Figure 4 : Scalp topography (top-flat view) of the three conditions in the -1500/-750 ms and -750/0 ms intervals.
The ANOVA on the Prefrontal pool showed a significant effect of Condition, Time, and their interaction. Post-hoc comparisons indicate that the pN amplitude in the Keypress condition, for both time intervals, was larger (p<0.001) than in the Reachingand Reaching-Stepping conditions, which did not differ from each other. ANOVA on the Central pool showed a significant effect of Condition, Time, and their interaction. Post-hoc comparisons indicate that the early BP amplitude did not change among the three conditions, but in the late interval, all the conditions were significantly different (p<0.01) with the largest amplitude for the Keypress condition, lowest for the Reaching-Stepping , and intermediate for the Reaching condition. ANOVA on the Parietal pool showed a significant effect of Time and of the interaction. Post-hoc comparisons indicate that the early pBP amplitude did not change among the three conditions, but in the late interval, theReaching condition showed larger amplitudes (p=0.004) than the other two that did not differ from each other. ANOVA on the Occipital pool showed a significant effect of Condition, Time, and their interaction. Post-hoc comparisons indicate that the vN amplitude in theReaching-Stepping condition, for the early interval, was larger (p=0.002) than in the Reaching and Keypress conditions, which did not differ from each other. In the late interval, theReaching-Stepping condition amplitude was larger than the Keypress condition (p=0.023). Table 1 shows the statistical data and Figure 5 the mean amplitudes of the interactions.