Sequence, time, or state representation: how does the motor control system adapt to variable environments?

摘要: Does the observation of well-timed movements imply existence some internal representation time, such as a hypothetical neural clock? Here we report results experiments designed to investigate whether subjects form correct adaptive mechanical environments that change in very predictable manner. In these experiments, were asked execute arm over two-dimensional workspace while experiencing time-dependent disturbing forces. We provide formal definition for time and conclude our didn't use motor adaptation under tested conditions. Subjects performed arm-reaching following experiments: (1) six sinusoidal time-varying force field; (2) simple sequence alternating viscous fields, which number targets allowed approximation by complex state-dependent (3) same no field was possible. found did not adapt unable an adequate fields. latter case, whenever possible, they adapted single produced forces similar two This applied fields only trajectories executed during training phase. However, inadequate produce generated new set trajectories. These are consistent with hypothesis would develop forces, at least circumstances. speculate system responsible external may be employ temporal representation. While it is possible emerge more prolonged and/or intense training, findings indicate preference generalize based on representing dependence upon state rather than time.