The Impact of Active Sensing on Visual Processing in the Mouse
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Date
2025-02-24
Authors
Sharp, Shelby
Journal Title
Journal ISSN
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Publisher
University of Oregon
Abstract
Vision is an active process that relies on one's ability to sample the visual scene through interactions with the environment. Traditionally, visual neuroscience has been investigated through restrained experimental conditions that limit animals to head-fixation and minimal locomotion on a spherical treadmill. To fully understand visual processing it is imperative that we utilize technological advances to study vision in more ethologically relevant experimental conditions. This dissertation lays out novel experimental methods and data analysis that enable the study of visual processing in freely moving mice during behavior. Chapter II of the dissertation explores how mice determine distance information during an ethologically inspired jumping task through eye and whole body video tracking, optogenetic shutdown of primary visual cortex (V1), and monocular occlusion. The study finds that mice use vision to accurately jump across gaps of varying distances. Additionally, mice are able to accurately perform this task with monocular occlusion suggesting that proper distance estimation is not dependent on binocular disparity or stereo vision. Further, optogenetic shut down of both monocular and binocular V1 impaired task performance indicating that integration of visual information in primary visual cortex is necessary to reliably estimate distance. Importantly this study acts as a cornerstone for future experiments investigating neural circuitry during ethologically relevant tasks.
Chapter III explores the impact of head and eye movements on visual processing in V1, focusing specifically on the role of gaze shifts during free movement. During head-fixation mice rarely make saccadic eye movements, and in fact most mouse eye movements occur during head movements. To overcome this limitation we designed an experimental paradigm to investigate gaze shifts during free movement. By combining neural data, eye and world view cameras, and an inertial measurement unit we evaluated the impact of gaze shifting head and eye movements on visual processing. This study uncovers a dynamic temporal sequence that occurs in V1 following gaze shifts, which is visually driven and is elicited by the influx of new visual information that occurs during saccadic movements. Further, these gaze shift dynamics are consistent with the computational principle of coarse-to-fine visual processing.
Chapter IV expands upon the previous freely moving gaze shift experimental methods to investigate the impact of head and eye movements on visual processing in a different brain region involved in visual processing, the superior colliculus (SC). This study explores the head and eye movement responses in SC across depth revealing differing gaze shift dynamics between superficial SC (sSC) and deep SC (dSC). Specifically, in sSC we see gaze shift responses that, like V1, correspond to coarse-to-fine processing and are visually driven; however, in dSC gaze shift responses reflect head movement signals that persist in the absence of visual information. We believe that this work shows for the first time the impact of free moving gaze shift responses across the layers of SC.
This dissertation consists of previously published and unpublished co-authored material.
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Keywords
active sensing, active vision, electrophysiology, movement, neuroscience, vision