I have studied the neurophysiological bases of saccade execution and evaluation within the oculomotor system of Macaca mulatta and Macaca radiata. To better understand saccade execution, I recorded the electromyogram (EMG) from extraocular muscles and the occurrence of microsaccades while monkeys canceled responses in the saccade stop-signal task. I found reduction in extraocular EMG and in the occurrence of microsaccades when monkeys canceled eye movements. These results are unanticipated by a well-accepted, new theory of saccade execution. I conclude that the theory's proposed mechanism of fixation is incomplete. To study saccade evaluation, I recorded activity from single neurons, small neural ensembles, and large groups of neurons in and overlying an area of frontal medial cortex called the supplementary eye field (SEF) while monkeys viewed light flashes or made correct and errant responses during the saccade stop-signal task. I found 1) that SEF displays functional microcircuitry very similar to that described in early sensory cortex even though anatomy differs drastically between these areas, 2) that monkeys display electrophysiological correlates of error detection homologous to the error related negativity (ERN) and error related positivity (Pe) recorded in humans, and 3) that current flow in SEF contributes to, but is not the sole determinant of the ERN. This work highlights differences between the oculomotor and spinal motor systems, suggests the need for improvements on current models of fixation, and provides novel insight on the neural basis of performance monitoring.
| Identifer | oai:union.ndltd.org:VANDERBILT/oai:VANDERBILTETD:etd-09202013-123341 |
| Date | 20 September 2013 |
| Creators | Godlove, David Christian |
| Contributors | David H. Zald, Gordon B. Logan, Okihide Hikosaka, Geoffrey F. Woodman, Jeffrey D. Schall |
| Publisher | VANDERBILT |
| Source Sets | Vanderbilt University Theses |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.library.vanderbilt.edu/available/etd-09202013-123341/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to Vanderbilt University or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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