Grant: Project Grant

When our arm is perturbed by an external force or obstacle during a movement, the brain possesses neural circuits that rapidly detect the error and make a corrective adjustment to complete the movement as intended. This is called feedback control. If the same perturbation occurs repeatedly, the brain gradually learns to anticipate the effect of the perturbation and adjusts the motor command for the next movement to reduce its effect. This is called predictive feedforward control. Similarly, when we try to learn a new motor skill, we make many mistakes at first but gradually reduce our errors as our skill improves. Motor control theory had long proposed that the errors sensed by feedback circuits were used to "teach" the feedforward neural circuits that plan and execute movements what to learn and how, but the feedback circuits did not change. As the feedforward circuits changed, errors decreased and the motor system increasingly functioned in feedforward mode. However, a recent study found that both feedback and feedforward circuits change while subjects learn to compensate for external force fields; they collaborate as partners during both motor learning and skilled performance, rather than only as teacher and student. This project studies the neural mechanisms in motor cortical areas of non-human primates that play a key role in detecting and correcting errors while learning a new skill, and cause adaptive changes both in the feedback and feedforward circuits to permit skilled motor performance. A better understanding of how the cortical motor system learns new skills will help in the development of new rehabilitation procedures for patients with motor control deficits. It will also lead to improved design of neuroprosthetic controllers that use neural signals about desired movements recorded in the brains of paralyzed patients to control robotic devices, thereby greatly improving their independence and quality of life.