217 Attention Regulation in Narcolepsy Type 1 Error-related effect People with narcolepsy type 1 had significantly lower activation than controls in the left pre- and postcentral gyrus when making more errors. The primary motor and primary somatosensory motor cortex are known to be involved in motor response inhibition [304, 305] and activation in these regions seems reasonable as most errors were errors of commission where the button should not have been pressed. Previous studies have shown that people with narcolepsy in general experience difficulties in impulsivity and response inhibition, specifically under time pressure [306, 307]. Our results could therefore reflect the motor preparation-related aspect of these cognitive problems. Study limitations All people with narcolepsy type 1 underwent extensive diagnostic testing, including genetic screening, and discontinued medication prior to study start to ensure homogeneity of the group, but it should be noted that this study only included relatively small participant groups. Future studies should include larger participant groups. In the traditional SART a monotonous task is performed for 4.19 min without interruptions. We needed to design the experiment in a way that conformed to limitations of the method, i.e., MRI-related signal drift. We therefore frequently alternated baseline and task conditions. This substantially limits the possibility of measuring continuous episodes of vigilance. Different neuroimaging modalities, such as electroencephalography (EEG) or magnetoencephalography (MEG), that are not susceptible to signal drift, could possibly be employed in future research. We were unable to perform event-related analyses on error-related processing as a result of sparsity of errors. We suggest, therefore, that the task is extended and that only the higher difficulty level is used to increase the number of errors. Conclusions The modified version of the SART with varying levels of vigilance demand is a feasible MRI vigilance task for use in both people with narcolepsy type 1 and in healthy controls. Being vigilant during the performance of the SART resulted in activation of neural attention, motor (control), arousal, and visual networks. Even though people with narcolepsy type 1 made significantly more mistakes with increasing difficulty compared to relative stable performance in healthy controls, similar vigilance networks were activated during the task. Within 7
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