In everyday life, we integrate visual and auditory information in routine tasks such as navigation and communication. While it is known that concurrent sound can improve visual perception, the neuronal correlates of this audiovisual integration are not fully understood. Specifically, it remains unknown whether improvement of the detection and discriminability of visual stimuli due to sound is reflected in the neuronal firing patterns in the primary visual cortex (V1). Furthermore, presentation of the sound can induce movement in the subject, but little is understood about whether and how sound-induced movement contributes to V1 neuronal activity. Here, we investigated how sound and movement interact to modulate V1 visual responses in awake, head-fixed mice and whether this interaction improves neuronal encoding of the visual stimulus. We presented visual drifting gratings with and without simultaneous auditory white noise to awake mice while recording mouse movement and V1 neuronal activity. Sound modulated the light-evoked activity of 80% of light-responsive neurons, with 95% of neurons exhibiting increased activity when the auditory stimulus was present. Sound consistently induced movement. However, a generalized linear model revealed that sound and movement had distinct and complementary effects of the neuronal visual responses. Furthermore, decoding of the visual stimulus from the neuronal activity was improved with sound, an effect that persisted even when controlling for movement. These results demonstrate that sound and movement modulate visual responses in complementary ways, resulting in improved neuronal representation of the visual stimulus. This study clarifies the role of movement as a potential confound in neuronal audiovisual responses, and expands our knowledge of how multi-modal processing is mediated at a neuronal level in the awake brain.
Homeostatic plasticity mechanisms in mouse V1