Quantization of continuous arm movements in humans with brain injury

Segmentation of apparently continuous movement has been reported for over a century by human movement researchers, but the existence of primitive subm ovements has never been proved. In 20 patients recovering from a single cer ebral vascular accident (stroke), we identified the apparent submovements t hat composed a continuous arm motion in an unloaded task. Kinematic analysi s demonstrated a submovement speed profile that was invariant across patien ts with different brain lesions and provided experimental verification of t he detailed shape of primitive submovements, The submovement shape was unaf fected by its peak speed, and to test further the invariance of shape with speed, we analyzed movement behavior in a patient with myoclonus. This pati ent occasionally made involuntary shock-like arm movements, which occurred near the maximum capacity of the neuromuscular system, exhibited speed prof iles that were comparable to those identified in stroke patients, and were also independent of speed.