alcohol’s effect on inhibitory mechanisms of visual attention by ben abroms

Alcohol’s effect on Inhibitory Alcohol’s effect on Inhibitory Mechanisms of Visual Mechanisms of Visual

AttentionAttention

by Ben Abromsby Ben Abroms

My BackgroundMy Background

• Born: Toronto, CanadaBorn: Toronto, Canada•Dual CitizenshipDual Citizenship

• Undergrad: University of Western Undergrad: University of Western OntarioOntario

•Began focus on cognitive processesBegan focus on cognitive processes

• Grad School: University of KentuckyGrad School: University of Kentucky•Master’s in Animal CognitionMaster’s in Animal Cognition

•Ph.D. in Cognitive NeurosciencePh.D. in Cognitive Neuroscience

OverviewOverview

• Acute Alcohol IntoxicationAcute Alcohol Intoxication•Drunk DrivingDrunk Driving

•Why study acute alcohol effects on attention?Why study acute alcohol effects on attention?

• AttentionAttention•Attention and inhibitionAttention and inhibition

• 2 Cognitive Tasks2 Cognitive Tasks• IOR modelIOR model

•Delayed Ocular Response Task Delayed Ocular Response Task

What we know about drugs.What we know about drugs.

Mmm-Mmm-KayKay

Acute Alcohol IntoxicationAcute Alcohol Intoxication

• Drunk DrivingDrunk Driving – $9 – $9 billion a year billion a year (NCPA, 2001)(NCPA, 2001). .

• Majority of those with Majority of those with DUI in past 12 DUI in past 12 months not months not dependant or abusers dependant or abusers (Caetano & McGrath, 2005).(Caetano & McGrath, 2005).

Over 500 000 people Over 500 000 people injured per year!injured per year!


Fatal Fatal Crashes:Crashes:BACBAC IncreaseIncrease

0.05-0.090.05-0.09 11X11X

0.1-0.140.1-0.14 48X48X

>0.15>0.15 380X380X

(Zador, 1991)(Zador, 1991)


• Drunk Driving Drunk Driving (continued)(continued)

(National Highway Traffic and Safety Admin., 2004)(National Highway Traffic and Safety Admin., 2004)

Total Traffic Total Traffic DeathsDeaths

Alcohol Alcohol RelatedRelated PercentagePercentage

CaliforniaCalifornia 4,2154,215 16261626 3939

KentuckyKentucky 928928 276276 3030

USAUSA 42,64342,643 17,01317,013 4040


• Why does Why does increasing BAC increasing BAC result in result in increased increased accident risk? accident risk?

• Cognition & Cognition & BehaviorBehavior


•We also know that…….We also know that…….•Alcohol increases risky behavior Alcohol increases risky behavior (Piombo (Piombo

& Piles, 1996)& Piles, 1996)..•Alcohol Myopia Alcohol Myopia (Steele & Josephs, 1990).(Steele & Josephs, 1990).

•Disinhibition Disinhibition (Fillmore, 2003).(Fillmore, 2003).

•The more complex the more impaired The more complex the more impaired by alcohol by alcohol (Maylor, Rabbitt, & James 1992)(Maylor, Rabbitt, & James 1992)..

•Alcohol slows Alcohol slows information processinginformation processing (Halloway, 1995).(Halloway, 1995).

Alcohol and Information Alcohol and Information ProcessingProcessing

• Information processing comprised of Information processing comprised of three stages three stages (eg. Welford, 1952).(eg. Welford, 1952).

•Stimulus IdentificationStimulus Identification

•Response SelectionResponse Selection

•Response ExecutionResponse Execution

•Attention is more than just a spotlight!Attention is more than just a spotlight!

AttentioAttentionn

AttentionAttention

•Attention is an important component of information processing.

•Attention directs cognitive resources to relevant stimuli and away from irrelevant stimuli (Pashler, 1998).

• Impairment of attention = reduction in the capacity of information processing.

AttentionAttention

• Vague ConceptVague Concept

• Internal vs. Internal vs. ExternalExternal

•Controlled vs. Controlled vs. AutomaticAutomatic

•Relation to Relation to Working MemoryWorking Memory

Attention and InhibitionAttention and Inhibition

•Attention depends on inhibitory influences.

