Max Planck Institute for Dynamics and Self-Organization -- Department for Nonlinear Dynamics and Network Dynamics Group
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Tuesday, 07.02.2012 17 c.t.

When two is not enough: using triplets of spikes to model synaptic plasticity

by Dr. Julijana Gjorgjieva
from Center for Brain Science, Harvard University, Cambridge, MA, USA

Contact person: Fred Wolf


Ludwig Prandtl lecture hall


Synaptic plasticity depends on the precise timing of presynaptic and postsynaptic spikes and is believed to provide the basis for learning and memory. Traditionally, pairs of spikes have been assumed to be the building blocks governing synaptic change. If a presynaptic spike precedes a postsynaptic spike, synapses undergo long-term potentiation, whereas if the order is reversed, synaptic strength is depressed (known as spike timing-dependent plasticity, or STDP). Recent work has suggested that it is more appropriate to describe synaptic plasticity as a function of triplets of spikes (1 pre and 2 post). I will describe a triplet STDP model which can capture a variety of experimental data, and present a novel theoretical analysis of the model which has previously only been studied numerically. Under certain conditions, a direct correspondence can be made between the triplet STDP rule and the rate-based Bienenstock-Cooper-Munro (BCM) plasticity rule. The latter model has been shown to maximize the selectivity of the postsynaptic neuron, and thereby offers a possible explanation for experience-dependent cortical plasticity such as orientation selectivity. The analysis of the triplet STDP rule can be extended to spatio-temporal correlations of higher-than-second order, thus generalizing selectivity to patterns with higher-order correlations which exist in natural stimuli and have been measured in the brain. Finally, I show that this sensitivity of the triplet STDP rule to higher-order correlations can be used to develop direction and speed selectivity.

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