Synaptic Time-Dependent Plasticity Increases Signal Transmission Speed

Synaptic time-dependent plasticity (STDP) is a biological mechanism which changes the strength of the connections between two neurons depending on the timing of the spikes in the pre- and postsynaptic neurons. Many studies relate STDP to the development of input selectivity and temporal coding, but time and energy efficiency is usually not studied. This work focuses on the property of STDP to reduce latencies, which has only been briefly addressed (Song, Miller & Abbot, Nat. Neuroscience 2001). As a trivial example, suppose three presynaptic neurons consistently trigger a postsynaptic spike; by STDP, their strengths increase to the point where only two synapses are necessary. Since the first two synapses always arrive before the third, the postsynaptic spike is triggered earlier. We extend this notion to populations of neurons and to account for inhibitory plasticity. Our work relates the system-level goal of speeding computation to a mechanistic, neuron level rule.