Figure 5 : Mean and standard deviation of the interactions between Condition and Time factors for in the ANOVAs on each component. *p<0.5 **p>0.01
Figure 6 shows the results of the differential waves that highlight the left parietal contribution in the reaching preparation and the bilateral medial parieto-occipital contribution of the stepping preparation. Figure 6a shows the scalp topography of the voltage distribution from a posterior point of view in the -1500/0 ms interval of theReaching minus Keypress difference wave (left) and of theReaching-Stepping minus Reaching difference wave. Figure 6b shows, for the same difference wave and interval, the source reconstruction of those ERP activities. Source analysis for the Reaching minus Keypress difference show that the activity was localized almost exclusively in the left hemisphere, which is the hemisphere contralateral to the right arm/hand used to perform the task. In addition, it suggests that this reaching-related activity mainly originates latero-posteriorly (from the middle occipital gyrus, the inferior occipital sulcus, the intraparietal-transverse occipital gyrus, the inferior parietal lobule, IPL) and dorsally up to the anterior precuneus but not medially. Source analysis for theReaching-Stepping minus Reaching difference show that the activity was mainly bilateral and that the stepping-related activity originates in the IPL and in the PPC, both medially and dorsally up to the anterior precuneus. In addition, ERP activity may originate also latero-posteriorly from the middle occipital gyrus but mainly in the right hemisphere.