Fig. 4.

Breakdown of the percentages of muscle responses by laterality for each of the cortical motor areas. M1 stimulation resulted in no ipsilateral responses (a); however, stimulation of PMd and SMA (b and c) resulted in a number of ipsilateral responses (c). More than 65 % of sites in M1 and PMd produced contralateral responses (a and b); however, only 49 % of sites in SMA produced contralateral responses (c). The graph in d shows the response laterality for each area with the number of sites showing contralateral, ipsilateral, and bilateral responses recorded above each bar. There were more ipsilateral and fewer contralateral sites found in SMA compared with M1 and PMd. For each graph, contralateral responses are represented in black, ipsilateral responses are represented in white, and bilateral responses are represented in gray