Behavioral origin of sound-evoked activity in mouse visual cortex

Area of Science:

• Neuroscience
• Sensory processing
• Multisensory integration

Background:

• Sensory cortices, like the primary visual cortex (V1), are increasingly recognized as multisensory, responding to stimuli beyond their primary modality, such as sound.
• The neural mechanisms underlying multisensory responses in V1 and their relationship to other brain regions and behavioral states remain incompletely understood.

Purpose of the Study:

• To investigate the characteristics of sound-evoked neural activity in the primary visual cortex (V1).
• To determine the origin and dimensionality of multisensory responses in V1.
• To explore the relationship between sound-evoked V1 activity and behavioral responses.

Main Methods:

• Utilized Neuropixels probes for high-density neural recordings in the primary visual cortex (V1).
• Measured neural responses to auditory stimuli across different mice and neuronal populations.
• Analyzed the dimensionality of neural codes for visual and auditory stimuli.
• Correlated neural activity with concurrent body movements elicited by sounds.

Main Results:

• Sound-evoked activity in V1 was found to be highly stereotyped across neurons and individual mice.
• This activity was independent of direct auditory cortex projections and resembled patterns seen in the hippocampal formation.
• The neural code for sound in V1 was low-dimensional, contrasting with the high-dimensional visual code.
• Sound-evoked V1 activity was predictable from small, stereotyped body movements triggered by the sounds.

Conclusions:

• Apparently multisensory responses in V1 to sound may not originate from direct auditory processing.
• Low-dimensional neural activity in V1 related to sound is strongly associated with behavior-driven signals from body movements.
• Internal state and behavior, rather than direct cross-modal input, may explain some observed multisensory phenomena in sensory cortices.