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.
|Commitee:||Hale, Melina, MacLean, Jason, Margoliash, Daniel|
|School:||The University of Chicago|
|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|
Copyright in each Dissertation and Thesis is retained by the author. All Rights Reserved
The supplemental file or files you are about to download were provided to ProQuest by the author as part of a
dissertation or thesis. The supplemental files are provided "AS IS" without warranty. ProQuest is not responsible for the
content, format or impact on the supplemental file(s) on our system. in some cases, the file type may be unknown or
may be a .exe file. We recommend caution as you open such files.
Copyright of the original materials contained in the supplemental file is retained by the author and your access to the
supplemental files is subject to the ProQuest Terms and Conditions of use.
Depending on the size of the file(s) you are downloading, the system may take some time to download them. Please be