schlagwörter Adaptation, Ocularphysiology; Animals; Electrophysiology; Feedback; FlickerFusion; Light; Linear Models; Macaca fascicularis; Retinaphysiology; RetinalGanglion Cellsphysiology; Synaptic Transmission; Visual Pathwaysphysiology

Roderick, Michael L. (2006): The ever-flickering light. In: Trends in ecology & evolution (Personal edition), Jg.21, H. 1, S. 3–5. Online verfügbar unter doi:10.1016/j.tree.2005.11.005.Abstract To date, ecologists involved in global change have focused on the consequences of

changes in air temperature. Concurrently, the amount of sunlight reaching thesurface of the Earth has been declining, resulting in so-called 'global dimming'.Now, Wild et al. and Pinker et al. have reported a reversal in this trend in someregions that has occurred over the past 15 years or so. These new findings,combined with earlier work, show that the transparency of the atmosphere can varysubstantially over periods of at least 20-50 years. Thus, the ecologicalconsequences of sustained trends in the occurrence of sunlight at the surface of theEarth need a more careful assessment than was previously thought.

Schlagwörter Air Pollutants; Atmosphereanalysis; Ecology; Environmental Monitoring;Greenhouse Effect; Models, Theoretical; Photosynthesis; Scattering, Radiation;Sunlight

Sandström, M.; Lyskov, E.; Berglund, A.; Medvedev, S.; Mild, K. H. (1997): Neurophysiological effects offlickering light in patients with perceived electrical hypersensitivity. In: Journal of occupational and environmentalmedicine / American College of Occupational and Environmental Medicine, Jg. 39, H. 1, S. 15–22.Abstract An increasing number of people in Sweden are claiming that they are

hypersensitive to electricity. These patients suffer from skin as well as neurologicalsymptoms when they are near computer monitors, fluorescent tubes, or otherelectrical appliances. Provocation studies with electromagnetic fields emitted fromthese appliances have, with only one exception, all been negative, indicating thatthere are other factors in the office environment that can effect the autonomicand/or central nervous system, resulting in the symptoms reported. Flickering lightis one such factor and was therefore chosen as the exposure parameter in thisstudy. Ten patients complaining of electrical hypersensitivity and the same numberof healthy voluntary control subjects were exposed to amplitude-modulated light.The sensitivity of the brain to this type of visual stimulation was tested by means ofobjective electrophysiological methods such as electroretinography and visualevoked potential. A higher amplitude of brain cortical responses at all frequencies ofstimulation was found when comparing patients with the control subjects, whereas

iLib08 - CitaviiLib08 - CitaviiLib08 - CitaviiLib08 - Citavino differences in retinal responses were revealed.

Schlagwörter Adult; Computer Terminals; Dermatitisdiagnosisetiologyphysiopathology;Electricityadverse effects; Electromagnetic Fieldsadverse effects;Electroretinography; Environmental Illnessdiagnosisetiologyphysiopathology;Evoked Potentials, Visual; Female; Humans; Lightdiagnostic use; Male; MiddleAged; Nervous System Diseasesdiagnosisetiologyphysiopathology

Saunders, Richard D.; Jefferys, John G. R. (2007): A neurobiological basis for ELF guidelines. In: Healthphysics, Jg. 92, H. 6, S. 596–603. Online verfügbar unter doi:10.1097/01.HP.0000257856.83294.3e.Abstract It is well understood that electric currents applied directly to the body can stimulate

peripheral nerve and muscle tissue; such effects can be fatal if breathing is inhibitedor ventricular fibrillation is induced. Exposure to extremely low frequency electricand magnetic fields will also induce electric fields and currents within the body, butthese are almost always much lower than those that can stimulate peripheral nervetissue. Guidance on exposure to such fields is based on the avoidance of acuteeffects in the central nervous system. This paper reviews the physiologicalprocesses involved in nerve cell excitability in the peripheral and central nervoussystem, and the experimental evidence for physiologically weak electric fieldeffects. It is concluded that the integrative properties of the synapses and neuralnetworks of the central nervous system render cognitive function sensitive to theeffects of physiologically weak electric fields, below the threshold for peripheralnerve stimulation. However, the only direct evidence of these weak field interactionswithin the central nervous system is the induction of phosphenes in humans--theperception of faint flickering light in the periphery of the visual field, by magneticfield exposure. Other tissues are potentially sensitive to induced electric fieldsthrough effects on voltage-gated ion channels, but the sensitivity of these ionchannels is likely to be lower than those of nerve and muscle cells specialized forrapid electrical signaling. In addition, such tissues lack the integrative properties ofsynapses and neuronal networks that render the central nervous system potentiallymore vulnerable.

