Frequency Dependence of P300 Latency by Low-Frequency Repetitive Transcranial Magnetic Stimulation.

The aim of this study was to investigate the effects of repetitive transcranial magnetic stimulation (rTMS) on brain activity. The latency of the P300 component of the event-related potential (ERP) was used to evaluate the effects of low-frequency and short-term rTMS on brain activity. We investigated the effects of rTMS on P300 latencies by stimulating the supramarginal gyrus (SMG), which is considered to be the area of origin of the P300. As the frequency-dependence of low-frequency rTMS has not been previously investigated in detail, we evaluated the effects of rTMS at frequencies of 1, 0.75 or 0.5 Hz on P300 latencies. The odd-ball task was used to elicit P300s before and shortly after the scalp was stimulated by rTMS. Electroencephalography recordings were measured at the Fz, Cz and Pz electrodes, which were based on the international 10–20 electrode system. We found that 1, 0.75 and 0.5 Hz rTMS affected P300 latencies. 1 Hz rTMS of the left SMG shortened P300 latencies by approximately 25 ms at the Cz compared with the P300 latencies before rTMS. 0.5 Hz rTMS of the left SMG lengthened P300 latencies by approximately 20 ms at the Cz compared with the P300 latencies before rTMS. In contrast, 0.75 Hz rTMS of the left SMG did not affect P300 latencies. These results demonstrate that P300 latencies vary according to the frequency of rTMS. [ABSTRACT FROM AUTHOR]

Copyright of IEEE Transactions on Magnetics is the property of IEEE and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)