359728.fig.002a
(a)
359728.fig.002b
(b)
Figure 2: Mechanism of motor function change after noninvasive brain stimulation (NIBS) in stroke patients. (a) Inhibitory NIBS over the unaffected hemisphere. Inhibitory NIBS decreases excitability of the contralesional motor cortex (M1) and increases excitability of the ipsilesional M1 by reducing interhemispheric inhibition from the unaffected to the affected hemisphere. Facilitation of the ipsilesional M1 improves motor function of the paretic hand in stroke patients. However, the antiphase bimanual movement deteriorates owing to the reduction of interhemispheric inhibition, which controls bimanual movement. (b) Bilateral NIBS. Excitatory NIBS along with inhibitory NIBS also decreases excitability of the contralesional M1, increases excitability of the ipsilesional M1, and improves motor function of the paretic hand in stroke patients. Bilateral NIBS lessens the reduction of interhemispheric inhibition induced by inhibitory NIBS and prevents deterioration of antiphase bimanual movement. Modified from Takeuchi et al. [88].