Asymmetric effects of anodal transcranial direct current stimulation on intrinsic connectivity in the left and right dorsolateral prefrontal cortex
Year: 2023
Type: dissertation
Study design: Clinical Trial
Abstract: Transcranial direct current stimulation (tDCS) applied to the dorsolateral prefrontal cortex (DLPFC) has been shown to have asymmetric behavioral effects, but the underlaying neurophysiological mechanisms causing these asymmetric behavioral differences are poorly understood. Functional magnetic resonance imaging (fMRI) can be used in conjunction with a behavioral measurement to better understand these mechanisms. To measure the hemispheric laterality of neurophysiological and behavioral effects of anodal tDCS applied to the left and right DLPFC using fMRI and Stroop test interference, 11 male and 28 female healthy participants were randomized into three treatment groups of 1.5mA anodal tDCS applied to sham or the left or right the DLPFC, with the cathode placed on the contralateral supraorbital region. Before and after tDCS application participants took the Stroop test and underwent resting-state fMRI. Seed-to-voxel functional connectivity and voxel-to-voxel whole brain intrinsic connectivity (IC) analyses were performed on the fMRI data. All fMRI analysis was done by using two sets of 2×2 factorial analyses between groups (real vs. sham) and time (pre- vs. post-tDCS) for each left and right tDCS, separately, while Stroop interference was measured using a repeated measures general linear model. tDCS to the left DLPFC in the voxel-to-voxel analysis resulted in three significant clusters of changed IC, with one of the clusters being an increase of IC in the left prefrontal region. tDCS to the right DLPFC in the voxel-to-voxel analysis resulted in only one significant cluster of decreased IC in the right prefrontal region. For Stroop interference, only tDCS to the right DLPFC improved Stroop interference performance with left and sham causing no significant changes. No significant changes were found for seed-to-voxel analysis. This study shows that tDCS applied to the left and right DLPFC causes asymmetric changes to IC, as well as providing further support that the DLPFC is asymmetric in interference control, with only tDCS to the right DLPFC having a significant effect on interference.
Source: Mspace (University of Manitoba)
Author: McAllister, Zachary
Institution: University of Manitoba
Language: English
Subfield: Neurology
Field: Neuroscience
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W7017283244