Figure 2.

(a) Tracking errors (across-subjects, mean ± SD) when subjects manipulate rotated mouse (orange line), velocity mouse (blue line), and normal mouse (black line) in training sessions. (b) Time course of errors (across-subjects, mean ± SD) in last five training sessions aligned on switching of tools. Broken line with open circles indicates time course obtained from a control experiment, in which the cursor position was reset to center but the tool did not change and was always the normal mouse. (c) Tracking errors (across-subjects, mean + SD) when cerebellar activity was scanned in the first experiment. Error during manipulation of rotated mouse or velocity mouse was matched by changing target velocity during manipulation of normal mouse (baseline). Baseline error matched to rotated mouse was significantly larger than corresponding test error [F(1, 6) = 15.52, P < 0.01]. There was no significant difference in errors between velocity mouse and corresponding baseline [F(1, 6) = 0.45]. (d) Tracking errors (across-subjects, mean + SD) in the first and the supplementary scanning experiments. There was no significant difference between any pair of mean values according to Tukey's honestly significant difference method (at P < 0.05 level).