Understanding the effects of different transcranial magnetic stimulation control protocols: a behavioral and neural perspective

Transcranial magnetic stimulation (TMS) is a noninvasive stimulation technique for modulating brain activity. However, selecting optimal control protocols to account for their neural and non-neural effects remains a challenge. To this end, the present event-related potential (ERP) study investigated the behavioral and neural effects of three commonly used control protocols, namely, sham stimulation and real stimulation with continuous theta burst stimulation (c-TBS) over the vertex and primary visual cortex (V1), on a given task manipulating pitch in voice auditory feedback. The results showed no significant differences in vocal and ERP responses to pitch perturbations among the three TMS control protocols, suggesting their comparable neural and non-neural influences on vocal feedback control. Compared with the baseline condition (no TMS), all three TMS control protocols led to intact vocal compensations but prolonged N1 latencies and reduced P2 amplitudes, potentially linked to nonspecific stimulation effects or placebo-like responses. These findings provide the first neurobehavioral evidence for comparable effects across different TMS control protocols on vocal pitch regulation, offering insights for selecting optimal control strategies to explore the causal mechanisms of auditory-vocal integration. They also emphasize the importance of including a baseline condition to disentangle genuine TMS effects.<b>NEW & NOTEWORTHY</b> This is the first study to provide neurobehavioral evidence comparing the effects of three transcranial magnetic stimulation (TMS) control protocols on vocal feedback control. The findings suggest that sham stimulation and real stimulation [continuous theta burst stimulation (c-TBS) over vertex and V1] produce similar neural and non-neural effects on vocal pitch regulation. Despite no differences in vocal responses, all protocols led to prolonged N1 latencies and reduced P2 amplitudes, emphasizing the importance of including a baseline condition to isolate genuine TMS effects.