Dissertation/Thesis Abstract

Behavioral and electrophysiological investigation of early visual processing in the fly
by Tuthill, John C., Ph.D., The University of Chicago, 2012, 161; 3499800
Abstract (Summary)

The visual system of the fly is a highly stereotyped network of neurons that transforms external luminance signals into electrical potentials that can be processed by the nervous system. I studied the neural computations that occur at the earlier stages of visual processing in the vinegar fly, Drosophila Melanogaster. Chapter 1 of this thesis is an historical introduction to the study of the most peripheral neuropil of the fly optic lobes: the lamina. In Chapter 2, I examine fly perception of the reverse-phi motion illusion by measuring steering responses of tethered flies in a virtual reality flight simulator. Flies perceive the reverse-phi illusion in much the same way as humans, and the activity of neurons in the visual system reflects this sensitivity. Behavioral responses to reverse-phi motion constrain the neural computations that underlie visual motion detection. In Chapter 3, I describe a novel class of wide-field feedback neurons in the fly lamina, and study the effects of silencing these neurons on visually-guided behavior. Silencing wide-field neurons impairs discrimination of low contrast visual stimuli, and increases sensitivity to low frequency motion patterns. Electrophysiological recordings from wide-field neurons in Chapter 4 demonstrate that these neurons are selective for low frequency luminance fluctuations, suggesting that wide-field feedback suppresses low frequency signals in the lamina. The frequency sensitivity of wide-field neurons shifts dramatically during flight due to release of the neuromodulator octopamine. Chapter 5 summarizes the main findings in this thesis, and provides a commentary on our current and future understanding of visual processing in the fly.

Indexing (document details)
Advisor: Reiser, Michael
Commitee: Hale, Melina, MacLean, Jason, Margoliash, Daniel
School: The University of Chicago
Department: Biology
School Location: United States -- Illinois
Source: DAI-B 73/07(E), Dissertation Abstracts International
Subjects: Neurosciences, Physiology, Behavioral Sciences
Keywords: Behavior, Drosophila, Electrophysiology, Fly, Motion detection, Vision
Publication Number: 3499800
ISBN: 9781267248343
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