Network dynamics underlying OFF responses in the auditory cortex

Across sensory systems, complex spatio-temporal patterns of neural activity arise following the onset (ON) and offset (OFF) of stimuli. While ON responses have been widely studied, the mechanisms generating OFF responses in cortical areas have so far not been fully elucidated. We examine here the hypothesis that OFF responses are single-cell signatures of network dynamics and propose a network model that generates transient OFF responses through recurrent interactions. To test this model, we performed population analyses of two-photon calcium recordings in the auditory cortex of awake mice listening to auditory stimuli. We found that the network model accounts for the low-dimensional organisation of population responses and their global structure across stimuli, where distinct stimuli activate mostly orthogonal dimensions in the neural state-space. In contrast, a single-cell mechanism explains some prominent features of the data, but does not account for the structure across stimuli and trials captured by the network model.