•Protection from interference

•Attention allocation (Bjorklund & Harnishfeger, 1995)

•An Example: Negative Priming

Attention and InhibitionAttention and Inhibition

• Negative PrimingNegative Priming

Green

Red

Black

Orange

Blue

GreenPositive Priming

Negative Priming

Attention and Inhibition Attention and Inhibition (and (and alcohol)alcohol)

• Alcohol selectively impairs negative Alcohol selectively impairs negative priming priming BUTBUT has no effect on positive has no effect on positive priming priming (Fillmore, Dixon & Schweizer, 2000a, 2000b).(Fillmore, Dixon & Schweizer, 2000a, 2000b).

• Alcohol impairs the inhibitory gating Alcohol impairs the inhibitory gating processes that serve as mechanisms of processes that serve as mechanisms of selective attention.selective attention.

• Under the drug selective attention more Under the drug selective attention more susceptible to interference from irrelevant susceptible to interference from irrelevant sources.sources.

Present ResearchPresent Research

• Two tasksTwo tasks• Both measure an inhibitory Both measure an inhibitory

mechanism of visual attention.mechanism of visual attention.• Reductionistic ApproachReductionistic Approach

•Need to understand how drugs impair the Need to understand how drugs impair the components of cognition that higher components of cognition that higher processes (i.e., WM, attention) depend on.processes (i.e., WM, attention) depend on.

•Driving is a very complex behavior.Driving is a very complex behavior.•Medication development.Medication development.

Alcohol and Inhibition of Alcohol and Inhibition of Return Return

Posner & Cohen, Posner & Cohen, 19841984

Inhibition of ReturnInhibition of Return

• Makes visual search more efficientMakes visual search more efficient (Klein & MacInnes, 1999).(Klein & MacInnes, 1999).

• Automatic.Automatic.• Present at birthPresent at birth ((Clohessy, et al., 1991)..

• Maximal IOR at 350 – 650 msMaximal IOR at 350 – 650 ms (Klein, 2000).(Klein, 2000).

• Lasts upwards of 2.5 secondsLasts upwards of 2.5 seconds (Samuel & Kat, 2003).(Samuel & Kat, 2003).

• Flexible: location vs. object basedFlexible: location vs. object based (Jordan & Tipper, 1998).(Jordan & Tipper, 1998).

• Involvement of the frontal eye fieldsInvolvement of the frontal eye fields (Ro, Farne, & Chang, (Ro, Farne, & Chang, 2003).2003).

• Functions in all modalitiesFunctions in all modalities (Spence, Nichols, & Gillespie, 1998).(Spence, Nichols, & Gillespie, 1998).

• Sensitive to inhibitory deficits in ADHD and Sensitive to inhibitory deficits in ADHD and schizophreniaschizophrenia (Li, Chang, & Lin, 2003; Larrison, Briand, & Sereno, 2002).(Li, Chang, & Lin, 2003; Larrison, Briand, & Sereno, 2002).

MethodsMethods

• Subjects: 10 healthy undergraduates.Subjects: 10 healthy undergraduates.• Drinking habits: no gender effects, report drinking 4-5 Drinking habits: no gender effects, report drinking 4-5

standard drinks per occasion and 1.5 – 2.5 times a week.standard drinks per occasion and 1.5 – 2.5 times a week.

• Procedure:Procedure:• Phone ScreenPhone Screen

– Answer questionnairesAnswer questionnaires

• FamiliarizationFamiliarization– More questionnairesMore questionnaires– Practice taskPractice task

• 2 alcohol test sessions, 0.65 g/kg and 0.0 g/kg (placebo).2 alcohol test sessions, 0.65 g/kg and 0.0 g/kg (placebo).– DrinkDrink– Perform testPerform test

MethodsMethods

• (2) Test Sessions (2) Test Sessions •Provide urine sampleProvide urine sample

•Pre-session checksPre-session checks

•Receive beverage (0.0 or 0.65 g/kg of pure Receive beverage (0.0 or 0.65 g/kg of pure alc)alc)

•Wait 30 min.Wait 30 min.

•Perform TaskPerform Task

•Wait for BAC to fall (< 0.04)Wait for BAC to fall (< 0.04)

•Paid and released back into the wildPaid and released back into the wild

IOR LayoutIOR Layout

500 ms500 ms

++

IOR LayoutIOR Layout

20 ms20 ms

++

IOR layoutIOR layout

10 ms10 ms

++


20 ms20 ms

++


Target presented 450, 900 or 1200 ms Target presented 450, 900 or 1200 ms later and lasts 1000 ms.later and lasts 1000 ms.

