Increased resting state connectivity between ipsilesional motor cortex and contralesional premotor cortex after transcranial direct current stimulation with physical therapy.

Joyce L Chen,Gottfried Schlaug

doi:10.1038/srep23271

Abstract

Non-invasive stimulation of the brain using transcranial direct current stimulation (tDCS) during motor rehabilitation can improve the recovery of movements in individuals with stroke. However, the neural substrates that underlie the clinical improvements are not well understood. In this proof-of-principle open-label pilot study, five individuals with stroke received 10 sessions of tDCS while undergoing usual care physical/occupational therapy for the arm and hand. Motor impairment as indexed by the Upper Extremity Fugl Meyer assessment was significantly reduced after the intervention. Resting state fMRI connectivity increased between ipsilesional motor cortex and contralesional premotor cortex after the intervention. These findings provide preliminary evidence that the neural underpinnings of tDCS coupled with rehabilitation exercises, may be mediated by interactions between motor and premotor cortex. The latter, of which has been shown to play an important role in the recovery of movements post-stroke. Our data suggest premotor cortex could be tested as a target region for non-invasive brain-stimulation to enhance connectivity between regions that might be beneficial for stroke motor recovery.

Highlights

An advantage of rsfMRI is that participants are scanned while “resting”, which avoids the problem of controlling for effort and performance when stroke patients with varying motor deficits are studied using the task-based fMRI approach[19,20]
There were no significant changes in connectivity between the contralesional motor cortex seed region with any voxels, for either the primary or secondary analyses. In this proof-of-principle pilot study, individuals with chronic stroke underwent resting state fMRI before and after an intervention comprising 10 sessions of transcranial direct current stimulation (tDCS) combined with physical and occupational therapy (PT/OT)
Our findings demonstrate that at post-intervention, there was: 1) a significant reduction in motor impairment for all individuals, and 2) an increased resting state connectivity between ipsilesional motor cortex with contralesional premotor cortex and bilateral precuneus

Summary

Introduction

An advantage of rsfMRI is that participants are scanned while “resting”, which avoids the problem of controlling for effort and performance when stroke patients with varying motor deficits are studied using the task-based fMRI approach[19,20]. No studies have examined resting state connectivity changes associated with a combined tDCS + PT/OT intervention for stroke patients. In stroke patients, resting state interhemispheric connectivity between motor regions positively correlates with motor outcome; individuals with higher connectivity are less impaired and have better function[21,22,23]. We explore whether resting state connectivity between interhemispheric motor regions would increase post-intervention

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