Abstract
Recent work has demonstrated that activity of neurons in the supplementary eye field (SEF) appears to signal the rule in an oculomotor decision task but not the behavioral decision. Here we tested whether the frontal eye fields (FEF) participate in a later stage of ocular decision making. Single-neuron activity was recorded from the SEF or the FEF while monkeys performed an ocular go/nogo task. The task rule is to smoothly pursue a moving target only after it intersects a visible plate region. The initial decision time, choice probability (CP), and directionality index (DI) of the neurons were computed. We found that SEF neurons encode the rule of the task mostly before plate intersection, whereas FEF neurons do so after plate intersection. In error trials SEF neurons continued to encode only the rule, whereas FEF neurons signal the behavioral choice. CP values for SEF neurons were greatest well before pursuit initiation and decreased afterwards, whereas CP values for FEF neurons increased and peaked immediately before movement initiation. The DI of SEF activity was low throughout the trial whereas that of FEF activity was greatest immediately before movement initiation but decreased later. The results suggest that the SEF can signal the rule early, but does not directly trigger the eye movements, whereas the FEF appears to specify the movement choice.