Schlagwörter Animals; Body Burden; Central Nervous Systemphysiologyradiation effects;Computer Simulation; Electricity; Electromagnetic Fields; EnvironmentalExposureanalysisstandards; Humans; Models, Biological; Models, Neurological;Neurobiologymethodsstandards; Peripheral Nervous Systemphysiologyradiationeffects; Practice Guidelines as Topic; Radiation Dosage; RadiationMonitoringmethodsstandards; Radiation Protectionmethodsstandards; RadioWaves; Relative Biological Effectiveness; Reproducibility of Results; Sensitivity andSpecificity

Schmeisser, E. T. (1985): Flicker electroretinograms and visual evoked potentials in the evaluation of laser flasheffects. In: American journal of optometry and physiological optics, Jg. 62, H. 1, S. 35–39.Abstract Electroretinograms (ERG's) and visual evoked potentials (VEP's) were recorded

from four cynomolgus monkeys in response to a sinusoidally flickering argon laserbeam (514 nm) producing a 50-micron spot on the fovea. Super-position of a 20-Hztrain of six pulses of Q-switched (120 ns) frequency-doubled neodymium laser light(532 nm) at "safe" exposure energies in 250 ms had no significant effects on theERG (p greater than 0.05). The VEP was disrupted significantly (p less than 0.001)but demonstrated recovery within 500 ms of the initial pulse. Therefore, flash effectsof pulsed visible lasers at these doses on suprathreshold luminance processing areprobably limited only to the exposure period.

Schlagwörter Animals; Electroretinography; Evoked Potentials, Visual; Lasers; Macacafascicularis; Retinaphysiologyradiation effects

Shady, Sherif; MacLeod, Donald I. A.; Fisher, Heidi S. (2004): Adaptation from invisible flicker. In: Proceedingsof the National Academy of Sciences of the United States of America, Jg. 101, H. 14, S. 5170–5173. Onlineverfügbar unter doi:10.1073/pnas.0303452101.

iLib08 - CitaviiLib08 - CitaviiLib08 - CitaviiLib08 - CitaviAbstract Human ability to resolve temporal variation, or flicker, in the luminance (brightness)

or chromaticity (color) of an image declines with increasing frequency and is limited,within the central visual field, to a critical flicker frequency of approximately 50 and25 Hz, respectively. Much remains unknown about the neural filtering that underliesthis frequency-dependent attenuation of flicker sensitivity, most notably the numberof filtering stages involved and their neural loci. Here we use the process of flickeradaptation, by which an observer's flicker sensitivity is attenuated after prolongedexposure to flickering lights, as a functional landmark. We show that flickeradaptation is more sensitive to high temporal frequencies than is consciousperception and that prolonged exposure to invisible flicker of either luminance orchromaticity, at frequencies above the respective critical flicker frequency, cancompromise our visual sensitivity. This suggests that multiple filtering stages,distributed across retinal and cortical loci that straddle the locus for flickeradaptation, are involved in the neural filtering of high temporal frequencies by thehuman visual system.

Schlagwörter Adaptation, Psychological; Humans; Light

Shpak, A. A.; Rudneva, M. A.: [Critical frequency of light flickering rhythm reproduction in visual evokedpotentials: physiological essence of the method]. In: Vestnik oftalmologii, Jg. 107, H. 1, S. 42–45.Abstract Critical frequency of light flickering rhythm reproduction in visual evoked potentials

(CFLF) was studied in 25 patients (35 eyes) with partial optic nerve atrophy, 4patients (7 eyes) with moderate changes in the optic route suprachiasmal sections,and 23 normal subjects; automated static perimetry and visometry were carried outas well. CFLF was found reduced in the majority of patients with optic nerveatrophy, whereas in suprachiasmal involvement this parameter remained within thenormal range. CFLF values were in good correlation with vision acuity and lightsensitivity of visual field sites within the angle of 15 degrees from the center (thecorrelation was higher for foveal light sensitivity when it was expressed in relativeunits, and for light sensitivity of paracentral visual field sites when expressed inlogarithmic units). The authors come to a conclusion that CFLF functional andanatomic substrate is the foveal area cortical projection sites and, to a lesserdegree, cortical projection sites of visual field sites within 15 degrees from thecenter; in optic nerve atrophy CFLF values depend on the status of the optic nervesections (the axial bundle) corresponding to a certain visual field site.

