FIGURE 4.

Context-dependent changes in muscle activity. Mean EMG for extensor (A) and flexor (B) muscles in the different tapping conditions aligned on time of tap. Shaded area corresponds to the time-window where variability in the random task was significantly different than variability in the rhythmic task for both flexor and extensor data (-300 to -200 ms before the tap). (C,D) CVt of EMG data computed for the random and the two rhythmic conditions. (E,F) Mean CV during the test period averaged across all subjects. For both extensor and flexor muscles the CV during random conditions were significantly higher than both rhythmic conditions (Kruskal–Wallis p < 0.01). Data taken from experimental set B.