Bursts generate a non-reducible spike pattern code

TL;DR

This study demonstrates that burst-like spike patterns in grasshopper auditory receptors encode behaviorally relevant stimuli, with specific burst features representing different stimulus aspects, highlighting the importance of temporal spike patterns in neural coding.

Contribution

It provides experimental evidence that burst patterns encode stimulus features and timing, supporting the significance of spike-pattern codes in neural information transmission.

Findings

Burst patterns encode stimulus features with different spike counts.

Approximately 20% of information relates to stimulus discrimination.

Remaining 80% of information encodes timing of stimulus features.

Abstract

At the single-neuron level, precisely timed spikes can either constitute firing-rate codes or spike-pattern codes that utilize the relative timing between consecutive spikes. There has been little experimental support for the hypothesis that such temporal patterns contribute substantially to information transmission. By using grasshopper auditory receptors as a model system, we show that correlations between spikes can be used to represent behaviorally relevant stimuli. The correlations reflect the inner structure of the spike train: a succession of burst-like patterns. We demonstrate that bursts with different spike counts encode different stimulus features, such that about 20% of the transmitted information corresponds to discriminating between different features, and the remaining 80% is used to allocate these features in time. In this spike-pattern code, the what and the when of the stimuli are encoded in the duration of each burst and the time of burst onset, respectively. Given the ubiquity of burst firing, we expect similar findings also for other neural systems.