P117 Effects of transcranial direct current stimulation on the functional coupling of the sensorimotor cortical network.

Introduction Transcranial direct current stimulation (tDCS) is well establishedamong the non-invasive brain stimulation techniques as a method to modulate brain excitability. Polarity-dependent modulations of membrane potentials are detected after the application of anodal and cathodal stimulation, leading to changes in the electrical activity of the neurons. Objective The main aim of the present study was to test the hypothesis that tDCS can affect in a polarityspecific manner the functional coupling of the sensorimotor areas during the eyes-open resting condition as revealed by total EEG coherence (i.e., coherence across the average of all combinations of the electrode pairs placed around the stimulation electrode). Material & methods The changes in the total EEG coherence were evaluated pre-, during, and post-anodal and cathodal tDCS. Results While no differences were observed in the connectivity characteristics of the two pre-stimulation periods, a connectivity increase was observed in the alpha 2 band in the post-anodal tDCS with respect to pre-anodal and post-cathodal tDCS. Conclusions The present study suggests that a specific approach based on the analyses of the functional coupling of EEG rhythms might enhance understanding of tDCS-induced effects on cortical connectivity. Moreover, this result suggests that anodal tDCS could possibly modify cortical connectivity more effectively with respect to cathodal tDCS. [ABSTRACT FROM AUTHOR]