Fig. 7.

Evolving multijoint sensitivity of the posterior deltoid response. A: moment-by-moment statistical discrimination of the shoulder extensor's activity occurring with the shoulder flexor torque and elbow extensor torque conditions of experiment 1; data from the group of normal subjects. If its muscle activity is only linked to shoulder motion then discrimination between these 2 conditions will be at chance levels, 0.5. Instead, a multijoint response would lead to discrimination greater than chance; perfect discrimination occurs at 1.0. Individual and group average receiver-operator characteristic (ROC) curves are depicted by thin gray lines and thick black lines, respectively. White dot and value indicate the time when the average ROC passes threshold (>3 SD). B: ROC curves from the group of cerebellar-damaged subjects in experiment 1. Same format as in A. C: mean ROC curves from the normal group (thick line) and the cerebellar-damaged group (thin line). Difference in the threshold time (Δ) of the 2 groups is also indicated. D–F: moment-by-moment discrimination of muscle activity occurring with combined flexion torque and combined extension torque conditions in experiment 2; same format as A–C.