Figure 1.

Methods. A, Sacc with multiple possible go cues. After a brief period of fixation, four gray possible go cues and one green saccade target appeared. One of the gray possible go cues increased in luminance after a random go time, indicating to the monkey to saccade toward the green target (indicated by the blue arrow). B, Arm with multiple possible go cues. The blue target indicated to the monkey to retract the arm (indicated with the blue arrow) ipsilateral to the target after the go signal. C, Fixation task with multiple distractors. The gray color of the fifth distractor, together with the lack of a go signal, indicated to the subject to maintain central fixation. D, Block design fMRI experiment showing, respectively, a Sacc task, a Fix task with five distractors, and an Arm task. Every task is presented for 40 s. During the actual experiment, the conditions were presented in random order in one cycle and a cycle was presented twice in each run. E, Monkey in sphinx position (adapted from Vanduffel et al., 2001). Red lines indicate the optic fibers for the infrared laser beams (a pair for the left and for the right hand). Fibers are positioned below and above the bar serving as rest position for the hand. Red dotted lines indicate the uninterrupted laser beam. The monkey had to retract the left hand when the target appeared in the left hemifield and the right arm when it appeared on the right. Blue arrow indicates the direction of the response movement.