Abstract
BackgroundThe mu event-related desynchronization (ERD) is supposed to reflect motor preparation and appear during motor imagery. The aim of this study is to examine the modulation of ERD with transcranial direct current stimulation (tDCS).MethodsSix healthy subjects were asked to imagine their right hand grasping something after receiving a visual cue. Electroencephalograms (EEGs) were recorded near the left M1. ERD of the mu rhythm (mu ERD) by right hand motor imagery was measured. tDCS (10 min, 1 mA) was used to modulate the cortical excitability of M1. Anodal, cathodal, and sham tDCS were tested in each subject with a randomized sequence on different days. Each condition was separated from the preceding one by more than 1 week in the same subject. Before and after tDCS, mu ERD was assessed. The motor thresholds (MT) of the left M1 were also measured with transcranial magnetic stimulation.ResultsMu ERD significantly increased after anodal stimulation, whereas it significantly decreased after cathodal stimulation. There was a significant correlation between mu ERD and MT.ConclusionsOpposing effects on mu ERD based on the orientation of the stimulation suggest that mu ERD is affected by cortical excitability.
Highlights
The mu event-related desynchronization (ERD) is supposed to reflect motor preparation and appear during motor imagery
We studied whether transcranial direct current stimulation (tDCS) application could modulate the cortical signal, such as mu ERD during right hand grasping images
Further analysis was performed with these electrode pairs to assess the effect of tDCS on mu ERD by motor imagery
Summary
The mu event-related desynchronization (ERD) is supposed to reflect motor preparation and appear during motor imagery. The mu rhythm is attenuated by tactile stimulation, movement execution, and motor imagery, which are referred to as event-related desynchronization (ERD) [1,4,5]. Such ERD of mu rhythm, named mu ERD in this paper, are interpreted as the desynchronized activities of Amplitude changes due to externally or internally paced events are interpreted as the desynchronization or synchronization of neural activities of the cortex neurons. A recent study showed that mu ERD in preparation for contralateral extremity movement has some relationships with cortical activity seen on fMRI [6]. It is thought that there might be some relationship between cortical excitability and mu ERD
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