Schlagwörter Adolescent; Adult; Child; Evoked Potentials, Visual; Female; Humans; Male; MiddleAged; Optic Atrophyphysiopathology; Perimetry; Visual Acuity

Siedek, H.; Hammerl, H.; Klein, K.; Studlar, P.; Bablik, C. (1965): [Autonomic changes under the influence offlickering light]. In: Verhandlungen der Deutschen Gesellschaft für Innere Medizin, Jg. 71, S. 961–965.Schlagwörter Autonomic Nervous Systemphysiology; Carotid Arteries; Eosinophils; Fatty

Acidsmetabolism; Fatty Acids, Nonesterifiedmetabolism; Humans; Light; Pulse

Soeta, Yoshiharu; Uetani, Shouji; Ando, Yoichi (2002): Propagation of repetitive alpha waves over the scalp inrelation to subjective preferences for a flickering light. In: International journal of psychophysiology : officialjournal of the International Organization of Psychophysiology, Jg. 46, H. 1, S. 41–52.Abstract Paired-comparison tests were performed to examine subjective preferences for a

flickering light. Electroencephalograms were then recorded from seven electrodes(10-20 system) during presentations of the most and least preferred flickering-lightconditions. As a way of investigating the flow of alpha waves on the scalp over boththe left and right hemispheres in relation to subjective preference, the alpha waveswere analyzed by means of the cross-correlation function (CCF). The maximumvalue of the CCF, /phi(tau)/(max), between the alpha waves measured at differentelectrodes and its delay time, tau(m), were analyzed. Results show that the mostpreferred flickering light has a significant larger /phi(tau)/(max) than the leastpreferred flickering light, and that /phi(tau)/(max) decreases with increasing distancebetween comparison (O(1) or O(2)) and test electrodes. On the other hand, the

iLib08 - CitaviiLib08 - CitaviiLib08 - CitaviiLib08 - Citavidelay time of the maximum value of the CCF, tau(m), increases with the distancebetween comparison and test electrodes.

Schlagwörter Adult; Algorithms; Alpha Rhythm; Electrodes; Electroencephalography; FunctionalLateralityphysiology; Humans; Male; Photic Stimulation; Scalpanatomy & histology

Sokol, S. (1973): Electroretinogram of the turtle retina obtained with flickering light. In: Vision research, Jg. 13,H. 1, S. 197–199.Schlagwörter Action Potentials; Animals; Dark Adaptation; Electroretinography; Flicker Fusion;

Photic Stimulation; Photoreceptor Cellsphysiology; Retinaphysiology; RetinalPigmentsphysiology; Spectrophotometry; Turtlesphysiology

Stockman, A.; MacLeod, D. I.; Lebrun, S. J. (1993): Faster than the eye can see: blue cones respond to rapidflicker. In: Journal of the Optical Society of America. A, Optics and image science, Jg. 10, H. 6, S. 1396–1402.Abstract Flickering lights that are detected by the blue cones of the human visual system

fuse to yield a steady sensation at much lower rates of flicker than do lights that aredetected by the red or green cones. Yet, although blue-cone-detected lightsflickering at 30-40 Hz appear to be steady, they are still able to interact with red- orgreen-cone-detected flickering lights to produce clearly detectable beats in the formof an amplitude modulation of the red- or green-cone flicker. Thus the blue conesproduce a viable high-frequency flicker signal, as do the red and green cones, butone that is normally lost before it reaches sensation. The temporal-frequencyresponse for the blue-cone beat interaction is similar in shape to the temporal-frequency response for directly detected red- or green-cone flicker. When measuredthrough the same pathway (which we identify as the luminance pathway, since it isable to transmit high-frequency flicker), the response of the blue cones seems to beas fast as that of the other cones.

