229 Active Sleep Resistance in Narcolepsy Type 1 individual EEG electrode signals through sliding Hanning window regression (six second windows). This final step eliminated the non-brain signals from the EEG signals. Cleaned EEG recordings were used for sleep scoring according to AASM criteria using 30 s epochs; note, though, that no EMG measurements were obtained. Functional MRI acquisition and processing Whole-brain T2*-weighted and T1-weighted scans were acquired with the same parameters as in Gool et al. (2020) [266]. T2*-weighted MRI data were acquired using a gradient-echo planar imaging (EPI) sequence (38 slices with a 0.25 mm gap; repetition time [TR] = 2250 ms; echo time [TE] = 29.94 ms; field of view [FOV] 200 mm × 200 mm × 104.25 mm; matrix size 80 × 80; flip angle = 80°; 2.5 mm × 2.5 mm × 2.5 mm voxel size). T1-weighted MR images were acquired (220 slices; TR 8.2 ms; TE 3.8 ms; inversion time 670.4 ms; FOV 240 mm × 240 mm × 220 mm; matrix size 240 × 240; flip angle 8°; 1 mm × 1 mm × 1 mm voxel size). The fMRI images were pre-processed and analysed using FMRIB’s Software Library (FSL FEAT, version 6.0.4). Scans were motion corrected using MCFLIRT, brain extracted, normalized, filtered using a 100 s high-pass filter, smoothed with a 5 mm full-width at half maximum (FWHM) Gaussian kernel and coregistered to the corresponding skull-stripped T1 image. FILM prewhitening was implemented as a non-parametric estimation of each voxel’s time series autocorrelation, a temporal derivative was added to account for hemodynamic response function deviations and the derived motion parameters were included as nuisance regressors in the general linear model. First-level within-subject effects were assessed using the mean BOLD response of the sleep resistance blocks in comparison to mean activation of the wakeful rest blocks. The transition periods between task conditions, possible sleep epochs, and possible delays in following task instructions as checked through EOG monitoring, were excluded in first-level analyses. The second-level main task fMRI effects were determined per group using one-sample t-tests. For group comparisons, two-sample t-tests were used. The main task effect analyses were performed in the entire sample and controlled for type I errors using family-wise error (FWE) correction. Clustercorrection was implemented for the group comparison. Two post hoc analyses were performed for people with narcolepsy to test whether between group differences were related to patient-specific markers. ESS scores and disease duration – measured as duration since EDS onset – were, respectively, added as covariates of interest in second-level analyses just including people with 8
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