Dynamic Visual Processing: Creating Representations of the World
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Date
2020-02-27
Authors
Michaiel, Angie
Journal Title
Journal ISSN
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Publisher
University of Oregon
Abstract
Vision is a vital sense upon which our experience of the world is built. Classical views of vision designate it as a purely feedforward process where external visual information from the environment is passively processed within the brain. More recent work has revealed that vision is more dynamic; the brain has the ability to also utilize information from internal representations of current and future goals, context, and learned expectations to build more adaptive perceptual representations and sensorimotor transformations. The aim of this dissertation is to examine vision in both the context of disrupted visual processing (i.e., altered internal representations) and goal directed visual behavior in order to understand the dynamic nature of vision.
In this thesis, I describe two dissimilar approaches to examine these different aspects of visual processing in the mammalian brain. In the first approach, covered in Chapter II, I describe experiments and results in which neural substrates known to mediate accurate visual perception were perturbed using a hallucinogenic compound that activates serotonin-2A receptors. Using multiple methods, we observed that agonizing this receptor subtype leads to a strong reduction in sensory-driven visual cortical activity, potentially placing more reliance on internal representations and expectations of the world, which may work to generate hallucinations and sensory disruptions.
This first approach followed traditional methods of visual neurophysiology, in which mechanisms of visual processing were manipulated and observed in an unnatural but well controlled context. However, paradigms such as this dramatically limit natural exploration of the visual environment, which is naturally achieved through directed eye, head, and body movements. In Chapter III I will describe a system I designed to record bilateral eye movements while unrestrained mice perform a visually guided, goal directed behavior, capture of live insect prey. Utilizing this technique, we are beginning to understand the coordination of eye and head movements during active vision in the context of natural, goal-directed behavior. Here, I describe two opposing approaches to understand dynamic visual processing, ultimately answering longstanding questions about how the brain allows organisms to interact in their environments.
This dissertation includes previously published co-authored material.
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Keywords
eye movements, hallucinogens, neurobiology, saccades, visual cortex, Visual Processing