Towards a true neural Towards a true neural stance onstance on

consciousnessby Victor A.F. Lamme (2006)

Group 10: Chi-Hang Lau, Anita Leung, Group 10: Chi-Hang Lau, Anita Leung, Clarisse Miguel, Elisa Tsan, Alistair Clarisse Miguel, Elisa Tsan, Alistair

WongWongCOGS 175COGS 175

Dr. PinedaDr. Pineda03/12/0803/12/08

IntroductionIntroductionAbout: The Basis of ConsciousnessAbout: The Basis of Consciousness

• Behavioral basisBehavioral basis• Neural basisNeural basis

Lamme: Neural basis “on equal Lamme: Neural basis “on equal footing” as behavioral basis of footing” as behavioral basis of consciousness !consciousness !– Need a more scientific method for Need a more scientific method for

study of consciousnessstudy of consciousness

IntroductionIntroductionProblem of Consciousness debated Problem of Consciousness debated by philosophers and scientistsby philosophers and scientists– Philosopher Rene Descartes: “Cogito, ergo sum”Philosopher Rene Descartes: “Cogito, ergo sum”– Neuroscience: finding the “Neural Neuroscience: finding the “Neural

correlate of consciousness” (NCC)correlate of consciousness” (NCC)

IntroductionIntroductionexample of Split Brain Patientsexample of Split Brain Patients– Cannot report “seeing” object Cannot report “seeing” object

presented on Left Field of Visionpresented on Left Field of Vision• BUT, S’s can still draw object with left BUT, S’s can still draw object with left

hand !hand !

Doc these S’s have Doc these S’s have Consciousness?Consciousness?

IntroductionIntroductionTwo Difficulties:Two Difficulties:1. What BEHAVIORAL measures 'count' as 1. What BEHAVIORAL measures 'count' as

conscious experience?conscious experience?

2. Conscious experience is usually 2. Conscious experience is usually coupled with COGNITIVE FUNCTIONS coupled with COGNITIVE FUNCTIONS ONE NEEDS TO REPORT ONE IS ONE NEEDS TO REPORT ONE IS CONSCIOUSCONSCIOUS• i.e. language ability and Split Brain patientsi.e. language ability and Split Brain patients

IntroductionIntroductionLamme: Neural basis “on equal Lamme: Neural basis “on equal footing” as behavioral basis of footing” as behavioral basis of consciousness !consciousness !

Need a more scientific method for Need a more scientific method for study of consciousnessstudy of consciousness

Measuring Conscious Measuring Conscious ExperienceExperience

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Where do we draw the Where do we draw the line between line between “conscious” and “un-“conscious” and “un-conscious” experience ?conscious” experience ?– Looking at behavioral Looking at behavioral

measuresmeasures

Somewhere between Somewhere between “Object Recognition” “Object Recognition” and “Localization” ?and “Localization” ?

Figure 1 (Lamme, 2006)

Measuring Conscious Measuring Conscious Experience Experience (cont.)(cont.)

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Problems !Problems !Difficult to distinguish a Difficult to distinguish a definite boundarydefinite boundary

Evidence of conscious Evidence of conscious experience in one study used experience in one study used as evidence against conscious as evidence against conscious experience in another studyexperience in another study

Figure 1 (Lamme, 2006)

From neural activation to From neural activation to visual experiencevisual experience

Example of visual experienceExample of visual experience

““Feedforward sweep” vs. Feedforward sweep” vs. “Recurrent Processing”“Recurrent Processing”

““Feedforward Sweep”Feedforward Sweep”– Signal path: Visual Signal path: Visual

stimuli stimuli retina retina V1 V1 V2 V2 motor areas motor areas

Signal only goes Signal only goes forward (does not go forward (does not go back)back)

Feed Forward SweepFeed Forward Sweep vs. vs. Recurrent ProcessingRecurrent Processing

Figure 2 (Lamme, 2006)

““Recurrent Processing” Recurrent Processing” (RP)(RP)– Signal path: Visual stimuli Signal path: Visual stimuli

retina retina V1 V1 V2 V2

Information sent to V1, Information sent to V1, then to V2, then to V2, – then exchanged between then exchanged between

V1 and higher area V2V1 and higher area V2

Feed Forward Sweep vs. Feed Forward Sweep vs. Recurrent ProcessingRecurrent Processing

Figure 2 (Lamme, 2006)

Recurrent Processing

Local RPLocal RP– Info exchanged Info exchanged

between V1 and higher between V1 and higher areas V2, V4, and TEareas V2, V4, and TE

Widespread RP Widespread RP – Info further exchanged Info further exchanged

with higher Frontal with higher Frontal areasareas

Figure 2 (Lamme, 2006)

Recurrent Processing

Exchange of information from Exchange of information from lower areas of the brain (ex. V1 lower areas of the brain (ex. V1 and V2) with higher areas of the and V2) with higher areas of the brain (ex. V4, pre-frontal areas)brain (ex. V4, pre-frontal areas)

Recurrent Processing

Exchange of information from Exchange of information from lower areas of the brain (ex. V1 lower areas of the brain (ex. V1 and V2) with higher areas of the and V2) with higher areas of the brain (ex. V4, pre-frontal areas)brain (ex. V4, pre-frontal areas)

RP necessary for consciousnessRP necessary for consciousness– Current view of consciousness !Current view of consciousness !

