How mental fatigue impacts brain activity?

Saturday, 31 de October de 2020
How mental fatigue might impact cognitive tasks? What the impact of mental fatigue on the human brain? How mental fatigue impacts brain activity? Neuroscience has been focused on trying to answer questions about the effects of mental fatigue phenomena in our brains. By the way, mental fatigue is a psychophysiological state which might induce a sense of tiredness, drowsiness, lack of energy, and lethargy. Normally, these phenomena appear after a prolonged mental/cognitive effort, such as driving or brain-scanning" target="_blank" rel="noopener noreferrer">reading for many hours. Beyond the psychophysiological effects aforementioned, the behavioral performance and attention capacity might be harmed for mental fatigue. For instance, soldiers got worse their reaction time, default errors, and accuracy when mentally fatigued.

Beyond the behavioral changes, neurophysiological changes have been reported during mental fatigue occurrence. As seen before, mental fatigue increases significantly the theta wave on the prefrontal cortex and worse responses of perceived effort in endurance athletes. Furthermore, an increase in alpha 1 (8-10 Hz) wave has been indicated as a signal of mental fatigue occurrence, as well as the analyzes of frontal, central, and parietal lobes. Recently, a study conducted by Li et al. compared the electrophysiological activity at the rest, during, and after a cognitive task used to induce mental fatigue. Twenty male students were recruited and did two hundred different mental arithmetic problems while their brain activity was measured in five different moments (before, during, and after cognitive task). The design of how the measures were conducted can see above.


Nineteen electroencephalogram (EEG) channels (Fp1, Fp2, F3, F4, F7, F8, Fz, T3, T4, T5, T6, C3, Cz, C4, P3, Pz, P4, O1, O2) distributed in five brain lobes (frontal, temporal, central, occipital, parietal) were used to measure brain activity. Relative values of EEG rhythms of delta (2–4  Hz), theta (4–8 Hz), alpha 1 (8–10 Hz), alpha 2 (10–13 Hz), and beta (13–30 Hz) were analyzed. The results indicated a significant change in theta, alpha 1, and alpha 2 at rest (T0) and during the mental fatigue process. Theta band increases significantly in the central lobe at rest and in the temporal lobe during the task. Alpha 1 rhythm increased significantly both in resting state and task state, in the whole brain at the rest and in the central lobe and parietal during the task. Alpha 2 rhythm decreased significantly in the resting state, but showed an increasing trend in the task state, in the whole brain on both occasions.
These results reinforce the idea that the theta and alpha band are sensitives to mental fatigue state. Moreover, the authors fortify the necessity to divide the alpha band, considering the differences in their dynamic during the experiment.

In a practical way, these results might be useful to identify mental fatigue state and then intervene to mitigate this condition. Futures studies should investigate ways the reduce the deleterious effects of mental fatigue and/or the mental fatigue itself, using strategies such as cognitive-behavioral therapy, meditation,  neurofeedback, and transcranial direct current stimulation (tDCS).
 
References:
Li et al. (2020). The impact of mental fatigue on brain activity: a comparative study both in resting state and task state using EEG. BMC Neuroscience. Doi: https://doi.org/10.1186/s12868-020-00569-1

Pires et al. (2018). Mental Fatigue Alters Cortical Activation and Psychological Responses, Impairing Performance in a Distance-Based Cycling Trial. Frontiers in Physiology. doi: 10.3389/fphys.2018.00227

Li et al. (2017). A New Method for Human Mental Fatigue Detection with Several EEG Channels. Journal of Medical and Biological Engineering. DOI: 10.1007/s40846-017-0224-6

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Autor: Heloiana Karoliny Campos Faro
#eeglatam #eegdataanalysis #semioticsresearch #attentionperceptionaction #attentioncontrolconsciousness #executivelegislativejudgmentfunctions #stresslearningbullying #sentienceconsciousness #inhibitorycontrolswitching









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