Motor cortical muscimol injection disrupts forelimb movement in freely moving monkeys.

To investigate how GABAA inhibition in the motor cortex is involved in motor control in freely moving infant macaque monkeys, muscimol, a GABAA agonist, was injected into the hand motor area and changes in movement parameters of visual reaching during apple pickup tests or a delayed response task were examined. After the injection (30 micrograms microliters-1) the monkeys tended to use the contralateral hand, and the ipsilateral hand showed a posture of dropped wrist and fingers, as if the radial nerve were paralysed. Movement time and/or reaction time of the ipsilateral hand was prolonged. Motorcortical GABAA inhibition is important for initiation of smooth flexion and/or extension movement of the hand and fingers.