Electronic Thesis and Dissertation Repository


Master of Science




Dr. Kevin Johnston


A key characteristic of selective visual attention is that it may be deployed on the basis of our knowledge or goals of the task at hand. Here, we used cryogenic deactivation to investigate the contribution of the dorsolateral PFC to cognitive flexibility and working memory, as well as their relation to the deployment of attention. Macaque monkeys performed visual search tasks requiring them to foveate a target in an array of stimuli. These included a feature search, a constant-target conjunction search, a variable-target search and variable-target with delay search task, with each being more cognitively demanding than the last. Bilateral deactivation of the DLPFC during more demanding tasks resulted in increased reaction time and decreased accuracy. These effects on visual search performance suggest that the DLPFC is involved in the deployment of attention to a target, and also contributes to the flexible and mnemonic processes needed when task demands increase.