Schlagwörter Color Perceptionphysiology; Flicker Fusionphysiology; Humans; Light; OcularPhysiological Phenomena; Photometry; Photoreceptor Cellsphysiology; SensoryThresholds

Suzumura, A. (1966): [Studies on the kinetic visual acuity; on the influence of flickering light upon the kineticvisual acuity]. In: Nippon ganka kiyo, Jg. 17, H. 2, S. 185–191.Schlagwörter Adult; Asthenopiaetiology; Female; Flicker Fusion; Humans; Occupational

Medicine; Vision, Ocularphysiology

Takahashi, T.; Tsukahara, Y.: Usefulness of blue sunglasses in photosensitive epilepsy. In: Epilepsia, Jg. 33, H.3, S. 517–521.Abstract The suppressive effect of sunglasses upon photoparoxysmal responses (PPRs)

elicited by 15-Hz flicker stimuli with a low luminance of nearly 10 nits was studied ineight patients with photosensitive epilepsy. Using three commercially availablesunglasses of neutral density (ND), blue, and brown, the influence upon generalizedPPRs elicited by a flickering dot pattern (FDP) and red flicker (RF) stimuli wasseparately examined in six patients; the luminance of the visual stimuli decreasedfrom roughly one-fifth (ND and brown sunglasses) to one-tenth (blue sunglasses).With FDP stimulation, four of the six patients wearing each of the three sunglasseshad no provocation of PPRs, whereas two of the six patients had provocation ofgeneralized PPRs with all of the sunglasses. With RF stimulation, two of the sixpatients wearing ND sunglasses had provocation of generalized PPRs; three of thesix patients wearing brown sunglasses had similar provocation; in contrast, none ofthe six patients showed provocation of PPRs while wearing blue sunglasses. Theseresults suggest that the suppressive effect of the three sunglasses on FDPstimulation is mainly due to a luminance diminution, whereas that of bluesunglasses on RF stimulation is produced by an inhibitory effect of shortwavelengths and possibly by a luminance diminution. Thus, blue sunglasses arethought to be useful in the treatment of patients with photosensitive epilepsy.

Schlagwörter Adolescent; Color; Electroencephalography;

iLib08 - CitaviiLib08 - CitaviiLib08 - CitaviiLib08 - CitaviEpilepsyetiologyphysiopathologyprevention & control; Eyeglasses; Female;Humans; Lightadverse effects; Male; Photic Stimulation

Takahashi, T.; Tsukahara, Y. (1979): Influence of red light and pattern on photic driving. In: The Tohoku journalof experimental medicine, Jg. 127, H. 1, S. 45–52.Abstract The photic drivings (PDs) in response to the following visual stimuli were studied in

108 cases, of which 84 (78%) were epileptics; ages ranged from 5 to 57 years old.An intermittent photic stimulation (IPS) of 5 cycles/sec by a stroboscopic light wasgiven to the subjects with eyes closed and open. Following these stimuli, red-flickerand flickering-pattern of 5 cycles/sec and 20 cd/m2 were given successively to thesubjects with eyes open using a "visual stimulator". The PDs evoked by IPS to theeyes closed and those by red-flicker were similar in the wave form and amplitude. Inmost of the cases, however, both stimuli failed to evoke apparent PDs (over 25muV in amplitude), i.e., in 81% and 72%, respectively. IPS to the eyes open andflickering-pattern showed comparable effects in evoking PDs; they evoked highamplitude PDs (over 50 muV in amplitude) with a frequency of 19% by the formerand 28% by the latter. In 95 out of 108 cases, both IPS to the eyes closed and red-flicker failed to evoke apparent PDs. In rare cases, IPS to eyes closed evoked highamplitude PDs; in 7 out of these 8 cases, red-flicker also evoked high amplitudePDs. In 18 out of 20 cases in which high amplitude PDs were evoked by IPS to theeyes open, flickering-pattern was also effective in evoking high amplitude PDs.Based on these findings, similarities between IPS to the eyes closed and red-flicker,and similarities between IPS to the eyes open and flickering-pattern in evoking PDsare discussed. It is concluded that flickering-pattern and red-flicker are superior toIPS to the eyes open and closed, respectively, for examining the low frequencyPDs.

