Homeostasis and Receptive Field Plasticity

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• Homeostasis and Receptive Field Plasticity
• RF plasticity with the CaDP model
• Synaptic scaling
• Metaplasticity
• RF plasticity with CaDP Metaplasticity

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Assume CaDP model as in previous class
1. 2. 3.
Input structure
How is this done?
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Model Consequences at system level
Input structure
uncorrelated
correlated
rate
0 50 100
The system is not robust
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Review of Homeostatic mechanisms 1. Synaptic
scaling
Review by Turrigiano and Nelson 2000
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Synaptic scaling is a description of a phenomena,
not a mechanism
Possible Mechanism
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Metaplasticity The experience dependent change
in the functional form of synaptic
plasticity. There are many examples, we will
concentrate on one type of metaplasticity.
Kirkwood et al 1996
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• Possible molecular basis for this change in
  threshold
• Change in NMDAR composition (Quinlan et al 1999,
  Philpot et. al 2001) or number (Watt et. al.
  2004) produced by dark rearing.
• Activity dependent change in Ih previous lecture
  by Dan Johnston.

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Metaplasticity activity dependent change in
synaptic plasticity
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Effects of metaplasticity with poisson inputs
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Different time scales for plasticity and
metaplasticity
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Plasticity with correlated and uncorrelated group
The spike-triggered presynaptic event density
(STPED)
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Segregation between correlated and uncorrelated
channels is robust.
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Segregation with two correlated groups
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Selectivity to non-static, non-overlapping square
patterns of input rate distribution.
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Selectivity to non-static, overlapping Gaussian
patterns of input rate distribution.
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Summary