Effect of mental fatigue on the central nervous system: an electroencephalography study

Abstract

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.

Transcranial photobiomodulation with infrared laser increases power of brain oscillations

“…transcranial direct current stimulation (tDCS) and transcranial magnetic stimulation (TMS)) to study the mechanisms of neuromodulation techniques (22)(23)(24). Modulation in the activity of alpha (8)(9)(10)(11)(12)(13), beta (13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30), and gamma (30-70 Hz) rhythms have long been associated with cognitive function and brain states (25)(26)(27). Moreover, a variety of forms of tPBM (using either LEDs at wavelengths between 800-850 nm or a laser at 1064 nm) have been reported to enhance human cognitive functions, such as working memory, sustained attention, category learning and executive skills (8,(10)(11)(12)(13)(14)(15)28).…”

Two types of mental fatigue affect spontaneous oscillatory brain activities in different ways

“…Each frequency band is associated with specific information processing in the central nervous system [13]. Recently, we found that two types of mental fatigue affected spontaneous EEG alpha and beta power densities in different way [14]: After enrollment, 18 participants 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.…”

Effect of Mental Fatigue on Error Monitoring

“…In a mental-fatigue-inducing task session, participants performed 100 minutes of 2-back test trials [28], which could not be performed without using working memory. The 2-back test procedure is shown in Figure 1.…”