Fig. 6.

Changes in individuation in a single session.A, B, Plots of normalized finger positions (0, position at extension switch closure;100, position at flexion switch closure) from two successful trials of instructed movement 1f, one performed before (A) and the other after (B) the muscimol injection in session 15. In these two panels, the normalized position of each digit and of the wrist has been plotted as a function of the simultaneous normalized position of the instructed digit, digit 1. Whereas the noninstructed digits did not move as the monkey flexed his thumb before the muscimol injection (A), digits 2 and 4 extended as the monkey flexed his thumb after the injection (B).C, Relative motion coefficients (ordinate) derived from the slopes of such plots for each digit in each correctly performed trial of 1f in session 15. The single trials shown in A and B are indicated here by arrowheads. After the muscimol injection (bar at bottom), coefficients for noninstructed digits diverged from their near-zero baselines.D, Individuation Index calculated from these coefficients for each successful 1f trial. E, Individuation Index for trials of 4e in the same session. The Individuation Index of 1f trials decreased progressively after the muscimol injection, whereas the Individuation Index for 4e trials remained stable. The total elapsed time in session 15 was 100 min (injection, 8 min).