++

Alcohol and IORAlcohol and IOR

• Hypothesis: Based on previous studies Hypothesis: Based on previous studies showing alcohol selectively impairs inhibitory showing alcohol selectively impairs inhibitory mechanisms of attention, we predicted the mechanisms of attention, we predicted the drug would also disrupt proper IOR drug would also disrupt proper IOR functioning.functioning.

• In other words…under alcohol we expect to In other words…under alcohol we expect to see the RT required to detect the target see the RT required to detect the target decrease when cues and targets presented in decrease when cues and targets presented in same location.same location.

IOR Task BreakdownIOR Task Breakdown

• During a Test….During a Test….•300 trials.300 trials.

•20% are catch trials (reduce anticipatory 20% are catch trials (reduce anticipatory responding).responding).

•The remaining 240 trials are split between The remaining 240 trials are split between control and IOR trials.control and IOR trials.

•Each SOA presented equal number of times.Each SOA presented equal number of times.

•Target appears an equal number of times at Target appears an equal number of times at right and left locations.right and left locations.

Alcohol and IOR: ResultsAlcohol and IOR: Results

900 1200

250

300

350

400

0.0 g/kg 0.65 g/kg

SOA (ms)

1200450450 900

275

325

375

Same Cue-Target Condition

Control Condition

Taken from Abroms and Fillmore, Taken from Abroms and Fillmore, 20042004

Alcohol and IOR: ResultsAlcohol and IOR: Results

• Alcohol reduced the duration of IOR.Alcohol reduced the duration of IOR.

• Reduced duration means attention allowed Reduced duration means attention allowed to return to previously scanned area to return to previously scanned area earlier, increasing redundant information earlier, increasing redundant information extraction.extraction.

• Suggests the drug reduces the efficiency Suggests the drug reduces the efficiency with which information is extracted from with which information is extracted from the visual environment.the visual environment.

IOR and Stimulant AbuseIOR and Stimulant Abuse

ConclusionsConclusions

• Evidence is accumulating that shows Evidence is accumulating that shows alcohol disrupts the normal functioning alcohol disrupts the normal functioning of inhibitory mechanisms important for of inhibitory mechanisms important for efficient attention allocation.efficient attention allocation.

• However, a more accurate assessment However, a more accurate assessment of drug effects on visual attention could of drug effects on visual attention could be gained by looking directly at eye be gained by looking directly at eye movements.movements.

Attention and Eye Attention and Eye MovementsMovements

• Why use eye movements as an index Why use eye movements as an index of attention shifts?of attention shifts?

•Both serve same function.Both serve same function.•Better understanding of the circuitry Better understanding of the circuitry

involved.involved.•Attention shift precedes eye movement.Attention shift precedes eye movement.•Are dissociable but rare.Are dissociable but rare.(Hyona, Radach & Deubel, 2003)(Hyona, Radach & Deubel, 2003)

Conclusion: Eye movements provide a more Conclusion: Eye movements provide a more valid assessment than manual responses.valid assessment than manual responses.

Current Eye Movement/Alcohol Current Eye Movement/Alcohol ResearchResearch

• Very little has been done.Very little has been done.• Reliably found that alcohol slows Reliably found that alcohol slows

saccade initiation and speed saccade initiation and speed (i.e., Blekher et al., (i.e., Blekher et al.,

2002; Vassallo & Abel, 2002)2002; Vassallo & Abel, 2002)..• Effects on saccade accuracy Effects on saccade accuracy

equivocal.equivocal.• Investigations of alcohols effect on the Investigations of alcohols effect on the

ability to inhibit eye movements use ability to inhibit eye movements use the anti saccade task.the anti saccade task.

Anti Saccade TaskAnti Saccade Task

• Participants instructed to make a Participants instructed to make a speeded saccade in direction speeded saccade in direction opposite but equal target opposite but equal target (Hallet, 1978)(Hallet, 1978)..

++

Anti Saccade Task and Anti Saccade Task and AlcoholAlcohol

• Reliably found that alcohol improves Reliably found that alcohol improves anti saccade performance.anti saccade performance.

•Under alcohol fewer incorrect pro saccades Under alcohol fewer incorrect pro saccades are made are made (e.g., Kahn et al. 2003)(e.g., Kahn et al. 2003)..

• Also, reliably found alcohol slows the Also, reliably found alcohol slows the speed of the saccade.speed of the saccade.

WHAT!?!WHAT!?!

• Anti saccade results are at odds with Anti saccade results are at odds with both the behavioral literature and both the behavioral literature and studies using other tasks that studies using other tasks that measure inhibitory attentional measure inhibitory attentional mechanisms.mechanisms.

