DIFFERENTIAL EFFECTS OF MUSCIMOL MICROINJECTION INTO DORSAL AND VENTRAL ASPECTS OF THE PREMOTOR CORTEX OF MONKEYS

1. A gamma aminobutyric acid (GABAA) receptor agonist, muscimol (Sigma, 5 micrograms/microliters solution), and a GABAB receptor agonist and antagonist, baclofen and phaclofen, respectively, were injected (1.0 microliter) into the dorsal and ventral aspects of the premotor cortex (PM) of two Japanese monkeys (Macaca fuscata), while they were performing a motor task that required wrist flexion or extension to a target. The correct movement was instructed by either 1) a conditional color cue [green or red light emitting diodes (LED)] equidistant from the targets or 2) a directional cue toward extension or flexion (right or left LED). When the green or right LED was illuminated, extension was to be performed. When the red or left LED was illuminated, flexion was required. The movement was triggered by a visual stimulus either simultaneously with the instruction stimulus or after a variable delay. 2. Before drug injection, single-unit recordings were made to select injection sites 1) in the dorsal aspect of t...