Section 6

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Section 6 The Brain

• Chapter 16 The neural correlates of
  consciousness
• Chapter 17 The unity of consciousness
• Chapter 18 Damaged brains

All right, brain, you don't like me, and I don't
like you, but let's just get me through this, and
I can get back to killing you with beer!
Presenters David Mimi Monica
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Why Did the Chicken Cross the Road?

• Nietzsche Because if you gaze too long across
  the road, the road gazes also across you.
• Jean-Paul Sartre In order to act in good faith
  and be true to itself, the chicken found it
  necessary to cross the road
• Albert Einstein Whether the chicken crossed the
  road or the road crossed the chicken depends upon
  your frame of reference.
• Darwin It was the logical next step after coming
  down from the trees.
• Buddha If you ask this question, you deny your
  own chicken- nature.
• Donald Hoffman If we assume that the chicken is
  a conscious agent, then the road is an icon in
  the multimodal user interface.

Cogito Ergo Sum
Descartes
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Chapter 16 The neural correlates of consciousness

How can this gray, wrinkly physical lump of stuff
in be the seat of consciousness?
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• One way to tackle this mind-baffling question is
  to look for neural correlates of consciousness
  (NCC).
• Correlations between neural events and conscious
  experiences DOES NOT imply causality.
• When a correlation between two events, A and B,
  is observed, there are 3 ways to interpret this
  phenomenon.
• 1. A might have caused B
• Neural events cause conscious experience
• 2. B might have caused A
• Conscious experience cause neural events
• 3. Third variable C gives rise to both A B
• X factor cause conscious experience neural
  events.

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Lets consider the unconscious state.

• Prior to surgery, a patient undergoes anesthesia,
  going from a conscious state to an unconscious
  state.
• What is biological mechanism behind this effect?
• Hans Flohr (German neuroscientist) observes that
  the normal functioning NMDA synapse is necessary
  for consciousness.
• Anesthetics abolish consciousness by interfering
  with the functioning of NMDA receptors.
• Conclusion The NCC is the functioning NMDA
  synapses and the cell assemblies they support.
• But is it really that straightforward?

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What is the neural correlate of conscious
visual experiences vs. unconscious vision ?
So far we can locate no single region in which
the neural activity corresponds exactly to the
vivid picture of the world we see in front of our
eyes. Francis Crick
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Are aspects of the visual system competing for
consciousness?

• Binocular rivalry different images are presented
  to the two eyes.
• First experiment were conducted on macaque
  monkeys.
• Procedure Monkeys are shown different display to
  each eye, horizontal grating to one, vertical
  grating to the other.
• Result Some cells in early visual cortex (V1)
  responds to vertical stripes, some responds to
  horizontal stripes. Their behavior did not change
  when the monkey's perception changed. But the
  behavior of these cells did change in the
  inferior temporal cortex (IT), to match what the
  monkey reported seeing.

WHAT DOES THIS MEAN?
THE NCC lies in IT? Can we really assume that
monkey's consciousness human consciousness?
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Phantom Limb Phenomenon

• After losing an arm or leg, 90 of patients
  experience a phantom limb.
• Patients feel pain in their phantom limbs from
  time to time.
• Some report a touch on the face can sometimes
  felt as a touch on the phantom hand.
• What gives rise to this experience?
• The somatosensory cortex map of the body shows
  the sensory input of the face as being
  represented next to the hand.
• If the hand is missing, the sensory input of the
  face will start to invade the hand area.

The Little Man What we would look like if our
body parts are proportional to our sensory input.
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Chapter 17 The unity of consciousness

• Why do we seem to have only one consciousness?
• Eccles dualism The mind plays an active role in
  selecting, reading out and integrating neural
  activity, molding it into a unified whole
  according to its desire or interest.
• A far more constructive approach is to try to
  find out how the brain carries out the
  integrating and unifying functions.
• Or, reject the idea that consciousness really is
  unified at all. Perhaps, on closer inspection, we
  might find that the apparent unity is illusory.
  In this case, the task is to explain how we can
  possibly be so deluded.

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The Binding Problem

• As the coin flips, what keeps the color,form,
  movements and other attributes of the coin
  together?
• In V1, there are many retinotopic maps. That is,
  the organization of cells reflects the layout of
  the retina.
• GWT relates consciousness to working memory.
• There is evidence that attention is required for
  binding.
• However, binding at attention are probably not
  the same thing because some things requiring
  binding are carried out unconsciously catching
  the coin by way of the visuomotor system.

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Binding by synchrony

• The thalamus controls attention by selecting the
  features to be bound together by synchronization
  of firing. (Crick)
• Andreas Engel, Wolf Singer, and colleagues say,
  Neurons forming part of one represented object
  fire together, and they fire out of synchrony
  with neurons representing other objects at the
  same time.
• Synchronization is necessary but not sufficient
  for consciousness. For consciousness, information
  must also enter short-term memory.

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Unity as illusion

• Singleness of action is a vital requirement if
  motor responses were not unified, an animal
  could quite literally tear itself apart!
• Some people reject the idea that consciousness
  is unified at all. Like Dennet's multiple drafts,
  by paying attention to some thing the appearance
  of a unified self having a unified experience is
  created. As soon as attention lapses, the unity
  falls apart and things carry on as normal.

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Doh! what about multiple consciousnesses?

• The unification that comes with
  self-consciousness is an exception that is only
  possible through language.

Semir Zeki (neuroscientist)
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Reentry and the Dynamic Core

• Think of how many people you have seen in your
  lifetime.
• Think of how many paintings youve seen.
• This is a vast amount of information, and you can
  easily discriminate between all these states.
• Consciousness is highly informative is it not?
• There are two types of consciousness (Edelman
  Tononi).
• Primary consciousness many animals have which
  allows for the construction of a scene, the
  maintenance of short-term memory and hence a
  remembered present.
• Higher order consciousness emerged later in
  evolution, depends on reentrant connections
  between language and conceptual systems.

CONSCIOUSNESS OF CONSCIOUSNESS
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Synesthesia Superunity

• Synesthesia confounds the notion that conscious
  experiences are unified.
• To a person who possesses this ability, their
  senses of touch, sight, sound are enmeshed.
• Written letters or numbers are seen as colored,
  but people can hear shapes, see touches or even
  have colored orgasms (woah!).

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• Chapter 18 Damaged Brains

What do you mean I have hemifield neglect?
What is like to blind but believe that you can
see? What is like to be paralyzed but convinced
that you can move? What is like not to notice
that you dont dont notice half of the world?
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Amnesia

• Korsakoff most common form of amnesia, caused by
  the toxic effects of alcohol.
• Retrograde a loss of long-term memory that
  stretches back into the past.
• Classical conditioning remains unimpaired and
  procedure learning remains intact.
• Are amnesiacs conscious?

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Neglect

• Anosagnosia patients are paralyzed but convince
  themselves that they can move.
• Antons syndrome patients are blind but convince
  themselves that they can see.
• Hemifield neglect occurs in right brain damage,
  so patients neglect their left visual field.

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Blindsight

• Blindsight is a condition in which a person
  claims that he or she cannot see a certain area
  of their visual field, but when asked to make a
  guess, that person is right 90-95 of the time
• A person with blindsight could detect a slow or
  fast-moving stimuli, but was only aware of the
  fast ones.

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• Wisdom tells me I am nothing. Love tells me I
  am everything. And between the two, my life
  flows.
• Nisargadatta Maharaj