While it is known that acute and chronic stress can impact cognition, less is known about the immediate impacts of minor frustrations or positive experiences on subsequent behavior and cognition in primates. This study used a novel methodology to engineer both a positive and (slightly) frustrating experience, using the same apparatus, in 15 adult capuchin monkeys. Subjects were presented with a working memory task (DMTS) for 30 minutes after the experimental manipulations (or a control). As predicted, the frustrating task prior to testing resulted in a decrease in performance on the DMTS compared to performance after a positive experience or the control. Contrary to predictions, a positive experience did not facilitate performance to higher levels than the control condition. Manipulations also impacted several behaviors. Although there may be different results in different contexts, these results indicate that even mild negative experiences impact subsequent behavior and cognition in primates.

Functional magnetic resonance imaging (fMRI) is a relatively new tool that has been used to examine patterns of neural activation within those with traumatic brain injuries (TBI). A review of relevant literature is presented, including alterations in activity within the frontal and parietal regions that are thought to be compensatory in nature. In addition, possible explanations for discrepancies within this research are discussed. The current study expands upon previous work by incorporating a delayed-match-to-sample (DMS) task within an event-related paradigm and neuropsychological testing to compare 12 individuals with a history of TBI to 12 control participants with orthopedic injuries (OI). Participants in the TBI group were high functioning and in the chronic stage of recovery. Neuropsychological testing revealed statistically significant group differences in measures of working memory, processing speed, memory, and executive functioning. However, groups were comparable in accuracy on the DMS task. Percent signal changes in fMRI data revealed statistically significantly increased activation within the right dorsolateral prefrontal cortex (BA 46) for the TBI group compared to controls. Additional alterations in activation were found between groups within the inferior temporal (BA 37) and parietal (BA 7) regions. Regression analyses showed no relationship between neuropsychological testing and percent signal change within BA 46, but predictive relationships between testing and BA 37 and BA 7. Logistic regression analyses suggest that fMRI data did not add any incremental predictive value beyond neuropsychological testing alone when attempting to predict group (TBI vs. OI) membership.