Figure 6.

α-MN activity (on the output scale of [0, 1]) and corresponding muscle torques for movements W_A and R_A. Solid traces correspond to the flexor and dashed lines to the extensor muscle in each joint. Filled gray areas indicate net muscle torques (i.e., the sum of flexor and extensor). In whipping movements, where interaction torques oppose the motion, muscle activity is generally larger than in reaching movements, even though in both cases absolute joint excursions are the same. During reaching movements muscle activity is smaller. Note in particular the absence of a braking pulse in the elbow. Elbow deceleration in this case is almost exclusively due to interactions torques produced by the shoulder.