Brain plasticity following MI-BCI training combined with tDCS in a randomized trial in chronic subcortical stroke subjects: a preliminary study

Xin Hong,Cuntai Guan,Wei Peng Teo,Zhong Kang Lu,Kai-Hsiang Chuang,Fatima Ali Nasrallah,Irvin Teh,Effie Chew,Kok Soon Phua,Kai Keng Ang

doi:10.1038/s41598-017-08928-5

Abstract

Brain-computer interface-assisted motor imagery (MI-BCI) or transcranial direct current stimulation (tDCS) has been used in stroke rehabilitation, though their combinatory effect is unknown. We investigated brain plasticity following a combined MI-BCI and tDCS intervention in chronic subcortical stroke patients with unilateral upper limb disability. Nineteen patients were randomized into tDCS and sham-tDCS groups. Diffusion and perfusion MRI, and transcranial magnetic stimulation were used to study structural connectivity, cerebral blood flow (CBF), and corticospinal excitability, respectively, before and 4 weeks after the 2-week intervention. After quality control, thirteen subjects were included in the CBF analysis. Eleven healthy controls underwent 2 sessions of MRI for reproducibility study. Whereas motor performance showed comparable improvement, long-lasting neuroplasticity can only be detected in the tDCS group, where white matter integrity in the ipsilesional corticospinal tract and bilateral corpus callosum was increased but sensorimotor CBF was decreased, particularly in the ipsilesional side. CBF change in the bilateral parietal cortices also correlated with motor function improvement, consistent with the increased white matter integrity in the corpus callosum connecting these regions, suggesting an involvement of interhemispheric interaction. The preliminary results indicate that tDCS may facilitate neuroplasticity and suggest the potential for refining rehabilitation strategies for stroke patients.

Highlights

Facilitating integration with motor learning, MI-BCI has been demonstrated to be a promising tool for improving functional recovery in stroke patients[1,2,3,4,5,6,7]
We investigated whether combining transcranial direct current stimulation (tDCS) and MI-BCI may further improve neuroplasticity and functional recovery in stroke survivors with motor impairments
We hypothesized that the combination of tDCS with MI-BCI training will induce greater and longer-lasting neuroplasticity in the white matter tracts, gray matter function, and excitability of the corticospinal pathway compared to MI-BCI alone

Summary

Introduction

Facilitating integration with motor learning, MI-BCI has been demonstrated to be a promising tool for improving functional recovery in stroke patients[1,2,3,4,5,6,7]. FA is usually thought to reflect the overall integrity of the axonal fibers These DTI metrics could provide useful information in stroke patients to determine the extent of the WM lesion[20], the relationship with functional recovery[21, 22], and process of intervention/recovery[23]. We applied DTI, ASL and TMS to understand the changes in gray and white matter and excitability of the corticospinal pathway before, immediately after 2 weeks of anodal tDCS and MI-BCI and 4 weeks post-intervention in moderate-to-severe stroke patients with upper limb disability. Our results show that adding tDCS can induce long-lasting changes in cortical excitability and CBF, as well as enhance the integrity in white matter connecting the bilateral sensorimotor cortices

Methods

Results

Discussion

Conclusion