The ventromedial prefrontal cortex (VMPFC) is an intriguing brain region which sends output to and receives input from memory, emotion and reward related structures such as the amygdala, hippocampus, and caudate nucleus. Humans with lesions to the VMPFC on the surface seem to function normally and most have normal intelligence. However, in high-level tasks blending affect and decision-making, they are often highly impaired. This thesis concerns three behavioral experiments of patients with VMPFC damage which contrast and examine hypotheses of VMPFC function. In Experiment 1, the hypothesis that the VMPFC is involved in representing social knowledge was tested with more rigorous methods and a non social control task. Results did not support a specific role of the VMPFC in social knowledge. In Experiments 2 & 3, the hypothesis that VMPFC is involved in rapid reversal of stimulus-reinforcer associations was examined in detail. A gambling task and a probabilistic learning task helped discriminate punishment versus reward processing. Experiment 2 revealed normal performance of VMPFC patients in a rewards-only reversal task, in contrast to performance on previous gambling tasks with both reversal and punishment. Experiment 3 added to this evidence for a special function in punishment processing by examining learning from punishment versus learning from reward. Results revealed deficits in punishment learning, but not reward learning, after damage to the VMPFC. In conclusion, these experiments suggest a special role for the VMPFC in punishment processing, especially when a change in stimulus choice is indicated.
| Identifer | oai:union.ndltd.org:PITT/oai:PITTETD:etd-04242006-135021 |
| Date | 21 June 2006 |
| Creators | Wheeler, Elizabeth Zabriskie |
| Contributors | Lesley Fellows, Greg Siegle, William Klein, Julie Fiez, Walter Schneider |
| Publisher | University of Pittsburgh |
| Source Sets | University of Pittsburgh |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.library.pitt.edu/ETD/available/etd-04242006-135021/ |
| 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 University of Pittsburgh 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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