Primate premotor cortex: modulation of preparatory neuronal activity by gaze angle.
1. This study investigated whether the neuronal activity of a cortical area devoted to the control of limb movements is affected by variations in eye position within the orbit. Two rhesus monkeys were trained to perform a conditional visuomotor task with an instructed delay period while maintaining gaze on a fixation point. 2. The experimental design required each monkey to put its hand on a metal touch pad located at arm's length and fixate a small spot of light presented on a computer screen. Then a visual cue came on, at the fixation point or elsewhere, the color of which instructed the monkey to move its limb to one of two touch pads according to a conditional rule. A red cue meant a movement to the left, whereas a green one instructed a movement to the right. The cue lasted for a variable delay period (1-3 s), and the monkey had to wait for its offset, the go signal, before performing the correct response. The fixation point and the cues were presented at various screen locations in a combination that allowed examination of whether eye position and/or target position modulate the neuronal activity. Because the monkeys' heads were fixed, all changes in eye position reflected movements in a craniocentric, head-centered, coordinate space. 3. The activity of single neurons was recorded from dorsal premotor cortex (PMd). For most neurons (79%), the activity during the instructed delay period (set-related activity) reflects the direction of the upcoming limb movement but varies significantly with eye position.(ABSTRACT TRUNCATED AT 250 WORDS)
Boussaoud
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Vision et Motricité, Institut National de la Santé et de la Recherche Médicale U94, Bron, France.
D000818:Animals; D004594:Electrophysiology; D005403:Fixation, Ocular / Q000502:physiology*; D008253:Macaca mulatta; D008297:Male; D009044:Motor Cortex / Q000166:cytology / Q000502:physiology*; D009474:Neurons / Q000502:physiology*