Pre-Supplementary Motor Area Theta Burst Stimulation Alters Corticomotor Facilitation and Action Reinitiation Without Impairing Response Inhibition
Listed in
This article is not in any list yet, why not save it to one of your lists.Abstract
Background
The pre-supplementary motor area (preSMA) is increasingly being explored as a neuromodulation target for impulsive behaviour in several clinical populations. Treatment effects are generally interpreted as improvements in inhibitory control. However, healthy studies report improved/impaired/unchanged inhibitory control following identical preSMA stimulation protocols, and few studies examine accompanying neurophysiological changes. We therefore investigated whether preSMA stimulation influences downstream corticomotor excitability to modify a general stopping mechanism, other components of action control, or wider cue-dependent attentional processes relevant to impulsive behaviour.
Methods
In a preregistered, double-blind crossover study, 18 healthy adults received active and sham continuous theta burst stimulation (cTBS) over right preSMA. Motor-evoked potentials (MEPs), anticipatory response inhibition task measures, and alcohol dot-probe reaction times were collected before and after stimulation and analysed with linear mixed models.
Results
MEPs increased during sham (p = .028) but not after active cTBS (p = .741). Active cTBS did not affect complete or partial stopping on the response inhibition task. Instead, active cTBS slowed the continuing response after partial stopping (p < .001) whereas response execution sped up across the sham session (p < .001). No alcohol attentional bias or stimulation effect was detected.
Conclusions
PreSMA cTBS did not impair general inhibitory or attentional control. Instead, it attenuated session-related corticomotor facilitation and selectively slowed reinitiation of a partially inhibited action. These findings suggest that clinical effects to impulsive behaviour from preSMA neuromodulation are primarily rooted in changes to motor preparation and action updating rather than a unitary stopping mechanism.
