Effect of the short-term magnetic stimulation by rTMS on P300 latency

The purpose of this study is to investigate the effect of P300 latency in case of magnetic stimulation to human brain by rTMS. This stimulation is 100 pulses with 1 Hz or 0.5 Hz low-frequency. The stimulation points are left-right SMG and left-right DLPFC. In case of 1 Hz magnetic stimulation to left SMG, P300 latency after the magnetic stimulation was shorter than P300 latency before the magnetic stimulation. In case of 1 Hz low-frequency magnetic stimulation to left DLPFC, P300 latency after the magnetic stimulation was later than before the magnetic stimulation. In case of 0.5 Hz low-frequency magnetic stimulation to left SMG, the delay of P300 latency was observed. Generally, in the low-frequency magnetic stimulation equal to or less than 1 Hz, the brain activity is inhibited by stimulating the brain. The activity of left SMG is excited at 1 Hz and inhibited at 0.5 Hz. As this reason, at first, in this study, the frequency of the magnetic stimulation is just 1 Hz and this frequency is border of low-frequency and high-frequency. Secondarily, the sensitivity for the magnetic stimulation varies by parts of brain. Therefore, this study suggests that left SMG is activated by the short-term magnetic stimulation using rTMS (1 Hz, 100 pulses).