Figure 1.

Experimental design including mRT Task and diffusion tensor imaging. The temporal order of random blocks of finger opposition movements performed with the right and then left hand is shown. For the right hand, nonspecific learning was calculated as the difference in RT between the random blocks R2 and R4 (dotted lines). The amount of nonspecific transfer from the right to the left hand was calculated as the difference in RT between the random blocks R2 and L2 (dashed lines). The subdivision of CC into five subregions (CC1–CC5) is displayed on the pictured brains. RT (response time) and FA (fractional anisotropy) indicate respectively the measures of motor performance and callosal damage in the five callosal subregions connecting the two hemispheres. Right hand is the “Learning Hand” and left hand is the “Transfer Hand”, controlled respectively by the learning and the transfer hemispheres.