Stochastic Approaches to Spike-timing dependent plasticity: Electrosensory adaptation

Roberts Patrick D.

Oregon Health & Science University 3181 S.W. Sam Jackson Park Rd. Portland, Oregon 97239-3098 USA

phone: + 1 (503) 494-8311 e-mail: robertpa@ohsu.edu

Abstract:

Many sensory systems adapt to repeated stimuli in order to eliminate predictable sensory patterns. An experimentally tractable sensory system that exhibits this adaptation is the electrosensory system of mormyrid electric fish. Electrosensory adaptation has been shown to rely on spike-timing dependent synaptic plasticity where the change in synaptic strength is dependent on the exact relative timing of pre- postsynaptic spikes. We have developed random walk methods to calculate the moments of synaptic weight equilibrium distributions will be discussed. The neural architecture of the model is based on the mormyrid electrosensory system, which forms a negative image of the fish’s own electric discharge to optimize detection of external electric fields. Of particular behavioral importance to the fish is the variance of the equilibrium postsynaptic potential in the presence of noise, which is determined by the variance of the equilibrium weight distribution. Recurrence relations have been derived for the moments of the equilibrium weight distribution, for arbitrary postsynaptic potential functions and arbitrary learning rules.