Frontal eye field lesions in monkeys disrupt visual pursuit

Discussions of the cortical control of eye movement have generally attributed the generation of saccadic movements to the frontal eye fields (FEF) and the control of pursuit movements to posterior parietal or prestriate cortex. Monkeys were trained to perform a series of oculomotor tasks, including both saccade and pursuit paradigms. Surgical ablation of the frontal eye fields produced only minor disruption of saccade performance, but caused a dramatic deficit in the ability of monkeys to visually track a slowly moving target. This disorder has not previously been associated with FEF lesions. These results necessitate a major re-evaluation of the way in which the cerebral cortex participates in oculomotor control.