http://hdl.handle.net/10090/806 Search the Channel search http://dspace.nitle.org/simple-search http://hdl.handle.net/10090/810 Title: N400 ERP Response as a Measurement of Semantic Expectancy in Trauma Survivors <br/> <br/>Authors: Batterink, Laura <br/> <br/>Abstract: Semantic biases in trauma survivors were assessed using the N400 ERP response as a measurement of expectancy. Eighteen trauma survivors were recruited from the community. Subjects were interviewed and their post-traumatic stress disorder diagnosis was determined by a clinical psychologist. Ambiguous sentences that could be sensibly completed with a military or non-military ending were presented to subjects one word at a time. The sentences ended with expected, unexpected, or military words. Subjects&#8217; EEG was continuously recorded throughout the task. Subjects with PTSD were found to have a reduced N400 response across all three conditions compared to subjects with no PTSD. The PTSD group also trended toward an inverted N400 pattern than normally seen in a healthy population. War veterans with PTSD showed a nearly significant reduction in N400 amplitude to the trauma condition relative to the unexpected condition. These findings provide more evidence for general cognitive deficiencies associated with PTSD, such as attentional problems, rather than differences in semantic expectancy in this population. However, there is some evidence to suggest that informationprocessing biases may also play a role in these differences. Future research should repeat this experimental design with a larger and less variable subject pool to substantiate these initial findings. <br/> <br/>Description: Submitted in Partial Fulfillment of Requirements For the Degree of Bachelor of Arts, Program in Neuroscience, Middlebury College http://hdl.handle.net/10090/809 Title: Neurochemical Mechanisms of Glucose-induced Cognitive Enhancement: <br/> <br/>Authors: Fong, Chui Ying (Rachel) <br/> <br/>Abstract: Extensive research has found that glucose enhances memory in healthy young adults as well as in elderly people. Rodent studies have also shown that administration of glucose, via intraseptal, intrahippocampal and systemic injections, facilitates learning and attenuates age-related cognitive deficits. A potential mechanism by which glucose may enhance memory is through interaction with the mesolimbic dopaminergic system. The mesolimbic dopamine system has long been suggested to mediate the brain reward pathway, which can induce learning and approach behavior. Moreover, recent theories also propose that dopamine may act as a marker for salient environmental stimuli and underlie motivated behavior. We hypothesized that different dopamine receptors would mediate the glucose-induced cognitive enhancement since ATP-sensitive potassium channels have been found to link glucose metabolism and neuronal excitability, which in turn modulates dopamine release. Spontaneous alternation was used to assess male Sprague-Dawley rats&#8217; spatial working memory after systemic administrations of glucose and selective D1 antagonist, SCH 23390, or D2 antagonist, eticlopride. Glucose was found to improve alternation performance compared to control rats. SCH 23390 and eticlopride blocked the glucose facilitation to a similar extent when injected with glucose, but they did not alter the subjects&#8217; alternation scores when injected with saline. No significant treatment-dependent difference was observed in the total numbers of arm entries or the temporal pattern of arm entries between all groups, indicating that the selected doses of dopamine antagonists did not produce motor or motivational deficits; the drug effects were likely to be cognitive. <br/> <br/>Description: Submitted in Partial Fulfillment of Requirements For the Degree of Bachelor of Arts, Program in Neuroscience, Middlebury College