title: Effects of daily levels of fatigue and acutely induced fatigue on the visual evoked magnetic response.
abstract: Fatigue is a common complaint in modern society. As photosensitivity is associated with fatigue, this study aimed to clarify the relationship between neural response to visual stimuli and fatigue using a 160-channel whole-head-type magnetoencephalographic system. Twelve healthy male volunteers were enrolled. Participants were randomly assigned to two groups in a single-blinded, crossover fashion to perform acute fatigue-inducing mental task sessions, i.e., 0-back or 2-back test for 30 min. Visual evoked magnetic field (VEF) intensities were evaluated by standardized low-resolution brain electromagnetic tomography modified for a quantifiable method. VEF consisted of two phases, and although acute fatigue did not alter the VEF intensities and the intensities before the acute fatigue-inducing mental task sessions were not correlated with the Chalder's Fatigue Scale scores in either of the two phases, the intensities after the 0-back test trials for 30 min in Phase 1 and those after the 2-back test trials in Phase 2 were significantly correlated with the fatigue scale scores. The daily level of fatigue was related to VEF intensity after the acute mental fatigue loads. Our findings provide new perspectives to evaluate our daily level of fatigue as well as to clarify the neural mechanisms underlying it.
authors.affiliation: Department of Physiology, Osaka City University Graduate School of Medicine, 1-4-3 Asahimachi, Osaka 545-8585, Japan.
authors.forename: Yoshihito
authors.initials: Y
authors.lastname: Shigihara
authors.forename: Masaaki
authors.initials: M
authors.lastname: Tanaka
authors.forename: Kei
authors.initials: K
authors.lastname: Mizuno
authors.forename: Akira
authors.initials: A
authors.lastname: Ishii
authors.forename: Emi
authors.initials: E
authors.lastname: Yamano
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; D000704:Analysis of Variance; D001921:Brain / Q000503:physiopathology*; D001931:Brain Mapping; D018592:Cross-Over Studies; D005074:Evoked Potentials, Visual / Q000502:physiology*; D006801:Humans; D008280:Magnetics; D015225:Magnetoencephalography; D008297:Male; D005222:Mental Fatigue / Q000209:etiology / Q000503:physiopathology*; D009483:Neuropsychological Tests; D010147:Pain Measurement; D010775:Photic Stimulation; D011569:Psychiatric Status Rating Scales; D016037:Single-Blind Method; D055815:Young Adult