Changes in Motor Cortex Activity During Reaching Movements With Similar Hand Paths but Different Arm Postures

SUMMARY AND CONCLUSIONS gle cell activity with starting arm posture. It could signify 1. Neuronal activity was recorded in the motor cortex of a mon- processing of an extrinsic parameter, hand path in space that key that performed reaching movements with the use of two differ- varies with starting arm position, or it could reflect intrinsic ent arm postures. In the first posture (control), the monkey used parameters of the movement. Nevertheless, even though sin-its natural arm orientation, approximately in the sagittal plane. In gle cells showed a rotation of their directional tuning with the second posture (abducted), the monkey had to abduct its elbow nearly to shoulder level to grasp the handle. The path of the hand starting shoulder angle, the population vector was described between targets was Sin&U in both arm pOSh.UX%, but the joint as remaining aligned with the direction of hand movement kinematics and kinetics were different. throughout the work space 2. In both postures, the activity of single cells was often broadly The present paper reports observations on the response tuned with movement direction and static arm posture over th