*2.5. Data Analyses*

#### 2.5.1. Behavioral Data

Behavioral data were compared between conditions (fatigued vs. rested) using paired *t*-tests. All tests were performed with IBM SPSS Statistics software.

#### 2.5.2. Imaging Data

Imaging data analysis was performed using FSL 5.09, FEAT Version 6.0 [18]. Standard pre-processing steps were performed: correction of head movements with the MCFLIRT tool, and removal of non-brain voxels from images with the BET tool. Global intensity normalization of images with a single factor and a Gaussian-weighted least-squares straight line fitting, with sigma = 45.0 s, was performed. Registration and normalization results were visually inspected for each participant. Level 1 analysis was performed using the FILM tool with local autocorrelation correction. The main effect of active blocks was examined. The Z > 3.1 threshold was applied with the use of clusters and the corrected cluster significance threshold *p* < 0.05. Level 2 analysis was performed in the mixed-effects model, with a participant as a random factor; the significance of stimuli was determined by threshold Z > 3.1 with the use of clusters and adjusted significance threshold *p* < 0.05. The whole-brain main effects analyses were intended to reveal level 2 group means for each condition separately (i.e., the difference between active and baseline blocks). The correlations of the activations with reaction times were evaluated separately for each condition. The effect of condition was tested with a T-statistics contrast between conditions. We analyzed contrasts fatigued > rested as well as rested > fatigued.
