Behavioral origin of sound-evoked activity in mouse visual cortex

Sensory cortices can be affected by stimuli of multiple modalities and are thus increasingly thought to be multisensory. For instance, primary visual cortex (V1) is influenced not only by images but also by sounds. Here we show that the activity evoked by sounds in V1, measured with Neuropixels probes, is stereotyped across neurons and even across mice. It is independent of projections from auditory cortex and resembles activity evoked in the hippocampal formation, which receives little direct auditory input. Its low-dimensional nature starkly contrasts the high-dimensional code that V1 uses to represent images. Furthermore, this sound-evoked activity can be precisely predicted by small body movements that are elicited by each sound and are stereotyped across trials and mice. Thus, neural activity that is apparently multisensory may simply arise from low-dimensional signals associated with internal state and behavior.

Automated summary

Sensory cortices are considered to be multisensory, as they can be influenced by stimuli of multiple modalities. This study shows that the activity evoked by sounds in the primary visual cortex (V1) is stereotyped across neurons and mice, independent of projections from the auditory cortex. The low-dimensional nature of this activity contrasts with the high-dimensional code used by V1 for representing images. Furthermore, the sound-evoked activity can be accurately predicted by small body movements that are consistent across trials and mice, suggesting that apparent multisensory neural activity may arise from low-dimensional signals associated with internal state and behavior.