Week 6 neural basis of consciousness neural correlates of consciousness
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The document discusses the neural basis of consciousness, focusing on the neural correlates of consciousness (NCC) and the role of V1 in conscious vision. It details empirical research on color vision, blindsight, and the properties of neurons in higher visual areas, while highlighting the ongoing debate about V1's role as an NCC. The learning objectives include understanding the evidence for and against V1 as an NCC and examining the properties of visual cortex areas beyond V1.
Week 6 neural basis of consciousness neural correlates of consciousness
- 1. Week 6 Neural basis of consciousness: Neural Correlates of Consciousness Prof Nao Tsuchiya Twitter: @conscious_tlab Email: naotsugu.tsuchiya@monash.edu Facebook: Naotsugu Tsuchiya
- 2. Recap of Wk 5 Argument in support for color vision at the periphery: Brief presentation (no eye movement) still induces vivid color sensation. Neurons at the far eccentricity have bigger RFs. This convergence effect accumulates over the hierarchy. Uniform colored surfaces can be the optimal stimulus for such RFs.
- 3. Recap of Wk 5 Arguments against for color vision at the periphery: Cone “density” degrades rapidly off the fovea. In V1, the fovea is over represented at the expense of the periphery. This cortical magnification implies poor vision (not only for color) at the periphery.
- 4. Recap of Wk 5 Neural mechanisms underlying blindsight ~90% of visual input from the retina goes through LGN to V1 ~10% goes through superior colliculus and pulvinar to the cortex The latter can mediate eye movements and localization in a nonconscious manner in blindsight
- 5. Recap of Wk 5 Important concepts/features of neurons in the visual system. RF and visual hierarchy Complexication of RF properties Bigger size of RF (but, temporal latency may not respect hierarchy) Columnar organization & layer structure Multiple visual pathways
- 6. In Wk 6, We will address the questions of: What is the link between neurons and phenomenology? What is the role of V1 for conscious vision? What are the properties of the visual cortex beyond V1?
- 7. Learning Objectives To be able to answer the following questions: ● What are the neural correlates of consciousness (NCC)? ● What are positive and negative evidence for V1 as the NCC? ● What are the properties of neurons in higher visual areas? QFC Chapter 5, 6, 7, 8 (Optional: Frith 1999)
- 8. In Week 5, we encountered … ... the following fundamental questions: ● Why do we not see images upside down? ● Why do we not see images in a distorted way? ● What is the relationship between the outside world, our experience and neurons in the brain? What is the NCC?
- 9. Are we stuck with these questions? 1990~: An empirical scientific research program Search for the neural correlates of consciousness “It seems probable, however, that at any one moment some active neuronal processes correlate with consciousness, while others do not. What are the differences between them? … Where in the brain are the neural correlates of consciousness?” What is the NCC?
- 10. The NCC QFC Glossary: “The minimal set of neuronal mechanisms or events jointly sufficient for a specific conscious percept or experience (Figure 1.1 and Chapter 5). This is what this book is about” What is the NCC?
- 11. Further refinement of the NCC Full neural correlates of consciousness: The neural substrate supporting experience in general, irrespective of its specific content. Content-specific neural correlates of consciousness: The neural substrate supporting a particular content of experience (for example, faces) whether seen, dreamt or imagined. Koch 2016 Nat Rev Neuro What is the NCC?
- 12. How can we find the NCC? -> Final project Frith 1999 Trends Cogn Sci What is the NCC? Neural Correlates of Sensory stimulation Neural Correlates of Behaviors Fix two while varying only one. Fix one and examine the relations of the two.
- 13. Frith 1999 Trends Cogn Sci What is the NCC?
- 14. Frith 1999 Trends Cogn Sci What is the NCC?
- 15. Frith 1999 Trends Cogn Sci What is the NCC?
- 16. Frith 1999 Trends Cogn Sci What is the NCC?
- 17. Frith 1999 Trends Cogn Sci What is the NCC?
- 18. Frith 1999 Trends Cogn Sci What is the NCC?
- 19. What is the NCC? Summary Searching the NCC is an empirical research program that has made a huge advance since 1990. There are many empirical approaches, some of which can be great inspiration for your final research proposal (Assessment 4 & 5)!
- 21. Where is the NCC? Based on blindsight discussion, it seems the first candidate area for the NCC is V1. Blindsight : loss of phenomenology due to V1 damage Let’s see the evidence for and against it! Does V1 qualify as the NCC?
- 22. A psychologists’ “microelectrode”: Adaptation QFC Glossary: Aftereffect: Prolonged exposure to a stimulus attribute causes a short lived deficit in the ability to detect that attribute (as in the orientation-dependent aftereffect; Section 6.2). In some cases, the opposite attribute is seen, as in the motion aftereffect where the observer sees upward motion after being habituated to downward motion (also known as the waterfall illusion; Section 8.3) or in color afterimages. Aftereffects are thought to be caused by a recalibration or adaptation of the underlying neurons. Does V1 qualify as the NCC?
- 23. A psychologists’ “microelectrode”: Adaptation Aftereffects are thought to be caused by a recalibration or adaptation of the underlying neurons. ○ Adaptation can cause vivid alteration of conscious phenomenology without changing the stimulus (>>> fixed NCS with varied NCC) ○ If the adaptation is caused by specific neurons, it can be used to infer WHERE in the brain the adaptation is happening. ○ Adaptation can be combined with independent manipulation of consciousness (or visibility) and “attention”.Does V1 qualify as the NCC?