Schlagwörter Adolescent; Adult; Child; Child, Preschool; Color; Electroencephalography;Epilepsyphysiopathology; Female; Humans; Male; Middle Aged; PhoticStimulationmethods

Takahashi, T.; Tsukahara, Y. (1998): Pocket Monster incident and low luminance visual stimuli: specialreference to deep red flicker stimulation. In: Acta paediatrica Japonica; Overseas edition, Jg. 40, H. 6, S.631–637.Abstract On the evening of 16 December 1997 approximately 700 people around the nation

(mostly children) were rushed to hospitals and treated for seizure symptoms. Theyoungsters had been watching the vastly popular TV animated cartoon seriesPocket Monsters (Pokemon). We designated those individuals as a main group,who presumably had simultaneous occurrence of visually induced seizures. Follow-up studies revealed that 5-10.4% of Pokemon viewers had various minor symptomsnot requiring hospital treatment. We designated those as a subgroup. Due to anofficial report regarding the problematic TV scene as a low luminance, 12 Hzalternating red/blue stimulus, we attempted an accounting of the Pokemon incident,with regard to the main group in particular, on the basis of electroencephalographicactivation by use of low luminance 15 Hz deep red flicker stimulation. In order toexplain the entire Pokemon incident, including symptoms experienced byindividuals of the subgroup, we considered the possibility that some healthyyoungsters may have latent photosensitivity and we thought that such a sensitivitymight be disclosed by use of low luminance deep red flicker stimulation which ismore provocative of photoparoxysmal response than ordinary high luminancestroboscopic intermittent photic stimulation. For prevention of visually inducedseizures by TV viewing, we stress that care should be taken to test not only redflicker but also flickering geometric pattern stimuli.

Schlagwörter Cartoons as Topic; Child; Color; Electroencephalography; Female; Humans; Japan;Male; Photic Stimulationadverse effects; Seizuresetiologyphysiopathology;Television

iLib08 - CitaviiLib08 - CitaviiLib08 - CitaviiLib08 - CitaviTakahashi, T.; Tsukahara, Y.; Kaneda, S. (1981): Influence of pattern and red color on the photoconvulsiveresponse and the photic driving. In: The Tohoku journal of experimental medicine, Jg. 133, H. 2, S. 129–137.Abstract Patients, 232 epileptics and 98 nonepileptics, were examined for photoconvulsive

responses and photic driving, by using a stroboscope with a) a printed pattern (dotsor grating) and b) a red plastic plate. The stimuli given were (1) dot pattern 5 HzIPS, (2) red 5 Hz IPS, (3) grating pattern 15 Hz IPS, and (4) red 15 Hz IPS, witheyes open. Photoconvulsive responses evoked by (3) and (4) were 6.6% and 5.1%,respectively, which were significantly higher than those obtained from a controlgroup flickered with ordinary white light, 15 Hz IPS, (1.1% and 0.9%, with eyesopen and closed, respectively). High amplitude photic driving over 50 microVevoked by (1) occurred in 34.9% of the patients and by (2) 22.7%; these weresignificantly higher than in the control group with ordinary white flicker (12.5% and5.2%). Similar stimuli of (1) to (4) with a constant brightness of 20 cd/m2 providedby a visual stimulator SLS-5100 were given in the same way. Photoconvulsiveresponse evoked by 15 Hz flickering grating pattern occurred in 7.8% and by 15 Hzred flicker in 8.1%; the rate being slightly higher than, but not significantly differentfrom, the above results. High amplitude photic driving evoked by 5 Hz flickering dotpattern and 5 Hz red flicker were 29.3% and 21.2%, respectively. These valueswere slightly lower than, but not significantly different from, the above results. It wasconcluded that the flicker stimulation with either pattern or red color is more potentin eliciting photoconvulsive responses (15 Hz) and photic driving responses (5 Hz)than conventional flicker. Furthermore, patterned IPS and red IPS showed almostthe same activation effect on photoconvulsive responses and high amplitude photicdriving as that of the comparable stimuli provided by a visual stimulator SLS-5100.

