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

Consistent with impulse control, CSE was initially suppressed prior to both left and right hand actions, irrespective of WS informativeness. Subsequent CSE increases occurred in the responding hand which were larger, and occurred earlier, following an informative WS. Importantly, these increases strongly predicted response times. In contrast to the generic CSE suppression, an informative WS permitted a hand-specific release of IHI10 in the responding hand, whereas IHI40 was released in both hands. As releases of IHI cannot explain a simultaneous suppression of CSE, this suggests several distinct movement preparation mechanisms are at play with IHI modulation occurring independently from impulse control. Notably, the findings support the notion that IHI10 and IHI40 between contralateral motor regions are mediated by discrete transcallosal pathways, and are differently modulated by specific motor and cognitive attributes of a rapid choice task.