Oculomotor control networks in the macaque brain

The planning and execution of eye movements relies on a network of cerebral cortical areas that must transform sensory signals into motor commands. While key parietal and frontal cortical areas appear to perform this transformation, the precise locations and functional organization of these areas remains unclear. Anatomical localization of the components underlying oculomotor control is needed to resolve this issue. This dissertation investigates the cerebral components of the oculomotor control system in the macaque brain, and provides a new approach for anatomical localization of function in the macaque cerebral cortex.; First, we applied functional magnetic resonance imaging (fMRI) in awake, behaving monkeys performing rapid (saccadic) and smooth (pursuit) eye movements, as well as active fixation. We measured hemodynamic signals throughout the brain during task performance and linked them to specific types of eye movements using linear regression. The analyses provided maps of the brain areas that were active during saccadic and pursuit eye movements, and also the directionality (i.e., spatial biases) of these responses. We found that saccades and pursuits engage distinct regions of the macaque lateral frontal cortex. Saccades generated a larger than expected activation of the temporal motion processing complex, but less activation than expected in the parietal and dorsomedial frontal cortices. Visual stimulation during active fixation generated large responses in occipital and temporal cortices, but almost no response in parietal or frontal cortices.; Second, we developed a new method using structural MRI to provide anatomical localization for electrophysiological studies. This quantitative strategy provides a robust and practical way for neurophysiologists to guide and report their chronic experiments using behaving animals by projecting recording chamber geometry onto the underlying brain tissue. We used this method to localize two regions of the movement planning system in the frontal and parietal cortices, and also to make the crucial observation that recording chambers move over time.