Abstract
Objective To investigate whether and how the working memory impairment induced by sleep deprivation (SD) could be recovered by using repetitive transcranial magnetic stimulation (rTMS), as well as to clarify the corresponding brain activity changes. Methods Seventeen healthy adults received one session of 5.0 Hz rTMS over the left dorsolateral prefrontal cortex (DLPFC) following 24 hours of SD. Resting state functional magnetic resonance imaging (fMRI) and working memory test were performed during a rested waking period, after SD and rTMS. The amplitude of low-frequency fluctuations (ALFF) was used to detect the spontaneous neural activity changes after both SD and rTMS. The relationship between ALFF and the performance of working memory was also assessed by using correlation analysis. Results After SD, the participants exhibited lower response accuracies and longer reaction times on the working memory tests of letters and numbers. The decreased response accuracy of numbers was significantly improved after rTMS similarly to the state of the rested waking period after a normal night of sleep. ALFF values decreased from the rested waking period state to the state of SD in the brain regions involving the frontal gyrus, precuneus, angular gyrus, and parietal lobe which showed significantly increased ALFF after rTMS. Furthermore, significantly positive correlations were observed between changes of response accuracy and the changes of ALFF value of the inferior frontal gyrus and supramarginal gyrus. Conclusion These results indicate that high-frequency rTMS applied over left DLPFC may contribute to the recovery of the impaired working memory after SD by modulating the neural activity of related brain regions.
Highlights
Substantial studies have reported that sleep deprivation (SD) impairs various aspects of cognition involving working memory, verbal learning, attention, and processing speed [1,2,3,4,5]
No significant main effects were identified for response accuracy in letter (Fð2,48Þ = 0:311, p = 0:734) and number (Fð2,48Þ = 3:077, p = 0:055) and reaction time in letter (Fð2,48Þ = 0:917, p = 0:406) and number (Fð2,48Þ = 1:729, p = 0:188)
The response accuracies of the letter (p = 0:435) and number tests were increased after repetitive transcranial magnetic stimulation (rTMS) treatment in contrast to SD and showed significant changes in the response accuracy of number (p = 0:026)
Summary
Substantial studies have reported that sleep deprivation (SD) impairs various aspects of cognition involving working memory, verbal learning, attention, and processing speed [1,2,3,4,5]. Previous neuroimaging studies that utilized functional magnetic resonance imaging (fMRI), arterial spin labeling (ASL), and positron emission tomography (PET) have suggested that detriments in specific cognitive functions accompanying SD can be associated with the abnormal changes of regional cerebral blood flow, metabolic rate of glucose, and neural activation, as well as the functional brain networks of cerebral systems [2, 10,11,12,13]. These influences on cerebral responses show hyperactivation or lower activation which were most prominent in cognition-related brain areas
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