Descending corticospinal control of intersegmental dynamics.

摘要: To make an accurate movement, the CNS has to overcome inherent complexities of multijoint limb. For example, interaction torques arise when motion individual arm segments propagates adjacent causing their movement without any muscle contractions. Since these passive joint significantly add overall generated by active muscular contractions, they must be taken into account during planning or execution goal-directed movements. We investigated role corticospinal tract in compensating for movements humans. Twelve subjects reached visual targets with supported a robotic exoskeleton. Reaching one target was accompanied that assisted while reaching other resisted movement. Corticospinal excitability assessed at different times using single-pulse transcranial magnetic stimulation (TMS) over upper-arm region M1 (primary motor cortex). found TMS responses shoulder monoarticular and elbow–shoulder biarticular muscles changed together which were resistive. In contrast, did not correlate assistive co-contraction. This suggests descending command includes compensation limb dynamics. Furthermore, our results suggest involves muscles, span both elbow joints are biomechanically advantageous position provide such compensation.