Kinetic models of spike-timing dependent plasticity and their
functional consequences in detecting correlations
Quan Zou and Alain Destexhe
Biological Cybernetics 97: 81-97, 2007.
Abstract
Spike-timing dependent plasticity (STDP) is a type of synaptic
modification found relatively recently, but the underlying
biophysical mechanisms are still unclear. Several models of STDP
have been proposed, and differ by their implementation, and in
particular how synaptic weights saturate to their minimal and maximal
values. We analyze here kinetic models of transmitter-receptor
interaction and derive a series of STDP models. In general, such
kinetic models predict progressive saturation of the weights.
Various forms can be obtained depending on the hypotheses made in the
kinetic model, and these include a simple linear dependence on the
value of the weight ("soft bounds"), mixed soft and abrupt saturation
("hard bound"), or more complex forms. We analyze in more detail
simple soft-bound models of Hebbian and anti-Hebbian STDP, in which
nonlinear spike interactions (triplets) are taken into account. We
show that Hebbian STDP can be used to selectively potentiate synapses
that are correlated in time, while anti-Hebbian STDP depress
correlated synapses, despite the presence of nonlinear spike
interactions. This correlation detection enables neurons to develop
a selectivity to correlated inputs. We also examine different
versions of kinetics-based STDP models and compare their sensitivity
to correlations. We conclude that kinetic models generally predict
soft-bound dynamics, and that such models seem ideal for detecting
correlations among large numbers of inputs.
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