Week 2 neural basis of consciousness: introduction to the research methods tsuchiya
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12-week lecture series on "the neural basis of consciousness" by Prof Nao Tsuchiya. Given to 3rd year undergraduate level. No prerequisites. Contents: 1) How can we characterize our phenomenology - Introduction to psychophysical methods 2) How can we measure neural activity in the brain? - What is the source of the neural activity?
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Week 2 neural basis of consciousness: introduction to the research methods tsuchiya
- 1. Week 2 Neural basis of consciousness: Introduction to the research methods Prof Nao Tsuchiya Twitter: @conscious_tlab Email: naotsugu.tsuchiya@monash.edu Facebook: Naotsugu Tsuchiya
- 2. Recap of Wk 1 Golden circle - Why - How - What Why, how and what of consciousness research NCC, the Hard problem, Integrated information theory Phenomenology-Experimental Data-Theory A bit of basics: anatomy, neurons
- 3. Learning Objectives How can we characterize our phenomenology Introduction to psychophysical methods How can we measure neural activity in the brain? What is the source of the neural activity? Chapter 2 QFC
- 4. How can we characterize phenomenology? 1. Introspect your own phenomenology 2. Report on your introspection with various methods a. Verbal reports b. Written reports c. Button presses d. Other voluntary behavioral measures (e.g., eye movements, hand adjustments, pointing, …) e. Experiential sampling Intro to psychophysics
- 5. How can we characterize phenomenology? Intro to psychophysics Introspection Reports Pros Cons
- 6. How can we characterize phenomenology? Intro to psychophysics Introspection Reports Pros Can approach conscious experience most directly Cons Introspection itself can alter experience. Unclear whether we can do science on it
- 7. How can we characterize phenomenology? Intro to psychophysics Introspection Reports Pros Can approach conscious experience most directly Easy to quantify Can do science rigorously Cons Introspection itself can alter experience. Unclear whether we can do science on it Cannot exhaust experience. Lead to a wrong attitude
- 8. How can we characterize phenomenology? Intro to psychophysics
- 9. How can we characterize phenomenology? Upon seeing the following image, What are your introspection? What can you report?
- 12. How can we characterize phenomenology? Upon seeing the following image, What are your introspection? What can you report? Repeat the image and think about this again. What’s the role of expectation? Attention? Eye position?
- 13. How can we characterize phenomenology? Intro to psychophysics Experience vs. Reports will be featured in subsequent lectures on No-report paradigms Massive report paradigms
- 14. How can we characterize phenomenology? 1. (Through reasonable interpretation of reports) we can study phenomenology of a. Other adult human beings i. In normal conditions ii. In altered states b. Patients with brain regions c. Children, babies, mammals, … Intro to psychophysics
- 15. Introspection practice Let’s go back to Motion Induced Blindness (MIB) illusion (Bonneh et al 2001 Nature) Link https://www.youtube.com/watch?v=Hfrb94mKCJw https://www.youtube.com/watch?v=EI-bIfC4rVM (Link to ADHD?) Intro to psychophysics
- 16. During your own experience of MIB… What is your criterion of reporting “not seeing”? Are the yellow dots unequivocally either clearly visible vs. clearly invisible? Is there nothing in between? Introspect, observe. Please write any of your observation in Discussion Forum in Moodle! Intro to psychophysics
- 17. During your own experience of MIB… Important methodological (and philosophical) issues: Is your experience all or none? Is consciousness graded? How is your report of “seeing X” and “not seeing X” is related to your “criterion”? MIB is a bit complicated (same stimuli, different conscious experience). So let’s look at a simpler case. Intro to psychophysics
- 18. Simpler phenomenology: backward masking Intro to psychophysics Del Cul et al 2007 PLoS Comp Bio
- 19. Simpler phenomenology: backward masking Intro to psychophysics
- 20. Simpler phenomenology: backward masking https://www.youtube.com/watch?v=Si1nTnZIGI0 SOA : Stimulus Onset Asynchrony Intro to psychophysics
- 21. Simpler phenomenology: backward masking https://www.youtube.com/watch?v=Si1nTnZIGI0 Please try out our experiment : https://mili2nd.co/hdub. Post anything that you observed and thought about in Discussion Forum! Intro to psychophysics
- 23. How can we quantify conscious “seeing”? Introspectively, can you express all of your experiential quality by just “Yes I saw X” vs. “No I did not see”? If not, can we exhaust all experiential quality by adding confidence rating? How should researchers interpret “Yes I saw X with confidence of 1 out of 4” vs. “No I did not see X with confidence 2 out of 4”? Intro to psychophysics
- 24. A rescue: Signal detection theory Are we reporting “not seeing X” Because we actually did not saw it? (issue of sensitivity) Because not really confident to say that seeing X? (Issue of criterion) Important to consider to understand papers on non-conscious / implicit perception, reports from patients and animals. Intro to psychophysics
- 25. An introduction to signal detection theory Intro to psychophysics Stimulus present Stimulus absent Response “I saw it!” Respond “I didn’t see it!”
