Exploring Cognitive States of the Macaque Monkey with fMRI

This thesis describes experiments with macaque monkeys that were trained to perform several variants of a Delayed match to sample task inside a 3T Siemens Allegra scanner while functional whole brain images were acquired. In these tasks, a stream of shapes is shown in the lower left or right visual hemifield. The monkeys had to memorise the initial shape and give a manual response when a matching shape occurred. Different task variants were used that manipulated the demands for memory and attention. A GLM analysis was applied to identify brain regions with an increased BOLD signal during the delay period. The response profile of selected regions of interest was further characterised in more detail by using an approach based on extensive trial averaging. A distributed network of brain regions was robustly found across paradigms and monkeys. The results demonstrate the feasibility of fMRI experiments with primates performing cognitive tasks, but also yielded some unexpected findings.