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Towards a true neural stance on consciousness by Victor A.F. Lamme (2006)

Towards a true neural stance on consciousness by Victor A.F. Lamme (2006). Group 10: Chi-Hang Lau, Anita Leung, Clarisse Miguel, Elisa Tsan, Alistair Wong COGS 175 Dr. Pineda 03/12/08. Introduction. About: The Basis of Consciousness Behavioral basis Neural basis

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Towards a true neural stance on consciousness by Victor A.F. Lamme (2006)

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  1. Towards a true neural stance on consciousnessby Victor A.F. Lamme (2006) Group 10: Chi-Hang Lau, Anita Leung, Clarisse Miguel, Elisa Tsan, Alistair Wong COGS 175 Dr. Pineda 03/12/08

  2. Introduction • About: The Basis of Consciousness • Behavioral basis • Neural basis • Lamme: Neural basis “on equal footing” as behavioral basis of consciousness ! • Need a more scientific method for study of consciousness

  3. Introduction • Problem of Consciousness debated by philosophers and scientists • Philosopher Rene Descartes: “Cogito, ergo sum” • Neuroscience: finding the “Neural correlate of consciousness” (NCC)

  4. Introduction • example of Split Brain Patients • Cannot report “seeing” object presented on Left Field of Vision • BUT, S’s can still draw object with left hand ! • Doc these S’s have Consciousness?

  5. Introduction • Two Difficulties: 1. What BEHAVIORAL measures 'count' as conscious experience? 2. Conscious experience is usually coupled with COGNITIVE FUNCTIONS ONE NEEDS TO REPORT ONE IS CONSCIOUS • i.e. language ability and Split Brain patients

  6. Introduction • Lamme: Neural basis “on equal footing” as behavioral basis of consciousness ! • Need a more scientific method for study of consciousness

  7. Measuring Conscious Experience • Where do we draw the line between “conscious” and “un-conscious” experience ? • Looking at behavioral measures • Somewhere between “Object Recognition” and “Localization” ? Figure 1 (Lamme, 2006)

  8. Measuring Conscious Experience (cont.) • Problems ! • Difficult to distinguish a definite boundary • Evidence of conscious experience in one study used as evidence against conscious experience in another study Figure 1 (Lamme, 2006)

  9. From neural activation to visual experience • Example of visual experience • “Feedforward sweep” vs. “Recurrent Processing”

  10. Feed Forward Sweep vs. Recurrent Processing • “Feedforward Sweep” • Signal path: Visual stimuli  retina  V1  V2  motor areas • Signal only goes forward (does not go back) Figure 2 (Lamme, 2006)

  11. Feed Forward Sweep vs. Recurrent Processing • “Recurrent Processing” (RP) • Signal path: Visual stimuli  retina  V1  V2 • Information sent to V1, then to V2, • then exchanged between V1 and higher area V2 Figure 2 (Lamme, 2006)

  12. Recurrent Processing • Local RP • Info exchanged between V1 and higher areas V2, V4, and TE • Widespread RP • Info further exchanged with higher Frontal areas Figure 2 (Lamme, 2006)

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

  14. Recurrent Processing • Exchange of information from lower areas of the brain (ex. V1 and V2) with higher areas of the brain (ex. V4, pre-frontal areas) • RP necessary for consciousness • Current view of consciousness !

  15. Table 1: A) Conflating Conscious experience with other cognitive functions Table 1 (Lamme, 2006)

  16. B) Failures of reportability instead of conscious experience? Table 1 (Lamme, 2006)

  17. B) Failures of reportability instead of conscious experience? Table 1 (Lamme, 2006)

  18. B) Failures of reportability instead of conscious experience? Table 1 (Lamme, 2006)

  19. B) Failures of reportability instead of conscious experience? Table 1 (Lamme, 2006)

  20. B) Failures of reportability instead of conscious experience? Table 1 (Lamme, 2006)

  21. B) Failures of reportability instead of conscious experience? Table 1 (Lamme, 2006)

  22. B) Failures of reportability instead of conscious experience? Table 1 (Lamme, 2006)

  23. Outstanding Questions • What aspect of recurrent processing is necessary for conscious experience? • Activation of high-level neurons • Experiment: Interrupt feedback signals to V1 (with TMS), while recording from face-selective IT cells • Why would recurrent processing create conscious experience? • Difficult to answer, try looking at: • NMDA receptors and theoretical significance of RP • Implications for speed-reading, eidetic memory, and recall under hypnosis

  24. Recurrent processing sufficient for consciousness? • Super et al. • Recorded monkey’s V1, and showed that recurrent interactions are needed for the monkey to report the existence of texture defined figures. • However, after raising number of catch trials, recurrent signals are present when monkey fails to report a figure percept. Figure 3 (Lamme, 2006)

  25. Recurrent processes during inattentional blindness • Results from a modified experiment originally done by Scholte et al. Figure 3 (Lamme, 2006)

  26. Figure 3 (Lamme, 2006)

  27. Figure 3 (Lamme, 2006)

  28. Figure 3 (Lamme, 2006)

  29. Inattentional blindness = absence of conscious experience? • Perhaps subjects only store in memory stimuli that held their attention. • Episodic memory is considered as a measure of conscious experience. • The subject might have just “forgotten” about the stimulus after its presentation. • Experiments on change blindness show that unattended stimuli are still represented in the mind in a quick instance.

  30. Views • Take subject’s reports at face value • RP is insufficient for conscious experience • Consciousness is made up of attention, working memory, and language • Conscious experience must be viewed separately from other cognitive functions • But how to verify conscious experience without examining cognitive functions? • Global workspace theory of consciousness • Preconscious - “visible yet not seen”

  31. "Taking the neuroscience argument seriously" • Is there a conscious experience when recurrent processes only occur in single visual areas? • Are conscious experiences dependent on activity in the frontoparietal network, or is it the recurrency?

  32. "Taking the neuroscience argument seriously" • Stimuli that affect the feedforward processes leave no impact; recurrent processing impacting stimuli does. • Limit definition of consciousness specifically to ONLY Recurrent Processing?

  33. "What do we lose, what do we gain..." • Unconscious dichotomy in everyday actions may be better studied. • Sets Consciousness as a layer in human action for easier examination. • Definition conforms to the current data relating to conscious and neural activity • Provides an easier means to measure consciousness in future experimentation.

  34. Discussion

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