Offset Responses in the Auditory Cortex Show Unique History Dependence

Sensory responses typically vary depending on the recent history of sensory experience. This is essential for processes, includ-ing adaptation, efficient coding, and change detection. In the auditory cortex (AC), the short-term history dependence of sound-evoked (onset) responses has been well characterized. Yet many AC neurons also respond to sound terminations, and little is known about the history dependence of these offset responses, whether the short-term dynamics of onset and offset responses are correlated, or how these properties are distributed among cell types. Here we presented awake male and female mice with repeating noise burst stimuli while recording single-unit activity from primary AC. We identified parvalbumin and somatostatin interneurons through optotagging, and also separated narrow-spiking from broad-spiking units. We found that offset responses are typically less depressive than onset responses, and this result was robust to a variety of stimulus parame-ters, controls, measurement types, and selection criteria. Whether a cell's onset response facilitates or depresses does not pre-dict whether its offset response facilitates or depresses. Cell types differed in the dynamics of their onset responses, and in the prevalence, but not the dynamics, of their offset responses. Finally, we clustered cells according to spiking responses and found that response clusters were associated with cell type. Each cluster contained cells of several types, but even within a cluster, cells often showed cell type-specific response dynamics. We conclude that onset and offset responses are differentially influenced by recent sound history, and discuss the implications of this for the encoding of ongoing sound stimuli.

Automated summary

This study investigated the characteristics of different cell types and the differences between onset and offset responses. The results showed that offset responses are generally less depressive than onset responses, and the dynamics of onset responses do not predict the dynamics of offset responses. Different cell types exhibit variations in the dynamics of their onset responses and the prevalence of their offset responses. Response clusters are associated with cell type.