Figure 1.

Preliminary results that guided the design of the finger mapping protocol. A, Comparable somatotopic representation in the contralateral S1 to unilateral and bilateral finger stimulation, at within-subject level. The map of the fingertips (d2–d5) in contralateral S1 was strikingly similar in a condition in which we stimulated the fingertips of one hand at time and in another condition whereby we stroked homologous fingertips of both hands simultaneously. B, Bootstrapping validation. We validated the results shown in A using a bootstrapping approach. Seven functional runs per condition (unilateral stimulation, bilateral stimulation) were collected in a single participant, in multiple scanning sessions. We selected, both recursively and randomly, 4 runs among the 7 collected per condition and averaged results across these 4 runs to assess intraindividual map reproducibility. The maps of the fingertips were highly reproducible in both unilateral and bilateral stimulation conditions. C, Time course of activity in the left hemisphere during unilateral fingertip stimulation. Percent modulation of BOLD response in the left S1 induced by periodic stimulation of the fingertips of the right hand and left hand. We did not observed a spatially tuned activation of the left S1 induced by left-hand stimulation.