Learning-induced synchronization and plasticity of a developing neural network

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Learning-induced synchronization and plasticity
of a developing neural network

• T.-C. Chao and C.-M. Chen
• Physics, NTNU

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A Prototype of the Brain Sea Squirts
The development of the neural system of sea
squirts occurs in ocean around 0.5 billion years
ago. It consists of about 300 neurons to adapt
to the environment.
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An Evolution of the Brain from Fish to Reptile
to Mammal
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The human brain
The first model of human brain appears in Africa
about 5 million years ago. It weights less than
1 pound. Within 3 million years, it increases to
1.5 pound. Homo habilis knew how to make tools.
In another million years, homo erectus discovered
fire and hunting. His brain is doubled in size.
A hundred thousand years ago, modern man arrived.
His brain is 3 times heavier and 4 times bigger
than the early human brain.
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Evolution of human brain
Early man (brain lt1 pound)
Homo habilis (brain 1.5 pound)
Homo erectus (brain 2 pound)
Modern man (brain 3 pound)
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Microscopic view of the brain
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Synapses
There are about 1015 synapses in human brain,
including electrical synapses and chemical
synapses. A synapse can be excitatory or
inhibitory.
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Excitatory vs. Inhibitory
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Signal Propagation along an Axon
v 1 100 m/sec
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The Hodgkin-Huxley Model
The total membrane current
Ionic reversal potential due to electric force
Hodgkin and Huxley assume that
n describes the fraction of activated potassium
channels m describes the fraction of activated
sodium channels h describes the fraction of
inactivated sodium channels
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For a two-state model
open
close
These rate constants are approximated by
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Microscopic view of neuron communication
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Brain Functions
motor
sensory
Brocas area
EMC2
olfactory
visual
auditory
Left brain logic, analytical abilities
language Right brain art, music,
creativity spatial perception
In general, the right brain controls movement on
the left side of the body and processes sensory
information originating from the left side
vice versa.