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Lecture 4 (Wed, 9/10)
Chapter 3: Biological Basis of Learning and Memory
3.1 Memory Networks in the Brain
3.2 Biomolecular Mechanisms for Synaptic Learning and Memory
3.3 Principles of Molecular Information Processing for Learning and Memory
3.1 Memory Networks in the Brain
Physical Scales in
Computational Neurobiology
organ
system
(cm)
Information
Processing
increasing
structural
realism
cellular
(mm to μm)
subcellular
(μm to nm)
molecular
(angstroms)
Neural Networks
Groups of Neurons
Single Neurons
Groups of Synapses
Single Synapses
Groups of
Neurotransmitters
(molecules)
Molecular Dynamics
Memory Networks at Three Levels
- Cortical network (between the cell assemblies)
- Synaptic network (between the cells)
- Molecular network (within a cell)
3.2 Biomolecular Mechanisms for Synaptic Learning and Memory
Note: Figures captured from [Kandel-06].
- Learning and memory can be explained at the cellular and molecular levels.
- The location of learning and memory is synapses.
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Learning is involved with physical change of synapses by protein synthesis.
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Molecular information processing such as chemical synaptic transmission involves with memory and
learning.
Chemical nature of information processing in the brain
-
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Electrical signals at the cellular level are based on the chemistry at the molecular level.
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Thus, modeling the information processing in the brain at the molecular level may shed
light on that at the cellular level.
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Related question: Explaining the properties of matter based on particles in physics
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Understanding the structure of composite material based on atoms and molecules in
chemistry.
Chemical nature of synaptic transmission
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The transmission of electrical signals are based on the underlying chemical signal
transduction at the molecular level.
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Chemistry is important in understanding the principles of cognitive learning and
memory.
Questions:
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Is brain an electrical computer or a chemical computer?
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Related question: Is light a wave or a particle?
Electrical  Chemical  Electrical
Biochemical mechanisms of short-term memory
- Signal transmission in a synapse is based on the lock-key mechanism between the
ligands and the receptors.
- Short-term memory is stored by strengthening the chemical transmission
mechanisms through secreting neurotransmitters at the synapses.
-
- Short-term memory does not involve nucleus but the long-term memory does.
- Short-term memory involves functional changes at a single synapse, but long-term
memory changes the anatomical or structural changes of the synapses.
Long-term memory and gene expression
(Relationship between synapse and gene)
Q: How the proteins synthesized can be transported to the synapses to learn?
Note: Signal broadcasting in a radio station
A: The synthesized proteins are transported to various synapses, but the synapses that are
stimulated by serotonins receive the proteins and grow the axon terminals.
9/22 (Mon)
3.3 Principles of Molecular Information Processing for Learning and
Memory
Visualization of Synaptic Cleft