• Could anti saccade results be due to Could anti saccade results be due to a speed vs accuracy trade-off?a speed vs accuracy trade-off?

New TaskNew Task

• Needed: Needed: •A task with simpler response because A task with simpler response because

alcohol’s effect on RT shown to be alcohol’s effect on RT shown to be proportional to task complexity proportional to task complexity (Maylor et al., (Maylor et al.,

1992)1992)..

•A task that actually requires the complete A task that actually requires the complete suppression of all eye movements as it has suppression of all eye movements as it has been shown the availability of an alternate been shown the availability of an alternate response ameliorates alcohol’s effect on response ameliorates alcohol’s effect on behavioral control behavioral control (Abroms, Fillmore & Marczinski, 2003)(Abroms, Fillmore & Marczinski, 2003)..

The Delayed Ocular Return The Delayed Ocular Return Task (DORT) Task (DORT) Ross et al., 2000Ross et al., 2000

• Requires a simple saccade be made to Requires a simple saccade be made to target location.target location.

• Must inhibit reflexive saccade.Must inhibit reflexive saccade.• Saccade must be inhibited until go signal Saccade must be inhibited until go signal

is given.is given.• Also provides RT and visuospatial WM measures.Also provides RT and visuospatial WM measures.

• DORT is sensitive to inhibitory deficit in DORT is sensitive to inhibitory deficit in ADHD and Schizophrenia ADHD and Schizophrenia (Ross et al., 2000)(Ross et al., 2000)..

• Controlled process.Controlled process.

DORT LayoutDORT Layout

1500 ms1500 ms

++


100 ms100 ms

++


800, 1000 or 1200 ms800, 1000 or 1200 ms

++


1000 ms1000 ms


Next fixation appears at correct Next fixation appears at correct saccade location.saccade location.

++

MethodsMethods

• Criterion MeasuresCriterion Measures•Saccades classified as primary or secondary.Saccades classified as primary or secondary.

•Primary saccades classified as premature, Primary saccades classified as premature, valid or late.valid or late.

•Valid primary saccades measured for Valid primary saccades measured for accuracy and speed.accuracy and speed.

DORT HypothesisDORT Hypothesis

• We predicted that alcohol would We predicted that alcohol would decrease control over eye movements. decrease control over eye movements. Specifically we expected an increase in Specifically we expected an increase in the number of premature saccades. the number of premature saccades.

• We hoped there would be no effect on We hoped there would be no effect on RT.RT.

• No predictions were made concerning No predictions were made concerning saccade accuracy.saccade accuracy.

MethodsMethods

• Apparatus:Apparatus:•DORTDORT performed on a PC computer. performed on a PC computer.

•5 target locations, separated by 5.62 degrees.5 target locations, separated by 5.62 degrees.

•Test of 96 trials presented in 2 blocks of 48.Test of 96 trials presented in 2 blocks of 48.

•Presented each angle, in each direction an Presented each angle, in each direction an equal number of times.equal number of times.

•1 minute break between blocks.1 minute break between blocks.

•7 minutes total run time.7 minutes total run time.

MethodsMethods

• Apparatus (continued):Apparatus (continued):• Eye trackerEye tracker is accurate to 0.5 of a degree of visual angle

and has a resolution of 0.5 of a degree. • Locations were sampled at 60 Hz and given an X/Y

coordinate. • Coordinates were used to define fixations and saccades. • To start a fixation the program looked for a period of at

least 100 ms in which the line of gaze had a standard deviation of less than 0.5 degrees of visual angle.

• To end the fixation the program looked for a period of at least 50 ms in which the gaze position was at least 1 degree of visual angle away from the initial fixation position.

• The final fixation position was the average of all data sampled between the beginning and end of the fixation.

• Both saccade duration and visual angle moved were calculated using fixation locations and durations.

ResultsResults

Alcohol

Placebo

Baseline Post BeverageAdministration

1

2

3

4

5

6

7

0

ResultsResults

• No effect of alcohol on number of valid or No effect of alcohol on number of valid or late saccades.late saccades.

• No effect of alcohol on accuracy or RT of No effect of alcohol on accuracy or RT of saccades.saccades.

• 377.6 ms under placebo and 377.7 under alcohol.377.6 ms under placebo and 377.7 under alcohol.

• Interestingly, those with worse accuracy scores were Interestingly, those with worse accuracy scores were disrupted to a greater degree by alcohol. disrupted to a greater degree by alcohol.

