Background: Repetitive transcranial magnetic stimulation (rTMS) and event-related potentials (ERPs) are a noninvasive technique that widely used in neurophysiological field. Although rTMS has shown clinical utility for a number of neurological conditions, Recently,there was little understanding of the the efficacy of rTMS on Schizophrenia(SZ) and the change of ERP between before and after rTMS treatment. The objective of this study was to investigate the characteristics of N400, mismatch negativity (MMN), and P300 before and after treatment with rTMS in SZ.
Methods: One hundred and twenty-seven SZ patients hospitalized in Shanghai Mental Health Center from March 2015 to July 2017, divided into two groups (85 patients were recruited as rTMS group and 42 were recruited as sham rTMS [ShrTMS] group) and 76 normal controls (NCs) who were the staff and refresher staff in our hospital were recruited at the same time. A Chinese-made rTMS and a Runjie WJ-1 ERPs instrument were used in the present experiment. N400 was elicited by congruent and noncongruent Chinese idioms. After rTMS treatment, N400, P300, and MMN characteristics were compared with those before treatment and NC group.
Results: Compared with NC, the SZ patients exhibited delays in N400, P300, and MMN latency and decreased N400, P300, and MMN amplitudes in their frontal area (P < 0.05). After 25 rTMS treatments, N400 amplitudes in the frontal area (elicited by idioms with same phonic and different shape and meaning and with different phonic, shape, and meaning) were increased in the SZ patients (P < 0.05). However, there was no significant change in N400 before and after treatment with ShrTMS in SZ patients (P > 0.05). Amplitudes for MMN and target P300 also increased in SZ patients after rTMS treatment (P < 0.05).
Conclusions: Based on our preliminary findings, we believe that the combined usage of N400, MMN, and P300 could be a valuable index and an electrophysiological reference in evaluating the effects of rTMS treatment in SZ patients.