Anatomy & Physiology: Current Research
Open Access

Abstract

Effects of Mental Fatigue on Brain Activity and Cognitive Performance: A Magnetoencephalography Study

Masaaki Tanaka, Akira Ishii, Yasuyoshi Watanabe

Background: Mental fatigue is prevalent in modern society. Since mental fatigue causes cognitive impairment and this has been one of the most significant causes of accidents, it is important to understand the neural mechanisms of mental fatigue related to cognitive performance and to develop appropriate methods for evaluating and overcoming mental fatigue. In this study, we quantified the effect of mental fatigue on neural activity and cognitive performance and evaluated the relationship between the change of brain activity and cognitive impairment induced by mental fatigue using magnetoencephalography.

Methods: Thirteen healthy male volunteers participated in this study. They performed mental fatigue-inducing task trials for 30 min. resting state magnetoencephalography measurements and cognitive tasks were performed before and after the fatigue-inducing task. Magnetoencephalography data were analyzed using narrow-band adaptive spatial filtering methods.

Results: Alpha-frequency band (8-13 Hz) power in the visual cortex decreased after performing the mental fatigue-inducing task. The decreased level in the alpha-frequency band power was positively associated with the impaired cognitive task performance.

Conclusions: These results demonstrate that performing the mental fatigue-inducing task causes over-activation of the visual cortex, manifested as the decreased alpha-frequency band power in this brain region, and the over-activation was associated with the cognitive impairment. Our results increase understanding of the neural mechanisms of mental fatigue and these may be utilized to develop new quantitative methods to assess mental fatigue.