Functional MRI in macaque monkeys during task switching.

Non-human primates have proven to be a valuable animal model for exploring neuronal mechanisms of cognitive control. One important aspect of executive control is the ability to switch from one task to another, and task-switching paradigms have often been used in human volunteers to uncover the underlying neuronal processes. To date however, no study has investigated task-switching paradigms in non-human primates during functional magnetic resonance imaging. We trained two rhesus macaques to switch between arm movement, eye movement and passive fixation tasks during fMRI. Similar to results obtained in human volunteers, task-switching elicits increased fMRI activations in prefrontal cortex, anterior cingulate cortex, orbitofrontal cortex and caudate nucleus. Our results indicate that the macaque monkey is a reliable model with which to investigate higher-order cognitive functioning such as task-switching. As such, these results can pave the way for a detailed investigation of the neural basis of complex human behavior. SIGNIFICANCE STATEMENT Task-switching is an important aspect of cognitive control, and task-switching paradigms have often been used to investigate higher order executive functioning in human volunteers. We used a task-switching paradigm in the non-human primate during fMRI, and found increased activation mainly in prefrontal areas (46, 45, FEF and anterior cingulate), in orbitofrontal area 12 and the caudate nucleus. These data fit surprisingly well with previous human imaging data, proving that the monkey is an excellent model to study task switching with high spatio-temporal resolution tools that are currently not applicable in humans. As such our results pave the way for a detailed interrogation of regions performing similar executive functions in humans and monkeys.