12-week lecture series on "the neural basis of consciousness" by Prof Nao Tsuchiya. Given to 3rd year undergraduate level. No prerequisites. Contents: 1) Why are the studies of brain lesioned patients important? 2) What are reported phenomenology by patients? 3) How can we assess / validate their phenomenology? - Behavioral & Neuronal studies of patients

1. Week 3
Neural basis of consciousness:
Overview of important clinical cases
Prof Nao Tsuchiya
Twitter: @conscious_tlab
Email: naotsugu.tsuchiya@monash.edu
Facebook: Naotsugu Tsuchiya

2. Recap of Wk 2
Phenomenology
Introspection & Report
Experience of brief exposures to a natural scene
Signal detection theory

3. Recap of Wk 2
Neurons & neural measures
Basic anatomy (dendrites, axons, action potentials)
EEG, MEG, ECoG, LFP, single unit recording
fMRI
Pros and cons of various measures

4. Measuring neural activity
Sejnowski et al 2014 Nat
Neuro

5. Learning Objectives
To be able to answer the following questions:
Why are the studies of brain lesioned patients important?
What are reported phenomenology by patients?
How can we assess / validate their phenomenology?
Behavioral & Neuronal studies of patients
Chapter 12 QFC

6. Learning the boundary of the knowledge (Assessment 2 & 3)
1. Brain injured patients Pheno
2. Characterizing conscious phenomenologies Pheno
3. Attention and consciousness Pheno + Measure
4. Implicit and unconscious perception Measure
5. Consciousness research in animals Pheno + Measure
6. Intracranial recordings in humans Measure
7. Reorganization of brains and altered consciousness
Pheno + Measure

7. Why are the studies of brain lesioned patients important?
Because it is the most effective and holistic way to
understand what consciousness is, is not and can be.
Data from brain lesioned patients provide strong constraints
on ideas and theories of consciousness.
Many hand-wavy philosophical ideas can be excluded.
Refining “mind-body” problem into “consciousness-brain”.
Why brain injury?

8. Why are the studies of brain lesioned patients important?
Brain lesions also give us clues about the necessity of a
particular brain areas for phenomenology.
One way to get to the causal relationship between
neurons and consciousness.
(Other ways: micro stimulations, drug manipulations, and
(coarse) magnetic stimulation)
Why brain injury?

10. What it is like to be locked-in patients?
Movie: The Diving Bell and the Butterfly (2007)
Trailer https://www.youtube.com/watch?v=TGPhtOMOCcg
Full movie
https://www.sbs.com.au/ondemand/video/1406388291596/th
e-diving-bell-and-the-butterfly
Reports/behaviors of the patients

11. Locked-in syndrome
Reports/behaviors of the patients

12. Critical lesion for
locked-in syndrome
Bruno et al 2015
Neurology of
consciousness
Neural basis of consciousness in patients

13. Locked-in
syndrome
Conscious
control
Brain metabolism
Neural basis of consciousness in patients

14. Neural basis of consciousness in patients
Minimally conscious state
Vegetative state
Locked-in
syndrome
Conscious
control

15. Owen et al
2006 Science
Neural basis of consciousness in patients

16. Monti et al
2011 NEJM
5/54 patients
2/5 no voluntary
behavior
Neural basis of consciousness in patients

17. Reports by patients
Insight 2014 Conscious or not
Around 28:00
Interview of a patient who came out of misdiagnosed coma
https://www.youtube.com/watch?v=_09fxGB8EjQ
Reports/behaviors of the patients

18. Summary
Consequences of brain damage on consciousness are
difficult to imagine.
Movies allow us to virtually experience what it is like to be a
brain-damaged patient.
Conscious experience of a patient can dissociate from
externally observable behaviors.
Brain mechanisms of locked-in and other syndromes are
being studied extensively.

19. Why are the studies of brain lesioned patients important?
Because it is the most effective and holistic way to
understand what consciousness is, is not and can be.
Why brain injury?

20. Can this brain generate consciousness?
Yu et al 2014 Brain
“A new case of complete
primary cerebellar agenesis:
clinical and imaging findings
in a living patient”
Reports/behaviors of the patients

21. “mild mental impairment and medium motor
deficits… complete absence of the
cerebellum…
A 24-year-old female patient was admitted to
hospital complaining of dizziness and the
inability to walk steadily for more than 20 years,
and nausea and vomiting for 1 month...
married with a daughter, and her pregnancy
and delivery were described as uneventful…
4 years old before she could stand unassisted,
and did not begin to walk unassisted until the
age of 7…
Reports/behaviors of the patients

22. … Her speech was not intelligible until 6
years of age and she did not enter
school.
A neurological examination revealed she
could cooperate and fully orientate.
A verbal analysis test revealed her word
comprehension and expression
remained intact and she had no sign of
aphasia…
Evaluation of the sensory system
showed no abnormalities”
Reports/behaviors of the patients

23. The entire cerebellum is irrelevant for
consciousness!
This is not really trivial! (Any theory of consciousness has to
give a reasonable explanation on why this is the case).
To put this fact into a perspective, let’s consider several
numbers and facts.
Why brain injury?

