SACCADE TARGET SELECTION IN FRONTAL EYE FIELD OF MACAQUE .1. VISUAL AND PREMOVEMENT ACTIVATION

We investigated how the brain selects the targets for eye movements, a process in which the outcome of visual processing is converted into g uided action. Macaque monkeys were trained to make a saccade to fixate a salient target presented either alone or with multiple distracters during visual search. Neural activity was recorded in the frontal eye field, a cortical area at the interface of visual processing and eye m ovement production. Neurons discharging after stimulus presentation an d before saccade initiation were analyzed. The initial visual response of frontal eye field neurons was modulated by the presence of multipl e stimuli and by whether a saccade was going to be produced, but the i nitial visual response did not discriminate the target of the search a rray from the distracters. In the latent period before saccade initiat ion, the activity of most visually responsive cells evolved to signal the location of the target. Target selection occurred through suppress ion of distracter evoked activity contingent on the location of the ta rget relative to the receptive field. The evolution of a signal specif ying the location of the salient target could be dissociated from sacc ade initiation in some cells and could occur even when fixation was ma intained. Neural activity in the frontal eye fields may participate in or be the product of the decision process guiding eye movements.