Schlagwörter Adolescent; Adult; Aged; Child; Color; Electroencephalography;Epilepsyphysiopathology; Female; Humans; Male; Middle Aged; Photic Stimulation;Seizuresetiology

Terahata, K.; Shimada, H. (1970): [Light stimulation apparatus flickering at irregular intervals]. In: Igaku toseibutsugaku. Medicine and biology, Jg. 80, H. 5, S. 247–252.Schlagwörter Electroencephalographyinstrumentation; Light

UTINA, Ia; NECHAEVA, N. V.; BRODSKII, V. Ia (1960): [RNA in ganglion cells of the retina in frogs in darknessand after the illumination with a constant flickering light.]. In: Biofizika, Jg. 5, S. 749–750.Schlagwörter Adaptation, Ocular; Light; RNAmetabolism; Retinametabolism

van der Horst, G. J.; Muis, W. (1969): Hue shift and brightness enhancement of flickering light. In: Visionresearch, Jg. 9, H. 8, S. 953–963.Schlagwörter Color Perception; Flicker Fusion; Humans; Light; Photometry; Spectrum Analysis

Vítová, Z. (1973): Responsiveness to flickering light in waking and sleeping infants. In: PhysiologiaBohemoslovaca, Jg. 22, H. 2, S. 147–152.Schlagwörter Age Factors; Brain; Electroencephalography; Evoked Potentials; Eye Movements;

Humans; Infant; Light; Sleep; Sleep, REM; Wakefulness

Vítová, Z. (1973): Cerebral responses to flickering light in clinical research. In: Activitas nervosa superior, Jg. 15,H. 1, S. 63–69.Schlagwörter Adolescent; Brainphysiology; Brain Diseasesphysiopathology; Cerebral

Palsyphysiopathology; Child; Child, Preschool; Electroencephalography; EvokedPotentials; Female; Humans; Hydrocephalusphysiopathology;Hypothyroidismphysiopathology; Infant; Male; Photic Stimulation; Sleep, REM;Thalamusphysiopathology; Wakefulness

Wang, J.; Langer, S. (1997): A brief review of human perception factors in digital displays for picture archivingand communications systems. In: Journal of digital imaging : the official journal of the Society for ComputerApplications in Radiology, Jg. 10, H. 4, S. 158–168.

iLib08 - CitaviiLib08 - CitaviiLib08 - CitaviiLib08 - CitaviAbstract The purpose of this review is to further inform radiologists, physicists, technologists,

and engineers working with digital image display devices of issues related to humanperception. This article will briefly review the effects of several factors in humanperception that are specifically relevant to a digital display environment. Thesefactors include the following: the spatial and contrast resolution of the displaydevice; background luminance level and luminance range of the display system;brightness uniformity; extraneous light in the reading room; displayed field size;viewing distance; image motion and monitor flickering; signal to noise ratio of thedisplayed image; magnification functions; and the user interface. After reviewing theperception study results, a checklist of desirable features and quality assuranceissues for a digital display workstation are presented as an appendix.

Schlagwörter Computer Terminalsstandards; Data Display; Humans; Image Processing,Computer-Assistedstandards; Quality Control; Radiology InformationSystemsstandards; User-Computer Interface; Visual Perception

Wang, L.; Bill, A. (1997): Effects of constant and flickering light on retinal metabolism in rabbits. In: Actaophthalmologica Scandinavica, Jg. 75, H. 3, S. 227–231.Abstract PURPOSE: To characterize the glucose metabolism in the rabbit retina.

METHODS: An artery and a vortex vein were cannulated. Arteriovenous differencesin oxygen, lactate and glucose concentrations, and blood flow were determinedduring either 1) darkness and light, or 2) light and 4 Hz flickering light. RESULTS: Indarkness, oxygen consumption, glucose consumption, and lactate formation were0.122 +/- 0.014, 0.204 +/- 0.015 and 0.160 +/- 0.023 micromol/min (mean +/- SE),respectively. Constant light reduced oxygen consumption insignificantly, and had noeffect on glucose consumption. Hyperoxia did not affect the lactate formation.Flickering light increased the glucose consumption and lactate formation by 15-20%. CONCLUSIONS: In rabbits, 10% of the glucose consumed is oxidized, 40-50% is metabolized to lactate and the rest is used for other purposes. Theglycolysis is primarily aerobic. Flickering light increases the glucose metabolism,constant light having little effect.

