STDP and the distribution of preferred phases in the whisker system

TL;DR

This study demonstrates how spike-timing-dependent plasticity (STDP) can explain the distribution of preferred phases in neurons involved in whisker-based sensory processing in rodents, resolving a discrepancy between expected and observed neural phase distributions.

Contribution

The paper introduces a modeling framework showing how STDP influences the distribution of preferred phases in downstream neurons, providing a novel explanation for empirical observations.

Findings

STDP facilitates rhythmic information transfer despite dynamic synapses.

Preferred phases of downstream neurons drift over time, creating a distribution.

The distribution of preferred phases is governed by the STDP rule.

Abstract

Rats and mice use their whiskers to probe the environment. By rhythmically swiping their whiskers back and forth they can detect the existence of an object, locate it, and identify its texture. Localization can be accomplished by inferring the position of the whisker. Rhythmic neurons that track the phase of the whisking cycle encode information about the azimuthal location of the whisker. These neurons are characterized by preferred phases of firing that are narrowly distributed. Consequently, pooling the rhythmic signal from several upstream neurons is expected to result in a much narrower distribution of preferred phases in the downstream population, which however has not been observed empirically. Here, we show how spike-timing-dependent plasticity (STDP) can provide a solution to this conundrum. We investigated the effect of STDP on the utility of a neural population to transmit rhythmic information downstream using the framework of a modeling study. We found that under a wide range of parameters, STDP facilitated the transfer of rhythmic information despite the fact that all the synaptic weights remained dynamic. As a result, the preferred phase of the downstream neuron was not fixed, but rather drifted in time at a drift velocity that depended on the preferred phase, thus inducing a distribution of preferred phases. We further analyzed how the STDP rule governs the distribution of preferred phases in the downstream population. This link between the STDP rule and the distribution of preferred phases constitutes a natural test for our theory.