- 26. An introduction to signal detection theory Intro to psychophysics Stimulus present Stimulus absent Response “I saw it!” Hit Respond “I didn’t see it!” Miss
- 27. An introduction to signal detection theory Intro to psychophysics Stimulus present Stimulus absent Response “I saw it!” Hit False alarm Respond “I didn’t see it!” Miss Correct rejection
- 28. A potential model: signal detection model Intro to psychophysics Stimulus present Stimulus absent
- 29. An introduction to signal detection theory Intro to psychophysics
- 30. An introduction to signal detection theory Intro to psychophysics
- 31. An introduction to signal detection theory Intro to psychophysics
- 32. An introduction to signal detection theory Intro to psychophysics Receiver Operating Characteristics
- 33. An introduction to signal detection theory Intro to psychophysics Receiver Operating Characteristics
- 34. An introduction to signal detection theory Intro to psychophysics Receiver Operating Characteristics
- 35. An introduction to signal detection theory Intro to psychophysics Receiver Operating Characteristics
- 36. An introduction to signal detection theory Intro to psychophysics
- 37. In practice, how can we estimate ROC? Different criterion : Reward, Instruction, Probability of stimulus present vs absent, Usage of confidence rating. This is a bit more involved. Will be explained in later lectures https://www.youtube.com/watch?v=BHkw9_GWPJA&list=TLP QMjgwNzIwMjDcfZszMuGcnA&index=1 https://www.youtube.com/watch?v=UHEiWws8t-g&list=TLPQ MjgwNzIwMjDcfZszMuGcnA&index=2 Intro to psychophysics
- 38. Summary Conscious phenomenology is most directly accessible to introspection. Introspection is a good and necessary start of consciousness research. Translating phenomenology to report is a challenge for consciousness research, but we are making progress. Signal detection theory is a powerful framework to objectively quantify and separate discriminability and criterion.
- 40. Measuring neural activity in the brain is…. ...Very very complicated. In Wk 2, we will glance at the minimal knowledge necessary to understand the papers featured in Tutorials in Week 2. Measuring neural activity
- 41. Measuring neural activity in the brain Measuring neural activity
- 42. Measuring neural activity Cell body Axon Dendrite Synapse Excitatory vs Inhibitory Spike/firing Source of neural activity Cortical layers
- 43. Measuring neural activity Source of neural activity Cortical layers
- 44. Measuring neural activity Source of neural activity
- 45. Electroencephalogram - EEG Measuring neural activity Cortical surface Skull (and other things) Skin
- 46. Electroencephalogram - EEG Measuring neural activity
- 47. Magnetoencephalography - MEG Measuring neural activity
- 48. Intracranial EEG - ElectroCorticoGraphy Measuring neural activity ECoG
- 49. Intracranial EEG - Depth Recording Measuring neural activity
- 50. Comparison of EEG, ECoG, Depth recording Measuring neural activity Buzsaki et al 2012 Nat Rev neuro
- 51. Local field potentials (LFP) & neural activity Measuring neural activityBuzsaki et al 2012 Nat Rev neuro
- 52. EEG, LFP and single unit recording Measuring neural activity Single unit recording (~action potential, spikes, firing, …)
- 53. LFP and single unit recording Measuring neural activity
- 54. functional Magnetic Resonance Imaging fMRI Blood Oxygenation-Level Dependent (BOLD) signal --- relationship between BOLD, synaptic inputs, spiking output are highly complex Measuring neural activity
- 55. Owen et al 2006 Science Measuring neural activity
- 56. BOLD, LFP (synaptic inputs), Spikes Measuring neural activityLogothetis et al 2001 Nature Stimulus present Time (s)
- 57. BOLD, LFP (synaptic inputs), Spikes Measuring neural activityLogothetis et al 2001 Nature Stimulus present Time (s)
- 58. Summary Neural activity can be measured as EEG, MEG, ECoG, LFP. All of these are electrical summation of a population of neural activity (single unit, spiking, firing) with some filtering / smoothing / blurring due to the tissue properties. fMRI is non-invasive, but highly complex. Most likely reflects inputs to the area than outputs from the area. Measuring neural activity
- 59. Putting everything together Measuring neural activity Sejnowski et al 2014 Nat Neuro
- 60. Putting everything together Measuring neural activity Sejnowski et al 2014 Nat Neuro