PMC

Proportion of voxels in somatosensory areas showing sVx properties. Conventions as in .

Proportion of voxels in the inferior parietal lobule showing sVx properties. Only for left PGa (arrow) was the average number of sVx below that expected by chance. Conventions as in .

Parameter estimates for FingerExe, FootExe, and MouthExe (lower panel) relative to a passive baseline for the 13 ROIs illustrated in the upper left panel. “*” over a Foot or MouthExe bar indicates the parameter estimate is lower than FingerExe at P < 0.05, “∧” the same at P < 0.001.

Forward and inverse models of sVx. Brain areas indicated with circles filled in black are thought to contain primarily motor; areas filled in white, sensory; and areas filled in white-to-black gradient, intermediate representations. The table within the figure details the function of the main nodes during execution and observation. See text for details.

Relative contribution to the total number of sVx in the brain. Areas OP2–3 and PFm are omitted because they contained less than 5 sVx. The pie represents the total average number of sVx in the brain and each slice the proportion of total sVx contributed by a particular area (left and right hemisphere combined).

Brain activity for 3 randomly selected single subjects. Activations are shown on 12 axial slices taken at 8-mm steps to range from z = −11 to z = 77, as shown on the sagittal section at the bottom of the figure. Sections are taken from the average T₁ image of all 16 participants. Green voxels represent voxels where the contrast Hca-Hst&Hca-Hm was significant. Red voxels, those where the execution of hand actions using the right or the left hand was significant, but where the sight of scrambled images did not produce significant activations. Yellow voxels are those where both conditions are met.

Consistency of sVx rendered on the average T₁ image of all 16 subjects. Left and middle columns show the number of subjects showing sVx properties in each voxel using unsmoothed and smoothed data respectively. Only voxels where at least 3 subjects showed sVx are shown (P < 0.025, Bonferroni corrected, see “probabilistic considerations” in Materials and Methods). Note that the color bars of the left and middle panels differ in upper bound to maximize the chromatic range within each panel. The right column shows the t-values of a traditional random effect analysis using smoothed data as in ().

Percentage of premotor and motor areas showing sVx properties. Each black diamond represents the value of a single subject in the left hemisphere, each gray one that in the right hemisphere. Open circles represent the average percentage and error bars, the standard error of the mean (SEM) over the 16 subjects. Stars over square brackets represent significant differences in the percentage of the areas showing sVx if the right and left hemisphere are compared using a Fisher's Least Significant Difference planned comparisons tests (*P < 0.05, **P < 0.001). For all areas, the average number of sVx exceeds the number expected by chance (P < 0.001 uncorrected for the number of ROIs). The dotted line indicates for each area how much sVx would be expected for single subjects by chance, and subjects above this line therefore show more sVx than expected by chance at P < 0.001 uncorrected for number of ROIs and Subjects). The table below the graph indicates for each area: hemisphere, name, size, number of subjects with significant number of sVx (P < 0.001), average number of sVx, and percentage of voxels of this area with sVx properties averaged over the 16 subjects.