virtually all sensory experience occurs in the context of active behaviors 12 345
Post on 15-Jan-2016
220 Views
Preview:
TRANSCRIPT
Virtually all sensory experience occurs in the context of active behaviors
1 2
3 4 5
• In many cases, sensing actions are central to the task of collecting accurate information about the environment.
• Sensing actions involve moving the stimulus object with respect to the sense organ, or perturbing the stimulus object in some way.
Thesis: sensing and “sensing actions” are processed in a concerted fashion
• Knowledge of sensing actions can be critical to the interpretation of sensory signals.
http://webvision.med.utah.edu
Specializations of the retinal fovea: densest packing of photoreceptors and lowest convergence of
photoreceptors onto ganglion cells
http://webvision.med.utah.edu
Specializations of the retinal fovea: displacement of inner retina
http://webvision.med.utah.edu
Specializations of the retinal fovea: absence of retinal vasculature
Hans-Werner Hunziker, (2006) “Im Auge des Lesers”, Transmedia Stäubli Verlag Zürich
Acute vision only occurs within a few degrees of the fovea
Saccadic eye movements bring objects into the fovea
We make a saccade 2-3 times per second.
The problem with eye movements #1:
Solution: the visual system interprets visual signals in the context of knowledge about coordinated eye movements.
Problem: eye movements create fictive motion of the image on the retina.
-- Hermann von Helmholtz, Physiologische Optiktrans. William James, The Principles of Psychology
The problem with eye movements #2:
Solution: visual signals are suppressed during saccades.
Problem: eye movements blur the image on the retina.
cat LGN, spontaneous saccades in the dark, avg of 71 cells Lee & Malpeli, J. Neurophysiol. 1998
The problem with eye movements #3:
Stein & Stanford 2008
Solution: eye position modifies the auditory receptive fields of superior colliculus neurons.
Problem: eye movements change the relationship between the visual world and the head, so visual and auditory maps are misaligned.
The problem with head movements:
Boyden, Katoh, & Raymond Annu. Rev. Neurosci. 2004
Solution: The eyes move precisely to oppose head movement. This is called the vestibular-ocular reflex (VOR).
The gain of the VOR can be changed by pairing head movement with stimulus movement.
Problem: head movements cause a stationary object to move out of the fovea.
Sabin, Macpherson , & Middlebrooks, Hearing Res. 2004 human psychophysics
Hearing: localization acuity depends on source position
Thus, head movements can “foveate” an auditory stimulus.
Hearing: self-sound is filtered differently from non-self sound
A giant neuron conveys corollary discharge to auditory processing centers and transiently “deafens” the cricket.
Hedwig & Poulet Science 2006
CDI morphology:
Olfaction: sniffing is an active process
Kepecs, Uchida, & Mainen J. Neurophysiol. 2007
Novel odors can trigger rapid increases in sniff rate
rat Wesson et al., PloS Biology 2008
2-alternative forced-choice w/ water reward Uchida & Mainen, Nat. Neurosci. 2003
A two-alternative forced-choice paradigm for odor discrimination
Wesson et al., Chem. Senses 2008
Sniff rate increases in anticipation of an odor
mouse 1
mouse 2
mouse 3
2-alternative forced-choice w/ water reward
Rapid sniffing attenuates olfactory receptor neuron inputto the olfactory bulb
head-fixed rat, rat calcium imaging w/ OGB Verhagen et al., Nat. Neurosci. 2007
Verhagen et al., Nat. Neurosci. 2007
Effects of rapid sniffing are bottom-up (not top-down)
head-fixed rat, rat calcium imaging w/ OGB
Kleinfeld, Ahissar, & Diamond, Curr. Opin. Neurobiol. 2006Adapted from Fee, Mitra, & Kleinfeld, J. Neurophysiol. 1997
Somatosensation: rodent whisking as a model for active encounters with somatosensory stimuli
The whisker pad has a large representation in the somatosensory cortex of the rodent
Petersen Pflugers Arch. 2003
Somatosensory cortex contains “reference signals” about whisker motion
Crochet & Petersen, Nat. Neurosci. 2006whole-cell patch-clamp recording from awake mouse
Responses to whisker deflection in barrel cortexdepend on whether the animal is actively whisking
Ferezou, Petersen et al, Neuron 2006
Kleinfeld, Ahissar, & Diamond, Curr. Opin. Neurobiol. 2006
Somatosensory and motor circuits are linked by sensorimotor loops
1°
2°
3°
4°
motor neurons
ext
rale
mn
isca
l (to
uch
)
lem
nis
cal (
both
)
para
lem
nisc
al (m
otio
n)
Electrosensation: sensory exotica
Gnathonemus petersii
see e.g., Sensory Exotica: A World beyond Human Experience, by H. Hughes (MIT Press, 2001)
electric organ discharge command nucleus
electric organ electrosensory receptor neurons
electric organ discharge
(EOD)
fish
water
adapted from Bell J. Exp. Biol. 1989
electrosensory lobe(ELL)
higher brain regions
Active sensing in electrosensation
The fish actively produces electric organ discharges (EODs).
Objects in the water perturb the amplitude of the electric field.
This changes the latency of spikes in electrosensory afferents.
Active sensing in electrosensation
electric organ discharge command nucleus
electric organ electrosensory receptor neurons
electric organ discharge
(EOD)
electric organ corollary discharge
(EOCD)
fish
water
adapted from Bell J. Exp. Biol. 1989
electrosensory lobe(ELL)
higher brain regions
intramuscularcurare
local lidocaine
metalliccurrent sink
EOD command (effect on the electric organ is blocked with curare)
command alone
command alone
command + electrosensory stimulus 1.5 msec later
80 msec
(9 min)
Bell Brain Res. 1986
Plastic responses to corollary discharge
1 min
recording from mormyrid ELL
electric organ discharge command nucleus
electric organ electrosensory receptor neurons
electric organ discharge
(EOD)
electric organ corollary discharge
(EOCD)
fish
water
adapted from Bell J. Exp. Biol. 1989
proprioceptors
electrosensory lobe(ELL)
higher brain regions
Bastien J. Comp. Physiol. 1995
Plastic responses to proprioceptive stimuli
recording from gymnotid ELL
top related