- 24. + Does V1 qualify as the NCC?
- 25. + Does V1 qualify as the NCC?
- 26. Combination of afterimage, Troxler fading and attentional modulation? https://michaelbach.de/ot/ Lilac Chaser https://michaelbach.de/ot/col-lilacChaser/index.html Does V1 qualify as the NCC?
- 27. + Does V1 qualify as the NCC?
- 28. + Does V1 qualify as the NCC?
- 29. + Does V1 qualify as the NCC?
- 30. + Does V1 qualify as the NCC?
- 31. Orientation-dependent adaptation as a probe Considered to occur in V1 (and beyond). Why? Neurons in the retina and LGN RF do not have selectivity to the line orientation Do we need to consciously see the adaptor during adaptation? Does V1 qualify as the NCC?
- 32. Dissociating “adaptation” from “visibility” with “crowding” Does V1 qualify as the NCC? He 1996 Nature
- 33. He 1996 Nature
- 34. Dissociating “adaptation” from “visibility” with “crowding” Does V1 qualify as the NCC? He 1996 Nature
- 35. Dissociating “adaptation” from “visibility” with “crowding” Does V1 qualify as the NCC? He 1996 Nature
- 36. Dissociating “adaptation” from “visibility” with “crowding” Does V1 qualify as the NCC? Crowded / invisible orientation still evoke strong threshold elevation (= strong adaptation) He 1996 Nature
- 37. Other evidence in favor of V1 as not the NCC Does V1 qualify as the NCC? QFC Ch 6 Dreaming vs V1 (during REM, V1 is suppressed) V1 neurons’ properties do not follow properties of consciousness Eye of origin information is not consciously accessible V1 cells are affected by blinks and eye movements
- 38. Crick & Koch 1995 V1 Hypothesis NCC is not in the V1 V1 has no direct projection to the prefrontal and premotor cortical areas Does V1 qualify as the NCC?
- 39. Summary Crick & Koch’s V1 hypothesis promoted various empirical research since 1995 V1’s involvement for “reported/reportable” percepts are unlikely based on various perceptual and neuronal findings. However, in terms of its involvement for consciousness per se, it is still unclear. What about the other areas beyond V1? Does V1 qualify as the NCC?
- 41. Visual consciousness and visual areas beyond V1 Beyond V1
- 42. Cortical flattening & retinotopy for V1-V4 Beyond V1 https://www.youtu be.com/watch?v= aj-d8PZMXt8
- 43. Neurons in V2 strongly responds to illusory line Beyond V1
- 44. Crowded illusory line also generates adaptation Beyond V1Montaser-Kouhsari 2008 Vision Research
- 45. Crowded illusory line also generates adaptation Beyond V1Montaser-Kouhsari 2008 Vision Research
- 46. … Does nonconscious adaptation requires attention? Beyond V1Montaser-Kouhsari 2008 Vision Research
- 47. Summary Neurons in V2 responds to illusory lines. Illusory lines can generate adaptation even they are not visible. However, this nonconscious adaptation requires attentional amplification. Does this pose a question about “sufficiency” of attention for conscious perception? -> Next week Beyond V1
- 49. Visual motion and Middle Temporal (MT/V5) area (Don’t confuse MT with MTL - Medial Temporal Lobe - containing hippocampus and amygdala) Beyond V1 MT/V5 MTL
- 50. Motion after effects and consciousness Motion aftereffects (Requires visibility & attention) https://michaelbach.de/ot/mot-adapt/index.html Beyond V1
- 51. Adaptation to visible vs. invisible simple and complex motion Beyond V1 Initial 68s adaptation, then top up 2s Kaunitz 2011 J of Vision
- 52. Adaptation to simple and complex motion Simple motion : evokes sizable MAE without consciousness and without attention Beyond V1Kaunitz 2011 J of Vision
- 53. Adaptation to simple and complex motion Visible complex motion evokes MAE. Invisible complex motion evokes very weak MEA. Beyond V1Kaunitz 2011 J of Vision
- 54. fMRI & psychophysics of Motion After Effects Beyond V1Tootell 1995 Nature
- 55. fMRI & psychophysics of Motion After Effects Tootell 1995 Nature Beyond V1
- 56. Phenomenological reports of bilateral MT patients QFC Glossary: Akinetopsia: A specific deficit in the perception of visual motion due to a cortical lesion in and around area MT (Section 8.3). Fiction, but it looks quite compelling https://www.youtube.com/watch?v=B47Js1MtT4w Motion perception deficit in monkey (Newsome 1988 JNS) Beyond V1
- 57. MT neurons responds to motion direction and depth Beyond V1
- 58. Causal relationships between MT neurons’ firing and perceptual decision Beyond V1 https://www.youtube.com/watch? v=7OdCe95IiLw Newsome 1989 NatureBritten 1992 JNsci
- 59. Causal relationships between MT neurons’ firing and perceptual decision Beyond V1Newsome 1989 Nature
- 60. Causal relationships between MT neurons’ firing and perceptual decision Beyond V1 Salzman 1990 Nature
- 61. Summary MT’s causal role for visual motion qualia is strongly implicated by phenomenology, psychophysics, fMRI, lesion, neurophysiology and microstimulation. Bilateral lesion abolishes motion qualia (but not others) Microstimulation causally interfere with the motion judgement. Beyond V1
- 62. Summary Why does MT generate motion qualia? What is special about MT? Input? Output? Biophysics? Local neural circuitry? This is another form of the Hard Problem... Beyond V1