The Role of Brain Activation and Cerebral Blood Flow in Mental Fatigue.

To assess the changes in brain activation and cerebral blood flow due to mental fatigue in a placebo-controlled study. More specifically we want to assess whether brain activation [measured with Blood Oxygen Level Dependent (BOLD) functional resonance imaging (fMRI)] is decreased during a Flanker task in a mentally fatigued state and whether this coincides with a decline in cognitive performance. In addition we also want to evaluate whether cerebral blood flow [measured with arterial spin labeled (ASL) fMRI] in a resting state is reduced when mentally fatigued.

A modified Stroop task of 90 min, partitioned in 8 blocks of 252 stimuli, will be used as mentally fatiguing task.

In the control task subjects will have to watch a documentary on the same computer screen as that used for the experimental trial for 90 min.

A modified Stroop task of 90 min, partitioned in 8 blocks of 252 stimuli, will be used as mentally fatiguing task. The Stroop task requires inhibition and sustained attention on controlled processes.

In the control task subjects will have to watch a documentary on the same computer screen as that used for the experimental trial. These documentaries are chosen based on their emotionally neutral, yet engaging content.

Blood Oxygen Level Dependent - Signal will be measured during a 10-min Flanker task that will be completed immediately before and after the 90-min task (i.e. documentary in control trial; stroop task in intervention trial)

Blood Oxygen Level Dependent - Signal will be measured during a 10-min Flanker task that will be completed immediately prior and after the 90-min task that is completed in both trials.

Inclusion Criteria: Healthy (No neurological/cardiorespiratory/psychological disorders) No medication Non-smoker Between 18 and 35 years old Exclusion Criteria: Injuries Illness Pacemaker, neurostimulator, medication pump or metal implants Use of medication or any kind of drugs Use of alcohol, caffeine and heavy efforts 24 hours before each trial Not eating the same meal the night before and the morning of each trial

Van Cutsem J, Van Schuerbeek P, Pattyn N, Raeymaekers H, De Mey J, Meeusen R, Roelands B. A drop in cognitive performance, whodunit? Subjective mental fatigue, brain deactivation or increased parasympathetic activity? It's complicated! Cortex. 2022 Oct;155:30-45. doi: 10.1016/j.cortex.2022.06.006. Epub 2022 Jun 30.