Sound offset responses become highly informative in the auditory cortex

The entire auditory system downstream of the cochlea features pronounced offset responses that follow the termination of sounds. Because of their ubiquity, it remains an unsolved question whether offset responses are generated early in the auditory system and subsequently propagated downstream or recomputed at each processing stage. Here, we analysed large-scale sound response datasets acquired in the cochlear nucleus, inferior colliculus, medial geniculate nucleus and auditory cortex of awake mice. All brain regions showed a significant proportion of offset responses, often combined with onset and sustained responses in the same neuron. However, using population activity decoders, we observed that neural representations after the sound offset show a three-fold increase in sound encoding accuracy in the cortex relative to subcortical areas. This result indicates that cortical offsets encode a more precise short-term memory of the elapsed sound than subcortical offsets and that they probably result from specific computational steps. KEY POINTS: Offset responses are found throughout the central auditory system. Offset responses are often combined with sustained and onset responses at all central auditory system stages. Offset responses provide richer information about elapsed sounds in the auditory cortex.