Task-related brain functional network reconfigurations relate to motor recovery in chronic subcortical stroke

Hsiao-Ju Cheng,Kai Keng Ang,Wei Peng Teo,Xing Qian,Juan Helen Zhou,Zhong Kang Lu,Fang Ji,Kwun Kei Ng,Haoyong Yu,Effie Chew,Fatima Ali Nasrallah,Kai-Hsiang Chuang,Cuntai Guan,Xin Hong

doi:10.1038/s41598-021-87789-5

Abstract

Stroke leads to both regional brain functional disruptions and network reorganization. However, how brain functional networks reconfigure as task demand increases in stroke patients and whether such reorganization at baseline would facilitate post-stroke motor recovery are largely unknown. To address this gap, brain functional connectivity (FC) were examined at rest and motor tasks in eighteen chronic subcortical stroke patients and eleven age-matched healthy controls. Stroke patients underwent a 2-week intervention using a motor imagery-assisted brain computer interface-based (MI-BCI) training with or without transcranial direct current stimulation (tDCS). Motor recovery was determined by calculating the changes of the upper extremity component of the Fugl–Meyer Assessment (FMA) score between pre- and post-intervention divided by the pre-intervention FMA score. The results suggested that as task demand increased (i.e., from resting to passive unaffected hand gripping and to active affected hand gripping), patients showed greater FC disruptions in cognitive networks including the default and dorsal attention networks. Compared to controls, patients had lower task-related spatial similarity in the somatomotor–subcortical, default–somatomotor, salience/ventral attention–subcortical and subcortical–subcortical connections, suggesting greater inefficiency in motor execution. Importantly, higher baseline network-specific FC strength (e.g., dorsal attention and somatomotor) and more efficient brain network reconfigurations (e.g., somatomotor and subcortical) from rest to active affected hand gripping at baseline were related to better future motor recovery. Our findings underscore the importance of studying functional network reorganization during task-free and task conditions for motor recovery prediction in stroke.

Highlights

Stroke leads to both regional brain functional disruptions and network reorganization
In the task-free condition, compared to age-matched healthy controls, we observed that stroke patients had lower intra-network functional connectivity (FC) (NBS corrected p = 0.037, Cohen’s d = 0.016) in bilateral control, salience/ventral attention, and subcortical networks as well as lower inter-network FC between ipsilesional control and bilateral subcortical networks (Fig. 1A and Supplementary Figure 2)
In the task-general condition, we observed that stroke patients had more extensive network disruptions in the task condition compared to the rest condition, namely lower intra-network FC in bilateral default, control, salience/ventral attention, somatomotor and subcortical networks

Summary

Introduction

Stroke leads to both regional brain functional disruptions and network reorganization. How brain functional networks reconfigure as task demand increases in stroke patients and whether such reorganization at baseline would facilitate post-stroke motor recovery are largely unknown. To address this gap, brain functional connectivity (FC) were examined at rest and motor tasks in eighteen chronic subcortical stroke patients and eleven age-matched healthy controls. Increased FC in ipsilesional dorsal attention and default networks in stroke patients compared to healthy controls was n oted[8] These findings pointed to network-specific changes at task-free condition after stroke. Little is known about how brain functional networks reconfigure from rest to task in stroke patients and how these functional network disruptions or reorganization at baseline influence post-stroke motor recovery

Methods

Results

Discussion

Conclusion