| Objective: To verify the long-term potential effect of acoustic-magnetic paired associative stimulation (AM-PAS) on peripheral motor output and, using functional near-infrared spectroscopy (fNIRS), to investigate the cortical functional connectivity (FC) alterations induced by AM-PAS. Methods: Totally, 30 healthy right-handed volunteers were recruited and randomly assigned to either the AM-PAS or intermittent theta burst stimulation (iTBS) group (n=15 each). Each participant underwent a single session of AM-PAS or iTBS targeting the left primary motor cortex (M1). Resting-state data were collected before and after the intervention. FC metrics were computed at the regional and hemispheric levels for within-group and between-group comparisons. In addition, the AM-PAS group underwent a separate intervention session during which motor evoked potentials (MEPs) were recorded at baseline and at 0, 5, 10, 15, and 20 min post-stimulation to evaluate corticospinal excitability. Results: AM-PAS produced a progressive increase in MEP amplitude, with significant enhancement relative to baseline at 15 and 20 min post-stimulation (P<0.05，0.01). In contrast to iTBS, which significantly strengthened whole-brain, interhemispheric, and interhemispheric connectivity (P<0.05，0.01), AM-PAS induced a widespread reduction in cortical connectivity (P<0.05，0.01). Between-group comparisons revealed significantly lower regional connectivity following AM-PAS than iTBS, particularly within the left hemisphere (P<0.05). Conclusion: AM-PAS effectively induces long-lasting enhancement of peripheral motor output for up to 20 min. Unlike iTBS, which promotes cortical coupling, AM-PAS triggers broad cortical desynchronization, potentially reflecting the activation of subcortical reticular circuits. These findings suggest that AM-PAS may complement existing neuromodulation techniques by engaging subcortical pathways, although its precise mechanisms warrant further investigation. |
