The proposed research will provide data on the different contributions of motor, premotor and posterior parietal cortex to the control of complex movements. Electrical microstimulation with long (~ half-second) trains of current pulses delivered via microelectrode to these regions of the cortex evokes complex reaching, grasping, and defensive movements in monkeys and other primates. It has been hypothesized that neurons involved in distinct behaviors are located in separate zones within the frontal and posterior parietal regions and they form series of specialized parieto-frontal circuits. To study the specificity of motor, premotor, and posterior parietal areas and determine their roles in mediating complex motor responses, we propose a series of experiments that will combine the long train stimulation with reversible cortical deactivation. Thus, each of these areas will be partially deactivated with muscimol or lidocaine during stimulation of other areas with long trains and changes in evoked behaviors will be recorded and carefully analyzed. To produce movements similar to those made voluntarily the duration of the stimulus will match the time course of the behavior being studied. Since movement patterns elicited from one area of the parieto-frontal circuit likely depend on interconnections with other areas, we expect that inactivation of the area (or areas) that mediates a specific complex behavior will alter the onset of the stimulus-triggered movements from other areas involved in this behavior. We will use New World owl monkeys that provide a good model for such studies, since their motor, premotor, and parietal areas are exposed on the surface of the brain, so stimulating electrodes can be easily placed in suitable locations. As complex motor behaviors are similar in humans and non-human primates and their motor and posterior parietal regions perform similar functions, results will help to understand human brain functions and impairments. ? ? The proposed research will provide data on the different contributions of motor-related cortical areas to the control of complex movements. Knowledge how these areas link to motor circuits will aid in our understanding of how motor behavior is achieved. As complex motor behaviors are similar in humans and non-human primates and their motor regions perform similar functions, results will help to understand human brain functions and impairments. ? ? ?
