he use of evoked potentials to evaluate the functional integrity of neuronal pathways has become a useful and accepted practice in clinical medicine. The use of visual evoked potentials for assisting in the diagnosis of such diseases as optic neuritis and multiple sclerosis is also well recognized. However, the visual evoked potential, unlike the auditory evoked potentials, lacks a well defined electrophysiological to neuroanatomical correlation; especially that of a significant non-cortical component. Currently, visual evoked potentials rely principally on the measurement of a cortical (occipital) positive peak of activity at 100ms (P100), recorded with a single channel electrode system, to evaluate pathway integrity. In this study, visual evoked potentials were recorded using a three-channel, orthogonal co-ordinate system which we have designated "vector" visual evoked potentials (VVEP). This method allows the generated evoked response to be plotted on a three dimensional co-ordinate system with respect to time. Through the use of pattern reversal of a checkerboard pattern, in full and hemi retinal field stimulation, reproducible activity both prior to and afier the P100 wave was demonstrated. In particular, activity found at approximately 55ms is believed to be generated from the Lateral Geniculate Body. Furthermore, because this method summarizes the activity of the entire brain for a given time, as opposed to the single channel recording, a great deal of information about the entire visual pathway can be suggested. Finally, anatomical correlates to discrete activities identified by this method can be made.
| Identifer | oai:union.ndltd.org:vcu.edu/oai:scholarscompass.vcu.edu:etd-6186 |
| Date | 01 January 1990 |
| Creators | Siegel, Lance Mitchell |
| Publisher | VCU Scholars Compass |
| Source Sets | Virginia Commonwealth University |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | Theses and Dissertations |
| Rights | © The Author |
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