Schlagwörter Adaptation, Ocularphysiology; Animals; Blood Flow Velocityradiation effects;Glucosemetabolism; Glycolysisradiation effects; Lactic Acidbiosynthesis; Light;Oxygenmetabolism; Oxygen Consumptionradiation effects; Photic Stimulation;Rabbits; Retinametabolismradiation effects; Retinal Arteryphysiology; RetinalVeinphysiology

Weiler, R.; Akopian, A. (1992): Effects of background illuminations on the receptive field size of horizontal cellsin the turtle retina are mediated by dopamine. In: Neuroscience letters, Jg. 140, H. 1, S. 121–124.Abstract Intracellular recordings from luminosity-type horizontal cells of the turtle retina were

used to analyze the effects of steady and flickering background illumination on thesize of their receptive fields. Both types of background illumination reduce the sizeof the receptive field to about the same extent. The reduction seems largely due anincrease in the coupling resistance between horizontal cells. The effects of bothtypes of background illumination are sensitive to the dopamine antagonistfluphenazine. This suggests that steady and flickering illuminations stimulate therelease of endogenous dopamine.

Schlagwörter Animals; Dopaminephysiology; Electrophysiologymethods;Fluphenazinepharmacology; Light; Photic Stimulation; Retinacytologydrugeffectsphysiology; Turtles; Visual Fields

Weiner, A.; Sandberg, M. A. (1991): Normal change in the foveal cone ERG with increasing duration of lightexposure. In: Investigative ophthalmology & visual science, Jg. 32, H. 10, S. 2842–2845.Abstract Foveal cone electroretinograms (ERG) were elicited with a stimulator-

ophthalmoscope from 24 normal subjects with a 4 degrees stimulus flickering at 42Hz and centered within a 12 degrees steady surround. The stimulus and surroundwere presented at retinal illuminances of 4.8 log td and 5.5 log td, respectively, to

iLib08 - CitaviiLib08 - CitaviiLib08 - CitaviiLib08 - Citavifacilitate visualization of the fundus. Several consecutive averaged responses wereevaluated to determine whether increasing duration of light exposure causes anincrease in amplitude, as previously found for the full-field cone ERG. On average,amplitude increased by 27% over time, and the linear regression of amplitude onrecording number accounted, on average, for 42% of the amplitude variabilitybetween consecutive responses. Two subjects had amplitudes that were initiallysubnormal, based on previously published norms, but that value increased to withinthe normal range in subsequent recordings. These findings show that a significantchange in the cone ERG occurs in the fovea with increasing duration of lightexposure at these retinal illuminances, and suggest that, when the stimulator-ophthalmoscope is used, consecutive foveal cone ERGs should be obtained frompatients with suspected macular disease to avoid a false diagnosis of retinalmalfunction.

Schlagwörter Adolescent; Adult; Child; Electroretinography; Fovea Centralisphysiology; Humans;Middle Aged; Photic Stimulation; Photoreceptor Cellsphysiology; RetrospectiveStudies

West, R. W.; Penisten, D. K. (1996): The effect of color on light-induced seizures: a case report. In: Optometryand vision science : official publication of the American Academy of Optometry, Jg. 73, H. 2, S. 109–113.Abstract BACKGROUND. Two to four percent of epileptics have their seizures triggered by

flickering light, an effect which may be wavelength-dependent. We evaluated apatient with a long-standing history of light-induced petit mal seizures to determine ifthe seizures were triggered more effectively by a particular range of wavelengthsand to determine whether this information could be used in the optometricmanagement of such patients. METHODS. Flickering lights of different wavelengthsbut equal luminance were presented while the patient's electroencephalogram(EEG) and subjective reports were monitored. RESULTS. The EEG results werenot significantly different for different wavelengths, but the patient reported thatlonger wavelength light induced stronger seizures more consistently. Based onthese results we concluded that the patient might benefit from spectacles tinted toexclude transmission of red light. The patient was given 4 pairs of 85% transmissionspectacles, which differed only in lens tint (red, yellow, green, and blue), to try overa period of time. The patient felt that the tinted lenses were not dark enough todecrease his seizures effectively and he has opted to wear standard sunglasses.CONCLUSIONS. We feel this case shows that patients with light-induced seizurescan benefit from optometric consultation. Because the patient's subjective reportidentified the clearest wavelength effect, we feel that it is reasonable for the generalpractitioner to suggest deeply tinted lenses to reduce the frequency of seizures inthese patients.

