title: Effect of mental fatigue on the central nervous system: an electroencephalography study.
abstract: BACKGROUND
  Fatigue 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.
  
  
  METHODS
  After 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.
  
  
  RESULTS
  In 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.
  
  
  CONCLUSIONS
  Different 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.
authors.affiliation: Department of Physiology, Osaka City University Graduate School of Medicine, 1-4-3 Asahimachi, Abeno-ku, Osaka 545-8585, Japan. masa-t@msic.med.osaka-cu.ac.jp
authors.forename: Masaaki
authors.initials: M
authors.lastname: Tanaka
authors.forename: Yoshihito
authors.initials: Y
authors.lastname: Shigihara
authors.forename: Akira
authors.initials: A
authors.lastname: Ishii
authors.forename: Masami
authors.initials: M
authors.lastname: Funakura
authors.forename: Etsuko
authors.initials: E
authors.lastname: Kanai
authors.forename: Yasuyoshi
authors.initials: Y
authors.lastname: Watanabe
mesh_terms: D000328:Adult; D001921:Brain / Q000503:physiopathology*; D003071:Cognition / Q000502:physiology; D018592:Cross-Over Studies; D004569:Electroencephalography; D006801:Humans; D008297:Male; D005222:Mental Fatigue / Q000503:physiopathology*; D009483:Neuropsychological Tests; D016037:Single-Blind Method