Distinct modulation of interhemispheric inhibitory mechanisms during movement preparation reveals the influence of cognition on action control

The supplementary motor area modulates interhemispheric interactions during movement preparation

“…Using TMS, we showed that PMd right -M1 left and SMA right -M1 left interactions remained unchanged after right SMA disruption. This is consistent with a previous study showing that changes in IHI occurred independently of changes in corticospinal tract excitability (measured with single pulse TMS) during the premovement phase(Hinder et al, 2017). Most studies that have investigated the role of IHI during movement preparation focused on the premovement phase, and the processes at stake during the delay period remain elusive.…”

“…In our study, the fact that we assessed the PMd-M1 interaction directed toward the dominant hemisphere during the preparation of dominant hand movements may explain this discrepancy. A recent study (published after the beginning of our experiments) reported significant M1 inhibition following contralateral SMA stimulation at longer ISI (40 ms) (Fiori et al, 2017 Hinder et al, 2017;Liuzzi et al, 2010;Murase et al, 2004). It is thus possible that the lack of effect of PMd stimulation during movement preparation was due to the stimulation of different PMd subregions in the different subjects during our experiments.…”

“…The level of inhibition did not depend on whether hand coordination was required or not (unimanual or bimanual). Later, during the premovement phase preceding unimanual movements, the IHI directed toward the active M1 (contralateral to the moving hand) is progressively lifted and turns into facilitation, while the IHI toward the ipsilateral M1 remains constant (Duque, Hummel et al, 2005;Duque et al, 2007;Hinder et al, 2017;Liuzzi et al, 2010;Murase et al, 2004). During the delay period the amplitude of the IHI toward the active hemisphere is modulated by the skillfulness required for the forthcoming unimanual tasks (Wischnewski et al, 2016).…”

“…Several interconnected cortical areas may influence interhemispheric interactions during the execution of coordinated bimanual movements like the primary motor cortex (M1), dorsal premotor cortex (PMd) as well as the cingulate motor area and posterior parietal cortex (Koeneke, Lutz, Wüstenberg, & Jäncke, 2004;Swinnen, 2002). Many studies focusing on the premovement phase have demonstrated the critical role of interhemispheric inhibition (IHI) and interhemispheric facilitation between the two M1 and between the PMd and the contralateral M1 (Chen & Hallett, 1999;Duque, Hummel et al, 2005;Duque et al, 2007;Hinder et al, 2017;Koch et al, 2006;Kroeger et al, 2010;Leocani, Cohen, Wassermann, Ikoma, & Hallett, 2000;Liuzzi et al, 2010;Murase, Duque, Mazzocchio, & Cohen, 2004;O'Shea, Sebastian, Boorman, Johansen-Berg, & Rushworth, 2007). Motor preparation is broadly defined as the period preceding movement onset and refers to the different steps from decision-making to movement execution (Bestmann & Duque, 2016;Svoboda & Li, 2018).…”

“…The "delay period" is the interval between the two cues, during which the subject prepares the movement while remaining immobile, and the "premovement phase" per se is comprised between the instruction to move and movement onset. Many studies focusing on the premovement phase have demonstrated the critical role of interhemispheric inhibition (IHI) and interhemispheric facilitation between the two M1 and between the PMd and the contralateral M1 (Chen & Hallett, 1999;Duque, Hummel et al, 2005;Duque et al, 2007;Hinder et al, 2017;Koch et al, 2006;Kroeger et al, 2010;Leocani, Cohen, Wassermann, Ikoma, & Hallett, 2000;Liuzzi et al, 2010;Murase, Duque, Mazzocchio, & Cohen, 2004; O'Shea, Sebastian, Boorman, Johansen-Berg, . By contrast, there is little insight about the mechanisms and brain regions involved in interhemispheric interactions during the delay period.…”