Exploring the neural basis of visual processing in the freely moving mouse

1 page.Historically, the sensory regions of the mammalian brain have been characterized as processing centers for single modalities—for example, visual cortex processes vision. It has since been found that sensory regions are not truly segregated in function, however, and signals related to other aspects of perception, for example movement signals from motor regions, are also integrated into the neural activity of these sensory areas. Due to the technical challenge of recording from single neurons in freely-moving animals and maintaining control over sensory input, the mechanisms underlying this integration have yet to be specifically characterized, and as such the extent to which non-visual signals impact visual processing is unknown. We developed a technique to record freely-moving electrophysiology data while simultaneously recording visual input and motor actions in a naturalistic setting for the freely-moving mouse. To achieve this, we chronically implant multisite silicon recording electrodes in the primary visual cortex (V1), which can record up to 64 neurons at a time. In addition, we attach a 3-D printed device containing a camera for recording eye position, a camera for recording the animal’s visual scene, and an inertial measurement unit to record head orientation and movements during experimental recordings. By aligning and integrating all of these data into an analysis pipeline, we found individual neurons in V1 to show response tuning for both specific motor actions—such as head orientation movements and compensatory eye movements and saccades—as well as for specific visual stimuli, revealing the nuanced integration of both visual and non-visual signals in visual cortex that allows for successful perception of the world