BackgroundFatigue can be classified as mental and physical depending on its cause, and each
type of fatigue has a multi-factorial nature. We examined the effect of mental
fatigue on the central nervous system using electroencephalography (EEG) in eighteen
healthy male volunteers.MethodsAfter enrollment, subjects were randomly assigned to two groups in a single-blinded,
crossover fashion to perform two types of mental fatigue-inducing experiments. Each
experiment consisted of four 30-min fatigue-inducing 0- or 2-back test sessions and
two evaluation sessions performed just before and after the fatigue-inducing
sessions. During the evaluation session, the participants were assessed using EEG.
Eleven electrodes were attached to the head skin, from positions F3, Fz, F4, C3, Cz,
C4, P3, Pz, P4, O1, and O2.ResultsIn the 2-back test, the beta power density on the Pz electrode and the alpha power
densities on the P3 and O2 electrodes were decreased, and the theta power density on
the Cz electrode was increased after the fatigue-inducing mental task sessions. In
the 0-back test, no electrodes were altered after the fatigue-inducing sessions.ConclusionsDifferent types of mental fatigue produced different kinds of alterations of the
spontaneous EEG variables. Our findings provide new perspectives on the neural
mechanisms underlying mental fatigue.