Effect of Mental Fatigue Induced by Repeated Continuous Calculation Tasks on Event-related Brain Potential (P300)

It is well known that the amplitude and latency of P300 in event-related brain potentials (ERPs) evoked by performing the oddball paradigm reflect the extent of individuals' selective attention. The purpose of this study was to examine whether P300 is a reliable measure for evaluating mental fatigue. In addition to the measurement of auditory ERPs derived from Fz, Cz and Pz, the concentrations of lactic acid, cortisol in plasma and the reaction time of the oddball paradigm, which are believed to reflect fatigue, were measured. In an attempt to cause mental fatigue, 12 healthy college students (8 males, 4 females; 19.5 ± 0.5 yr; mean ± S.D.) were forced to perform a continuous addition task using the Uchida-Kreperin test paper for about 2 h. Before the task, the latencies of P300 in Fz, Cz and Pz were 295.6 ± 8.7 msec, 298.8 ± 8.5 msec and 297.5 ± 7.2 msec (mean ± S.D.), respectively, and after the task they were 312.6 ± 11.2 msec, 314.6 ± 10.1 msec and 315.8 ± 8.7 msec, respectively. A significant difference in the latency before and after the task was detected (p