Significant activation in imitation task, in control subjects (A–F), as obtained from multisubjects analysis, and in three callosotomized patients (G–I). (A,D) OBSERVE condition: activation of anterior left supplementary motor area (SMA; A, yellow arrows) is evident. z values in (A,D) are 53 and 6, respectively. (B,E) IMAGE TO IMITATE condition: activation of anterior (B, yellow arrow) and posterior left SMA (B, red arrow) is shown. Bilateral activation in IFG (area 44; (E), green arrows) and opercular cortex (E, blue arrows) is also visible. z values in (B,D) are 55 and 6, respectively. (C,F) IMAGE TO IMITATE>OBSERVE: only the activation in left posterior SMA (C, red arrow), left IFG (F, green arrow), and bilateral parietal opercula (F, blue arrows) is evident. z values are 57 and 6, in (C,F), respectively. (G–I) IMAGE TO IMITATE condition in three patients: in (G) (total callosotomy) and (I) (anterior callosotomy) bilateral activation foci in opercular cortex are evident (blue arrows); in (H) (total callosotomy) in left hemisphere only. Axial images in (H,I) are from the same z values; in (G), the two hemispheres are from different z values because of different position of the opercular activation foci. CS, central sulcus; SS, Sylvian sulcus; according to the radiological convention, the left hemisphere is shown on the right. Modified from Pierpaoli et al. (2020a,2021a).