Learning direction selectivity through spike-timing dependent modification of neurotransmitter release probability

Abstract

It has recently been proposed that the direction selectivity of simple cells emerges from an interplay of depressing and non-depressing synapses projecting in an asymmetric arrangement onto these cells. We show that such an asymmetric arrangement may develop from a temporally asymmetric spike-based learning rule. The rule redistributes the probability of vesicle discharge, producing synapses with high discharge probability and strong depression in one-half of the receptive field and low discharge probability and weak depression in the other. This spatial shift together with the temporal phase advance of the depressing synapses adds up with the response of the surrounding non-depressing synapses only when the stimulus moves in the preferred direction.