Abstract
Transcranial alternating current stimulation (tACS) is an emerging non-invasive neuromodulation technique, which could be potentially applied to enhance stroke rehabilitation. In this study, we aimed to characterize the frequency-specific effects of tACS in chronic stroke. Therefore, concurrent tACS and functional magnetic resonance imaging (fMRI) were conducted in 13 chronic stroke individuals. Resting-state and task-based fMRI were collected for each subject under different frequencies (10 Hz, 20 Hz, Sham). Task-based fMRI showed that increased activation was found in the ipsilesional precentral area during paretic hand movements after 10 Hz tACS, while increased activation was found in the contralesional precentral area during non-paretic hand movements after both 10 and 20 Hz tACS. Resting-state seed-based functional connectivity (FC) analysis showed that 10 Hz tACS mainly modulated FC within motor-related regions, while 20 Hz tACS also modulated regions beyond the motor-related areas. Graph theory analysis further demonstrated the functional interaction modulated by tACS in the whole-brain level. Taken together, our results showed that tACS might exhibit frequency-specific modulation in chronic stroke. 20 Hz tACS facilitates the functional interaction between the sensorimotor regions and brain regions involved in executive control, while 10 Hz and sham tACS has limited effect on motor-related brain activity. Our results reveal the neural response process under external current stimulation, providing new insight into the neuromodulation mechanism of tACS in a lesioned brain.
Highlights
S TROKE is a leading cause of disability, and the demand for stroke rehabilitation is increasing [1]
Following 10 Hz Transcranial alternating current stimulation (tACS), paired t-tests revealed that significantly increased activation was found in the ipsilesional precentral area with an MNI coordinate of (57,5,44) and contralesional insula (38,13,19) during paretic hand movements (Fig.2(B)), and significantly increased activation was found in the contralesional precentral area (-59,2,22) during non-paretic hand movements (Fig.2(C))
The current study thoroughly explored the frequencyspecific tACS effects in chronic stroke subjects
Summary
S TROKE is a leading cause of disability, and the demand for stroke rehabilitation is increasing [1]. The existence of neuroplasticity makes it possible for various rehabilitation methods [2][3]. More and more clinical studies have been focused on novel interventions aiming at enhancing the neuroplasticity in stroke subjects, including non-invasive brain stimulation [4][5]. Transcranial alternating current stimulation (tACS) opens a new era of non-invasive electrical stimulation by directly interfering with cortical rhythms [6]. The neurophysiological mechanisms of tACS are still not thoroughly understood. It is believed that the frequency-specific entrainment effects play an important role in modulating endogenous
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Schedule a callMore From: IEEE transactions on neural systems and rehabilitation engineering : a publication of the IEEE Engineering in Medicine and Biology Society
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