Schlagwörter Adult; Color; Electroencephalography; Eyeglasses; Humans; Lightadverse effects;Male; Seizuresphysiopathologyprevention & control

Wolfson, S. S.; Graham, N. (2000): Exploring the dynamics of light adaptation: the effects of varying theflickering background's duration in the probed-sinewave paradigm. In: Vision research, Jg. 40, H. 17, S.2277–2289.Abstract In the probed-sinewave paradigm, threshold for detecting a probe is measured at

various phases with respect to a sinusoidally-flickering background. Here we varythe duration of the flickering background before (and after) the test probe ispresented. The adaptation is rapid; after approximately 10-30 ms of the flickeringbackground, probe threshold is the same as that on a continually-flickeringbackground. It is interesting that this result holds at both low (1. 2 Hz) and middle(9.4 Hz) frequencies because at middle frequencies (but not at low) there is a dc-shift, i.e. probe threshold is elevated at all phases relative to that on a steadybackground (of the same mean luminance). We compare our results to predictionsfrom Wilson's model [Wilson (1997), Visual Neuroscience, 14, 403-423; Hood &Graham (1998), Visual Neuroscience, 15, 957-967] of light adaptation. The model

iLib08 - CitaviiLib08 - CitaviiLib08 - CitaviiLib08 - Citavipredicts the rapid adaptation, and the dc-shift, but not the detailed shape of theprobe-threshold-versus-phase curve at middle frequencies.

Schlagwörter Adaptation, Ocularphysiology; Contrast Sensitivityphysiology; Flicker Fusion;Humans; Mathematical Computing

Wolfson, S. Sabina; Graham, Norma (2006): Forty-four years of studying light adaptation using the probed-sinewave paradigm. In: Journal of vision, Jg. 6, H. 10, S. 1026–1046. Online verfügbar unter doi:10.1167/6.10.3.Abstract Here we examine results from 44 years of probed-sinewave experiments

investigating the dynamics of light adaptation. We also briefly examine four modelsthat have been tested against the results. In these experiments, detection thresholdis measured for a test stimulus superimposed at various times (phases) on asinusoidally flickering homogeneous background. The results can be plotted asprobe-threshold versus phase curves. Overall, the curves from different laboratoriesare remarkably similar given the substantial differences in experimental parameters.However, at medium frequencies of background flicker, there are some differencesbetween the majority of the studies and a minority of two. An examination of the fullset of results suggests that the differences are not as significant as they first appearand that the experimental condition leading to the differences is the use of longwavelength light in the two minority studies. Of the four models that have beentested, two fail to predict important features of the results, another is criticallydependent on a mechanism unlikely to exist in the appropriate physiology, and thelast seems quite promising.

Schlagwörter Adaptation, Ocular; History, 20th Century; History, 21st Century; Humans; Models,Biological; Psychologyhistory; Psychophysics; Sensory Thresholds

Wu, S.; Burns, S. A.; Reeves, A.; Elsner, A. E. (1996): Flicker brightness enhancement and visual nonlinearity.In: Vision research, Jg. 36, H. 11, S. 1573–1583.Abstract The purpose of this study was to investigate the nonlinear mechanism underlying

brightness enhancement, in which a flickering stimulus appears brighter than asteady stimulus of equal mean luminance. The flickering and matching stimuli weretemporally alternated. Both were cosine windowed to minimize the potential effectsof temporal transients. Subjects adjusted the amplitude of the matching stimulus tomatch it in brightness to the flickering stimulus. The temporal frequency,modulation, and waveform of the flickering stimulus were varied. With sinusoidalflicker, brightness enhancement increased with increasing modulation at allfrequencies, peaking at about 16 Hz at full modulation. The results were modeledby a broad temporal filter followed by a single accelerating nonlinearity. The derivedtemporal sensitivity of the early filter inferred from brightness enhancementdecreased more slowly at high frequencies than the filter(s) inferred from flickermodulation thresholds. With low frequency sawtooth flicker, brightnessenhancement was phase-dependent at low, but not at high modulations, suggestingthat multiple neural mechanisms may also be involved in addition to an earlynonlinearity.

Schlagwörter Female; Flicker Fusionphysiology; Humans; Light; Male; Models, Biological;Photometry; Sensory Thresholdsphysiology; Time Factors