Long-Term Functional Connectivity Changes Across The Dorsal Attention Network After Transcranial Electrical Stimulation

Abstract

Introduction: High-frequency tRNS (hf-tRNS) has been shown to modulate ongoing cortical oscillations and facilitate behavior in a number of cognitive tasks, including sustained attention (Tyler et al., in press). These studies mainly analyze the neuromodulatory effects by measuring changes in performance. However, the impact of hf-tRNS on large-scale cortical networks is still unknown. In this study we investigated the impact of multi-session hf-tRNS coupled with behavioral training on resting-state fMRI before and after training. Methods: Thirty-three subjects participated in a 6-days experiment. Subjects received 25min hf-tRNS or sham while training on an interleaved visual and temporal attention task for 4 consecutive days (day 2-5). Subjects were assigned to one of three conditions in a between-subject design: 1) hf-tRNS over parietal cortex, 2) over hMT+, and 3) sham stimulation. Before and after the training phase (day 1 and 6), we measured rs-fMRI of selected nodes of the Dorsal Attention Network (DAN). To detect changes in functional connectivity, correlation matrices containing all DAN nodes were calculated and compared before and after hf-tRNS and between stimulation conditions. We expected concurrent hf-tRNS to affect large-scale functionally selective attention network. Results: Resting state functional connectivity patterns significantly increased within the main nodes of the DAN (in particular hMT+, IPS and FEF) after parietal stimulation. No significant changes were found for the hMT+, nor sham group. Crucially, behavioral performance significantly improved for subjects in the parietal group only. Conclusions: tRNS has a sustained and selective effect upon functional networks involved in attentional training. Changes in resting state functional connectivity within the DAN demonstrate how noninvasive cortical modulation can boost behavior after very short training. This work highlights the importance of a network perspective to understand the impact of brain stimulation on the brain.

Meeting abstract presented at VSS 2018