Effects of high frequency repetitive transcranial magnetic stimulation on P-300 event-related potentials

Objective: Auditory event-related potentials (P-300-ERPs) were analyzed bef ore and after repetitive transcranial magnetic stimulation (rTMS). Methods: Two rTMS trains (10 Hz, 3 s, 100% motor threshold and 5 min interv al) were delivered over the left frontal area in healthy subjects. P-300-ER Ps were recorded at 14 electrode sites on the scalp using a typical oddball paradigm before and after rTMS. The latencies and amplitudes of N-100, P-2 00, N-200(X) and P-300 were measured and compared. The directed coherence ( DCOH) was estimated to demonstrate information Row between different cortic al areas. Results: rTMS significantly influenced P-300-ERPs. The effects differed on the different components (P < 0.001). The latency of P-300 significantly in creased after stimulation, which was more obvious in the frontal and centra l areas. The changes in P-300 amplitude were not significant (P > 0.05). Th e DCOH from the frontal. central, parietal and occipital areas to the tempo ral area was significantly higher than the DCOH from the temporal area to t he former 4 areas (P < 0.01). Conclusions: rTMS with the present parameters can affect P-300-ERPs, leadin g to a delayed P-300 component and changes in information connections aroun d the stimulated site. Our data suggest that rTMS may postpone neuronal act ivities related to cognitive processing. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.