ConclusionConclusion

• Alcohol impairs the ability to inhibit Alcohol impairs the ability to inhibit reflexive eye movements.reflexive eye movements.

• Impaired intentional control of eye Impaired intentional control of eye movements under alcohol would suggest the movements under alcohol would suggest the drug makes visual attention more reflexive.drug makes visual attention more reflexive.

•Attention more likely to be captured by Attention more likely to be captured by stimuli not pertinent to current goals.stimuli not pertinent to current goals.

• Inability to “not look” would impact Inability to “not look” would impact performance of a wide range of behaviors.performance of a wide range of behaviors.

General ConclusionGeneral Conclusion

• Alcohol known to slow information processing Alcohol known to slow information processing ((Carpenter, 1962)..

• Reductionistic approach Reductionistic approach (e.g., Barkley, 1997; McClelland & Rumelhart, 1981). • Both studies highlight mechanisms that could Both studies highlight mechanisms that could

account for general impairment under the drug. account for general impairment under the drug. • Under alcohol …..Under alcohol …..

• Visual search less efficient (IOR).Visual search less efficient (IOR).• Visual attention more reflexive (DORT).Visual attention more reflexive (DORT).

• By increasing our understanding of alcohol’s effect By increasing our understanding of alcohol’s effect on these basic mechanisms of attention we begin on these basic mechanisms of attention we begin to understand why drinking would increase risk of to understand why drinking would increase risk of accidents. accidents.

AcknowledgmentsAcknowledgments

• Dr. FillmoreDr. Fillmore

• Dr. GottlobDr. Gottlob

• Emily HarrisonEmily Harrison

• Mike HansbroughMike Hansbrough

• Jaime BlackburnJaime Blackburn

• Angela BowmanAngela Bowman

• Robert PratherRobert Prather

• Christine StilzChristine Stilz

Supported by NIAAA R01 Supported by NIAAA R01 AA12895AA12895

Saccadic Inhibition (S.I.)Saccadic Inhibition (S.I.)

• Refers to the finding that that saccades Refers to the finding that that saccades are slowed if distraction presented are slowed if distraction presented (Reingold & (Reingold & Stampe, 2002, 2003).Stampe, 2002, 2003).

• Automatic process.Automatic process.

• Slowing due to competition between peaks Slowing due to competition between peaks of activation within the superior colliculus. of activation within the superior colliculus. In the lab…In the lab…

• One peak due to task instructions (top-down)One peak due to task instructions (top-down)

• Other peak due to distraction (bottom-up) Other peak due to distraction (bottom-up) Walker & Doyle, 2003Walker & Doyle, 2003

S.I.S.I.

• The slowing of saccade allows for change in The slowing of saccade allows for change in saccade trajectory to occur.saccade trajectory to occur.

• Increases the flexibility with which attention Increases the flexibility with which attention can be allocated to spatial locations.can be allocated to spatial locations.

• Maximum inhibition occurs 100 ms prior to Maximum inhibition occurs 100 ms prior to eye movement eye movement (Reingold & Stampe, 2003).(Reingold & Stampe, 2003).

• Hypothesized alcohol would disrupt S.I. Hypothesized alcohol would disrupt S.I. reducing the time cost associated with reducing the time cost associated with visual distractions presented during eye visual distractions presented during eye movements.movements.

S.I. LayoutS.I. Layout

++

500 or 900 500 or 900 msms


++

Target onset remains for rest of Target onset remains for rest of trial.trial.


++

Distraction trial present brief (33 ms) Distraction trial present brief (33 ms) flash 0, 50, 100, 150 & 200 ms after flash 0, 50, 100, 150 & 200 ms after target onset.target onset.


• 80 trial presented in two blocks of 40 80 trial presented in two blocks of 40 separated by 1 minute break.separated by 1 minute break.

• Target presented in 4 possible Target presented in 4 possible locations 20 times each test.locations 20 times each test.

• Equal number of distraction and Equal number of distraction and control trials.control trials.

Preliminary ResultsPreliminary Results

• With ½ the data in not looking so With ½ the data in not looking so great but not looking so bad either.great but not looking so bad either.

• We might possibly be getting an We might possibly be getting an alcohol effect at the 0 & 50 ms SOA.alcohol effect at the 0 & 50 ms SOA.

• To early to tell just yet.To early to tell just yet.• If we do find an effect: would suggest If we do find an effect: would suggest

attention becomes more ballistic and attention becomes more ballistic and less flexible under alcohol.less flexible under alcohol.

alcohol’s effect on inhibitory mechanisms of visual attention by ben abroms

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