Triple dissociation of visual, auditory and motor processing in primary visual cortex

Abstract

Primary sensory cortices respond to crossmodal stimuli, for example auditory responses are found in primary visual cortex (V1). However, it remains unclear whether these responses reflect sensory inputs or behavioural modulation through sound-evoked body movement. We address this controversy by showing that sound-evoked activity in V1 of awake mice can be dissociated into auditory and behavioural components with distinct spatiotemporal profiles. The auditory component began at ∼27 ms, was found in superficial and deep layers and originated from auditory cortex, as shown by inactivation by muscimol. Sound-evoked orofacial movements correlated with V1 neural activity starting at ∼80-100 ms and explained auditory frequency-tuning. Visual, auditory and motor activity were expressed by segregated neuronal populations and during simultaneous audiovisual stimulation, visual representations remained dissociable from auditory and motor-related activity. This threefold dissociability of auditory, motor and visual processing is central to understanding how distinct inputs to visual cortex interact to support vision.