title: Central nervous system fatigue alters autonomic nerve activity.
abstract: OBJECTIVE
  Fatigue is a common symptom in modern society. In order to clarify the mechanisms underlying fatigue, we examined the association between central nervous system fatigue and autonomic nerve activity.
  
  
  METHODS
  The study group consisted of 20 healthy subjects. They performed the 2-back test for 30 min to induce fatigue. Just before and after the fatigue-inducing session, they completed the advanced trail making test (ATMT) for 30 min as a fatigue-evaluating task session. In order to measure autonomic nerve activity, electrocardiograms were monitored continuously throughout the experiment.
  
  
  RESULTS
  After the fatigue-inducing task session, impaired task performance was demonstrated based on the total trial number and error counts of the ATMT. During the task session, although task performance as measured using the accuracy and the mean reaction time of the 2-back test was almost unchanged, electrocardiographic R-R wave interval analyses showed a decreased high-frequency component power and an increasing trend in the low-frequency component power/high-frequency component power ratio.
  
  
  CONCLUSIONS
  Decreased vagal nerve activity and increased sympathetic nerve activity are associated with central nervous system fatigue.
authors.affiliation: Department of Physiology, Osaka City University Graduate School of Medicine, 1-4-3 Asahimachi, Abeno-ku, Osaka City, Osaka 545-8585, Japan. masa-t@msic.med.osaka-cu.ac.jp
authors.forename: Masaaki
authors.initials: M
authors.lastname: Tanaka
authors.forename: Kei
authors.initials: K
authors.lastname: Mizuno
authors.forename: Seiki
authors.initials: S
authors.lastname: Tajima
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Sasabe
authors.forename: Yasuyoshi
authors.initials: Y
authors.lastname: Watanabe
mesh_terms: D000328:Adult; D017776:Autonomic Pathways / Q000503:physiopathology*; D001921:Brain / Q000502:physiology*; D005221:Fatigue / Q000503:physiopathology*; D006801:Humans; D008297:Male; D013647:Task Performance and Analysis