24. What generates consciousness?
A naive (but very popular) idea → Complexity!
Human brain is super complicated. And complexity is all you
need to generate complex conscious experience!
How many neurons are there in the brain?
86,000,000,000 (roughly 1011
) neurons!
Each neuron connected with 1000-10,000 neurons
Neural basis of consciousness in patients

25. Important numbers to think about
- In 2020, there are ~8 billion people.
- Imagine we have 10 times more people on the earth.
- And each person communicates with 1000-10,000 other
people. (How many friends do you have in your
FaceBook, Instagram, Twitter?)
Something like that is happening in your brain!
Neural basis of consciousness in patients

26. And…
Cerebral cortex contains ~15 billion neurons
Cerebellum contains ~60 billion neurons
Why do we not lose consciousness, even if we lose ~80% of
the neurons in the brain???
We need a theoretical and principled explanation.
→ Integrated information theory by Tononi
Herculano-Houzel 2012 PNAS
Neural basis of consciousness in patients

28. Can this brain generate consciousness?
Why brain injury?
Mataro 2001 Arch
Neurol

29. Why brain injury?

30. The prefrontal cortex is responsible for …
Decision making
Impulse control
Judgement
Emotion control
Social interactions
… but is it really relevant and critical for consciousness?
Ongoing debates
Boly et al 2017 J Nsci
Odegaard et al 2017 J Nsci
Why brain injury?

31. Why brain injury?

32. Long-term Effects of Bilateral Frontal Brain Lesion
60 Years After Injury With an Iron Bar
At the age of 21 years, in 1937, he
was forced to escape through a
window and slid down a pipe that
gave way. He fell and he was
impaled, through the head, on the
spike of an iron gate. He remained
there until the bar was cut; he was
conscious, and even helped in the
rescue.”
Reports/behaviors of the patients

33. “His occupations consisted mainly
of simple manual tasks that were
always organized and checked by
others. He required supervision
even in everyday activities. He
was incapable of planning or
remembering his agenda or of
fulfilling his responsibilities and he
had difficulties managing money.”
“The spike (Figure 2) penetrated the left frontal region,
passed through both frontal lobes injuring the left eyeball, and
emerged from the right side.”
Reports/behaviors of the patients

34. “Also noteworthy were his apathy, lack of drive, and problems
with initiating, continuing, and finishing tasks. Restlessness
and impatience were also occasionally reported. Another
noticeable characteristic was his cheerfulness; he would
spend a long time telling the same jokes.”
Bilateral frontal lobe damage does not seem to cause lower
level of consciousness and spares most sensory
consciousness (=contents of consciousness), while
profoundly alter human nature and social interactions.
Then, where does consciousness come from?
Reports/behaviors of the patients

35. Consciousness lost and found
A case of “Blindsight”

36. Behaviors of patients
Video of Helen
https://www.youtube.com/watch?v=rDIsxwQHwt8
Human blindsight patient
https://www.youtube.com/watch?v=GwGmWqX0MnM
Reports/behaviors of the patients

37. de Gelder et al 2008
Curr Bio
Patient TN
Neural basis of consciousness in patients

38. Simple visual test (perimetry) shows…
LeftRight
Assessment and validation of phenomenology
Right
___
Stoerig et al 2002 Cereb Cor

39. Localization task
180 ms
Spatial
2-alternative
forced choice
+ verbal
awareness report
Reports/behaviors of the patients
Stoerig et al 2002 Cereb Cor

40. Absolute blindsight: localization task
Reports/behaviors of the patients
Stoerig et al 2002 Cereb Cor

41. Relative blindsight: localization task
Reports/behaviors of the patients
Stoerig et al 2002 Cereb Cor

42. Can we dissociate not seeing from high criterion?
Receiver Operating Characteristics
Assessment and validation of phenomenology

43. Signal detection task
No I did not
see anything
(35% of trials)
3% contrast
target
Yes I saw it
here
(60% of trials)
[30% 46% or 99%]
contrast target
Yes I saw it here
(5% of trials)
Assessment and validation of phenomenology
Stoerig et al 2002 Cereb Cor

44. The effects of changing stimulus frequency
Assessment and validation of phenomenology
Stoerig et al 2002 Cereb Cor

45. Signal detection task
No I did not
see anything
(20% of trials)
3% contrast
target
Yes I saw it
here
(60% of trials)
[30% 46% or 99%]
contrast target
Yes I saw it here
(20% of trials)
Assessment and validation of phenomenology
Stoerig et al 2002 Cereb Cor

46. The effects of changing stimulus frequency
Assessment and validation of phenomenology
Stoerig et al 2002 Cereb Cor

47. Detection vs Localization
Assessment and validation of phenomenology

48. What does this all mean?
Behavioral observations: these patients and monkeys
navigate through the world by visually (?) recognizing the
objects. A localization task can be performed very well.
Phenomenological reports: Patients complain total loss of
vision. In a signal detection task, patients deny seeing the
target regardless of frequency of targets.
Are they lying? If not, how can we explain these?
Why brain injury?

49. How can we assess / validate their phenomenology?
What can we do?
Combine signal detection with confidence
How blindsight is possible
Deeper dive into the visual system: from eye to V1
Assessment and validation of phenomenology