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Dissociation between mental fatigue and motivational state during prolonged mental activity.

Gergelyfi M, Jacob B, Olivier E, Zénon A - Front Behav Neurosci (2015)

Bottom Line: An influential hypothesis states that MF does not arise from a disruption of overused neural processes but, rather, is caused by a progressive decrease in motivation-related task engagement.Finally, alterations of the motivational state through monetary incentives failed to compensate the effects of MF.These findings indicate that MF in healthy subjects is not caused by an alteration of task engagement but is likely to be the consequence of a decrease in the efficiency, or availability, of cognitive resources.

View Article: PubMed Central - PubMed

Affiliation: Institute of Neuroscience, Université Catholique de Louvain Brussels, Belgium.

ABSTRACT
Mental fatigue (MF) is commonly observed following prolonged cognitive activity and can have major repercussions on the daily life of patients as well as healthy individuals. Despite its important impact, the cognitive processes involved in MF remain largely unknown. An influential hypothesis states that MF does not arise from a disruption of overused neural processes but, rather, is caused by a progressive decrease in motivation-related task engagement. Here, to test this hypothesis, we measured various neural, autonomic, psychometric and behavioral signatures of MF and motivation (EEG, ECG, pupil size, eye blinks, Skin conductance responses (SCRs), questionnaires and performance in a working memory (WM) task) in healthy volunteers, while MF was induced by Sudoku tasks performed for 120 min. Moreover extrinsic motivation was manipulated by using different levels of monetary reward. We found that, during the course of the experiment, the participants' subjective feeling of fatigue increased and their performance worsened while their blink rate and heart rate variability (HRV) increased. Conversely, reward-induced EEG, pupillometric and skin conductance signal changes, regarded as indicators of task engagement, remained constant during the experiment, and failed to correlate with the indices of MF. In addition, MF did not affect a simple reaction time task, despite the strong influence of extrinsic motivation on this task. Finally, alterations of the motivational state through monetary incentives failed to compensate the effects of MF. These findings indicate that MF in healthy subjects is not caused by an alteration of task engagement but is likely to be the consequence of a decrease in the efficiency, or availability, of cognitive resources.

No MeSH data available.


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Reward-block interactions on (A) EEG power during the WM task (averaged over the cluster), (B) pupil response during the WM task, (C) SCR during the WM task, (D) RT in the SiRT task and (E) accuracy in the WM task.
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Figure 6: Reward-block interactions on (A) EEG power during the WM task (averaged over the cluster), (B) pupil response during the WM task, (C) SCR during the WM task, (D) RT in the SiRT task and (E) accuracy in the WM task.

Mentions: Finally, in order to evaluate whether the extrinsic motivational manipulations interacted with the fatigue effect, we looked at the interactions between REWARD and BLOCK. The two-way repeated measures ANOVAs on physiological markers of motivation failed to show any significant interaction between REWARD and BLOCK (EEG: F(8,120) = 0.52, p > 0.5, BF = 5.49 × 107, see Figure 6A; pupil response: F(8,120) = 0.68, p > 0.5, BF = 1.7 × 107, see Figure 6B; SCR: F(8,72) = 0.78, p > 0.5, BF = 1119900, see Figure 6C) indicating that the motivational value of the reward did not change throughout the experiment. This lack of interaction was also found on performance in the SiRT (F(8,136) = 0.74, p = 0.65, BF = 1.81 × 108, see Figure 6D).


Dissociation between mental fatigue and motivational state during prolonged mental activity.

Gergelyfi M, Jacob B, Olivier E, Zénon A - Front Behav Neurosci (2015)

Reward-block interactions on (A) EEG power during the WM task (averaged over the cluster), (B) pupil response during the WM task, (C) SCR during the WM task, (D) RT in the SiRT task and (E) accuracy in the WM task.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4499755&req=5

Figure 6: Reward-block interactions on (A) EEG power during the WM task (averaged over the cluster), (B) pupil response during the WM task, (C) SCR during the WM task, (D) RT in the SiRT task and (E) accuracy in the WM task.
Mentions: Finally, in order to evaluate whether the extrinsic motivational manipulations interacted with the fatigue effect, we looked at the interactions between REWARD and BLOCK. The two-way repeated measures ANOVAs on physiological markers of motivation failed to show any significant interaction between REWARD and BLOCK (EEG: F(8,120) = 0.52, p > 0.5, BF = 5.49 × 107, see Figure 6A; pupil response: F(8,120) = 0.68, p > 0.5, BF = 1.7 × 107, see Figure 6B; SCR: F(8,72) = 0.78, p > 0.5, BF = 1119900, see Figure 6C) indicating that the motivational value of the reward did not change throughout the experiment. This lack of interaction was also found on performance in the SiRT (F(8,136) = 0.74, p = 0.65, BF = 1.81 × 108, see Figure 6D).

Bottom Line: An influential hypothesis states that MF does not arise from a disruption of overused neural processes but, rather, is caused by a progressive decrease in motivation-related task engagement.Finally, alterations of the motivational state through monetary incentives failed to compensate the effects of MF.These findings indicate that MF in healthy subjects is not caused by an alteration of task engagement but is likely to be the consequence of a decrease in the efficiency, or availability, of cognitive resources.

View Article: PubMed Central - PubMed

Affiliation: Institute of Neuroscience, Université Catholique de Louvain Brussels, Belgium.

ABSTRACT
Mental fatigue (MF) is commonly observed following prolonged cognitive activity and can have major repercussions on the daily life of patients as well as healthy individuals. Despite its important impact, the cognitive processes involved in MF remain largely unknown. An influential hypothesis states that MF does not arise from a disruption of overused neural processes but, rather, is caused by a progressive decrease in motivation-related task engagement. Here, to test this hypothesis, we measured various neural, autonomic, psychometric and behavioral signatures of MF and motivation (EEG, ECG, pupil size, eye blinks, Skin conductance responses (SCRs), questionnaires and performance in a working memory (WM) task) in healthy volunteers, while MF was induced by Sudoku tasks performed for 120 min. Moreover extrinsic motivation was manipulated by using different levels of monetary reward. We found that, during the course of the experiment, the participants' subjective feeling of fatigue increased and their performance worsened while their blink rate and heart rate variability (HRV) increased. Conversely, reward-induced EEG, pupillometric and skin conductance signal changes, regarded as indicators of task engagement, remained constant during the experiment, and failed to correlate with the indices of MF. In addition, MF did not affect a simple reaction time task, despite the strong influence of extrinsic motivation on this task. Finally, alterations of the motivational state through monetary incentives failed to compensate the effects of MF. These findings indicate that MF in healthy subjects is not caused by an alteration of task engagement but is likely to be the consequence of a decrease in the efficiency, or availability, of cognitive resources.

No MeSH data available.


Related in: MedlinePlus