Transcranial magnetic stimulation (TMS) is a non-invasive 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 to 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.
Keywords: continuous theta burst stimulation; control condition; placebo effects; transcranial magnetic stimulation; vocal motor control.