Figure 1.

Experimental setup and main effects of the grip task. a, Left, Photograph of grip-force manipulandum. Right, Screens displayed during scanning for a grip trial (arrow shown at bottom of thermometer-like visual display) and a no-grip trial (central cross being presented instead of the arrow). During grip trials, a yellow target bar indicated the required force level, as shown in the schematic example. The actual force exerted by the affected hand was indicated by red shading of the thermometer-like display and the white arrow pointed to the paretic hand to indicate that active grip was required. Participants were instructed to generate a nonballistic force matching the displayed target bar, using a gentle pace without major corrective movements (see main text). In all trials, TMS (5 pulses, 11 Hz) was applied unpredictably to contralesional PMd at one of two intensities (110% resting motor threshold or 70% active motor threshold) 900 ms after presentation of the force target level (or cross) visual instruction. b, Hand grip-related activity, regardless of TMS. The results of the group random-effects analysis are projected onto the rendered averaged structural scans from all patients. The height threshold was set at t > 3.5, uncorrected for multiple comparisons across whole brain, and the extent (or cluster) threshold set at p < 0.05, corrected for multiple comparisons across the whole brain. AH, Affected hemisphere.