NEUROSCIENCE FOR PHILOSOPHERS

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NEUROSCIENCE FOR PHILOSOPHERS
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Golgi stain of neural structure
www.cs.utexas.edu/users/novak/ramon.gif
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Hippocampal neuron expressing monomeric Green
Fluorescent Protein (GFP)
www.greenspine.ca/en/mGFP_neuron2.html
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• The electrical activity of individual neurons
  during the performance of a task can be monitored
  by single unit recordings. Below you can see the
  sequence of action potentials elicited by a
  neuron during a so-called delay task. In this
  type of experiment working memory is tested by
  inserting a delay period in between the stimulus
  presentation and the point in time the animal is
  allowed to execute the conditioned response.
  During this delay interval the animal has to
  maintain a representation of the previously
  presented stimulus in order to be able to execute
  the correct behavioral response. This neuron
  exhibits an enhanced frequency of action
  potentials that spans the whole delay period.
  Neuronal activity patterns like this most likely
  represent a neuronal correlate of working memory.

• Fig.6 Activity of a neuron during a delay task.
• red bar stimulus presentation
• yellow bar delay period
• Upper half (each row is one task)
• vertical bars action potential spikes
• red dots behavior (beak movements)
• Lower half
• black histogram summed activity across tasks
• green line summed activity on nogo trials

http//www.bio.psy.ruhr-uni-bochum.de/?linkresear
ch/fundaments.php
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SYNCHRONOUS BINDING

• conscious binding occurs when neural cells fire
  together
• Two theories
• 1. synchronous neural oscillations (Crick and
  Koch)
• - requires a particular frequency of firing
  (about 40 hz) to bind various areas.
• 2. synchronous patterns of cell assemblies
  (Engel and Singer)
• - requires temporal correlation of neural
  firing to bind various areas.
• synchrony generated through thalamo-cortical
  loops of brain activity

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NEURAL DARWINISM

• 2 levels of consciousness
• 1. PRIMARY CONSCIOUSNESS connects
  short-term memory and perception to form an
  integrated scene
• 2. HIGHER-ORDER CONSCIOUSNESS connects
  language areas with conceptual systems to form a
  sense of self

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GLOBAL WORKSPACE THEORY
Consciousness is an information processor that
functions as an integration and coordination
mechanism.
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Dehaene, Stanislas et al. (1998) Proc. Natl.
Acad. Sci. USA 95, 14529-14534
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HIGHER-ORDER REPRESENTATION
A mental state M is conscious when there is a
higher-order state about M. The function of
consciousness is explained in terms of the
value of having higher-order states.
red flash
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PAIN

• The intensity of felt pain correlates with the
  activity in somatosensory cortex and cingulate
  cortex.

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BLINDSIGHT

• better than chance guesses about stimuli
  presented in the range of a scotoma, or legion
  field

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SCOTOMA
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TWO VISUAL PATHWAYS

• DORSAL where pathway, occipito-parietal
• VENTRAL what pathway, occipito-temporal

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OCCIPITAL CORTEX
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SENSORY SUBSTITUTION

• utilizing tactile or auditory stimuli to provide
  visual information