Table 1: A) Conflating Conscious experience with other cognitive

functions

Table 1 (Lamme, 2006)

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B) Failures of reportability instead of conscious experience?

Table 1 (Lamme, 2006)

B) Failures of reportability instead of conscious experience?

Table 1 (Lamme, 2006)

B) Failures of reportability instead of conscious experience?

Table 1 (Lamme, 2006)

B) Failures of reportability instead of conscious experience?

Table 1 (Lamme, 2006)

B) Failures of reportability instead of conscious experience?

Table 1 (Lamme, 2006)

B) Failures of reportability instead of conscious experience?

Table 1 (Lamme, 2006)

B) Failures of reportability instead of conscious experience?

Table 1 (Lamme, 2006)

Outstanding QuestionsWhat aspect of recurrent processing is What aspect of recurrent processing is necessary for conscious experience?necessary for conscious experience?– Activation of high-level neuronsActivation of high-level neurons

• Experiment: Interrupt feedback signals to V1 (with Experiment: Interrupt feedback signals to V1 (with TMS), while recording from face-selective IT cellsTMS), while recording from face-selective IT cells

Why would recurrent processing create Why would recurrent processing create conscious experience?conscious experience?– Difficult to answer, try looking at:Difficult to answer, try looking at:

• NMDA receptors and theoretical significance of RPNMDA receptors and theoretical significance of RP

Implications for speed-reading, eidetic Implications for speed-reading, eidetic memory, and recall under hypnosismemory, and recall under hypnosis

Recurrent processing sufficient for consciousness?

Super et al.Super et al.– Recorded monkey’s V1, Recorded monkey’s V1,

and showed that and showed that recurrent interactions recurrent interactions are needed for the are needed for the monkey to report the monkey to report the existence of texture existence of texture defined figures.defined figures.

– However, after raising However, after raising number of catch trials, number of catch trials, recurrent signals are recurrent signals are present when monkey present when monkey fails to report a figure fails to report a figure percept.percept. Figure 3 (Lamme, 2006)

Recurrent processes during inattentional

blindness

Results from a Results from a modified modified experiment experiment originally done by originally done by Scholte et al.Scholte et al.

Figure 3 (Lamme, 2006)

Figure 3 (Lamme, 2006)

Figure 3 (Lamme, 2006)

Figure 3 (Lamme, 2006)

Inattentional blindness = absence of conscious experience?

Perhaps subjects only store in memory stimuli Perhaps subjects only store in memory stimuli that held their attention.that held their attention.

Episodic memory is considered as a measure Episodic memory is considered as a measure of conscious experience.of conscious experience.– The subject might have just “forgotten” about the The subject might have just “forgotten” about the

stimulus after its presentation.stimulus after its presentation.

Experiments on change blindness show that Experiments on change blindness show that unattended stimuli are still represented in the unattended stimuli are still represented in the mind in a quick instance.mind in a quick instance.

Views1.1. Take subject’s reports at face valueTake subject’s reports at face value

– RP is insufficient for conscious experienceRP is insufficient for conscious experience– Consciousness is made up of attention, working Consciousness is made up of attention, working

memory, and languagememory, and language

2.2. Conscious experience must be viewed Conscious experience must be viewed separately from other cognitive functionsseparately from other cognitive functions

– But how to verify conscious experience without But how to verify conscious experience without examining cognitive functions?examining cognitive functions?

3.3. Global workspace theory of consciousnessGlobal workspace theory of consciousness– Preconscious - “visible yet not seen”Preconscious - “visible yet not seen”

"Taking the neuroscience argument seriously"

Is there a conscious experience Is there a conscious experience when recurrent processes only when recurrent processes only occur in single visual areas?occur in single visual areas?

Are conscious experiences Are conscious experiences dependent on activity in the dependent on activity in the frontoparietal network, or is it the frontoparietal network, or is it the recurrency?recurrency?

Stimuli that affect the feedforward Stimuli that affect the feedforward processes leave no impact; recurrent processes leave no impact; recurrent processing impacting stimuli does.processing impacting stimuli does.

Limit definition of consciousness Limit definition of consciousness specifically to ONLY Recurrent specifically to ONLY Recurrent Processing? Processing?

"Taking the neuroscience argument seriously"

"What do we lose, what do "What do we lose, what do we gain..."we gain..."

Unconscious dichotomy in everyday actions may be Unconscious dichotomy in everyday actions may be better studied.better studied.

Sets Consciousness as a layer in human action for Sets Consciousness as a layer in human action for easier examination.easier examination.

Definition conforms to the current data relating to Definition conforms to the current data relating to conscious and neural activityconscious and neural activity

Provides an easier means to measure consciousness in Provides an easier means to measure consciousness in future experimentation.future experimentation.

Discussion