Functional Reorganization After Four-Week Brain-Computer Interface-Controlled Supernumerary Robotic Finger Training: A Pilot Study of Longitudinal Resting-State fMRI.

Yuan Liu,Dong Ming,Zhuang Wang,Shuaifei Huang,Fengrui Ji

doi:10.3389/fnins.2021.766648

Abstract

Humans have long been fascinated by the opportunities afforded through motor augmentation provided by the supernumerary robotic fingers (SRFs) and limbs (SRLs). However, the neuroplasticity mechanism induced by the motor augmentation equipment still needs further investigation. This study focused on the resting-state brain functional reorganization during longitudinal brain–computer interface (BCI)-controlled SRF training in using the fractional amplitude of low-frequency fluctuation (fALFF), regional homogeneity (ReHo), and degree centrality (DC) metrics. Ten right-handed subjects were enrolled for 4 weeks of BCI-controlled SRF training. The behavioral data and the neurological changes were recorded at baseline, training for 2 weeks, training for 4 weeks immediately after, and 2 weeks after the end of training. One-way repeated-measure ANOVA was used to investigate long-term motor improvement [F(2.805,25.24) = 43.94, p < 0.0001] and neurological changes. The fALFF values were significantly modulated in Cerebelum_6_R and correlated with motor function improvement (r = 0.6887, p < 0.0402) from t0 to t2. Besides, Cerebelum_9_R and Vermis_3 were also significantly modulated and showed different trends in longitudinal SRF training in using ReHo metric. At the same time, ReHo values that changed from t0 to t1 in Vermis_3 was significantly correlated with motor function improvement (r = 0.7038, p < 0.0344). We conclude that the compensation and suppression mechanism of the cerebellum existed during BCI-controlled SRF training, and this current result provided evidence to the neuroplasticity mechanism brought by the BCI-controlled motor-augmentation devices.

Highlights

The hands and fingers are the important mediums for humans to interact with the outside world and have a well-established functional representation in the brain (Jones and Lederman, 2006; Dall’Orso et al, 2018; Arcaro et al, 2019)
Despite motor augmentation caused by these devices can be clearly observed in behavioral experiments, little notice is given to the brain neuroplasticity mechanism
degree centrality (DC) mapped the degree of intrinsic functional connectivity (FC) across the brain in order to reflect a stable property of cortical network architecture at the voxel level (Buckner et al, 2009). These three voxel-wise metrics define brain functional characteristics from different perspectives and present the progressive relationship (Lv et al, 2019). This current study aims to fill this gap by investigating the functional reorganization of 4 weeks of brain–computer interface (BCI)-controlled supernumerary robotic fingers (SRF) training based on the new supernumerary robotic finger imagery paradigm

Summary

Introduction

The hands and fingers are the important mediums for humans to interact with the outside world and have a well-established functional representation in the brain (Jones and Lederman, 2006; Dall’Orso et al, 2018; Arcaro et al, 2019). Healthy humans wearing the SRF will rapidly reshape the pattern of corticospinal outputs toward the forearm and hand muscles governing imagined grasping actions of different objects after a few minutes of training (Rossi et al, 2021) and suggesting that human beings are open to very quick welcoming emerging augmentative bioartificial corticospinal grasping strategies. These studies did not pay attention to the long duration training effect on the resting state neuroplasticity of the brain, and these results are affected by the control method of the SRF

Methods

Results

Discussion

Conclusion