Introduction: Resting-state functional connectivity (fcMRI) represents anovel fMRI approach that allows detection of temporal correlations in spontaneousBOLD signal oscillations while subjects rest quietly in the scanner.Under resting conditions the brain is engaged in spontaneous activity thatcauses a low frequencies (<0.1 Hz) BOLD signal fluctuations. Functional connectivity(FC) can be defined as the synchrony of neural activity amongspatially distant regions.Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulationtechnique that is known to modulate cortical activity and FC amongbrain regions, as measured by functional magnetic resonance imaging.This study is aimed at measuring the variation of functional connectivitybetween cortical brain regions after tDCS along time.Materials and Methods: For this purpose we enrolled 20 healthy righthandedsubjects. All subjects underwent 4 sessions RS-fMRI (10’ each, TR2’’, 300 volumes, 1.5 T scanner): 2 immediately before and 2 after 20’ tDCSover leftM1. 10 of them received real (anodal) tDCS, 10 received sham stimulation.We analyzed FC between left and right M1 with two differentstatistical analyses: Seed-based correlation analysis (SCA) and the temporalconcatenation group ICA (TC-GICA).Results: Seed-based correlation analysis showed a significant decrease ofFC during the first fMRI acquisition immediately after anodal tDCS stimulation(p = 0.005) that reaches back to baseline during the last fMRI session.This behavior was not found in subjects who underwent sham stimulation(p = 0.12).The temporal concatenation group ICA showed that immediately after anodalstimulation the average value of voxels decreases significantly (p < 0.05)whereas there is no significant decrease in the case of sham tDCS stimulation.Conclusions: Our results show that anodal tDCS is able to induce connectivitychanges within motor network, that is, reversible in a period lastingbetween 10’ and 20’ after stimulation.
|Number of pages||2|
|Publication status||Published - 2016|