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Attention, Binding, and Consciousness

1. Perceptual binding, dynamic binding2. Neural Correlates of Consciousness:

Binocular rivalry 3. Attention vs. consciousness4. Binding revisited:

Split-brain, split-consciousness

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Asingleintegrated whole:theintrinsicunity

ofconsciousexperience

WHATUNITYOFCONSCIOUSNESS?

MikeGazzaniga1967

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Communicatingwithasinglehemisphere

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“…let not thy left hand know what thy right hand doeth.”Matthew 6:3

Multitasking:splittingtheattentionalbottleneck

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Inter-hemispheric interference

Serialsearch— inparallel!

SPLIT-BRAIN<700ms

WHOLE-BRAIN~700ms

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Theleft-hemisphereinterpreter

establishesarunning

narrativeand

self-concept

Whydidyoupickthosepictures?“Ohthat’ssimple.Thechickenclawgoeswiththechicken,Andyouneedashoveltocleanoutthechickenshed.

Hemispheric specialization

Leftisbetterat• Speaking, language• Problem solving, planning,

intelligence• Interpretation,

hypothesizing, story-making, confabulation

• Voluntary smiling, top-down attention

Rightisbetterat• Pattern matching• Face recognition• Perceptual grouping/illusory

contours• 3D drawing• Being veridical• Global attention

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Conclusions from split-brain studies

• Although the right hemisphere has very limited verbal abilities, surgically separating the hemispheres appear to result in two independent consciousnesses, one in each hemisphere: split-brain, split consciousness.

• This result does not conflict with the observation or claim that consciousness is an intrinsically unified state.

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Consciousness Conclusions• We seek the NCC—the minimal brain events

sufficient for a conscious percept.

• Conscious awareness may be associated with neural synchrony and/or the firing of small groups of neurons in higher-order sensory areas like IT and STS.

• Ultimately our theory of consciousness should relate it consistently to other phenomena described by science.

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Perceptual decisions and the Diffusion model

1. Area MT and motion perception2. Area LIP and evidence accumulation

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Motiondiscriminationtask

“2AlternativeForcedChoice”

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Motion in pref. direction

Motion in null direction

Motion in pref. direction

Motion in null direction

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Motion in pref. direction

Motion in null direction

Area under curve:For 12.8% correlation…area is almost the whole square.

For 0.8% saturation…area is half of total square.

MTcellscarryinfoaboutvisualmotion:

strongermotion,betterinfo

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MicrostimulationinareaMTshiftsthepsychometriccurve

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1. Area MT and motion perception2. Area LIP and evidence accumulation

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Perceptual decisions and the Diffusion model

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Diffusionmodelofaperceptualdecision

I.e.integratesthedifference betweenevidenceforandagainstchoiceA

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LIPactivityrampsupduringthemotionstimulus

Strongermotion,

fasterrampup

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Probabilityofpredictingthemonkey’schoicebasedonLIPcellfiringalsorampsup

MTleft=solidblackMTright=grayfilledLIP=redline=timeintegralofMTdifference

LIPneuronastemporalintegrator

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2006

JournalclubslidesfromDaniMarti

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Nowmonkey

canrespondanytimeafterthemotionstimulusappears

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Diffusionmodelofaperceptualdecision

I.e.integratesthedifference betweenevidenceforandagainst