Capturing Neuroplastic Changes after iTBS in Patients with Post-Stroke Aphasia: A Pilot fMRI Study.

Shuo Xu,Panmo Deng,Yongli Zhang,Mengye Chen,Qing Yang,Ren Zhuang,Zengchun Sun,Jie Jia,Chong Li,Zhijie Yan

doi:10.3390/brainsci11111451

Abstract

Intermittent theta-burst stimulation (iTBS) is a high-efficiency transcranial magnetic stimulation (TMS) paradigm that has been applied to post-stroke aphasia (PSA). However, its efficacy mechanisms have not been clarified. This study aimed to explore the immediate effects of iTBS of the primary motor cortex (M1) of the affected hemisphere, on the functional activities and connectivity of the brains of PSA patients. A total of 16 patients with aphasia after stroke received iTBS with 800 pulses for 300 s. All patients underwent motor, language, and cognitive assessments and resting-state functional MRI scans immediately before and after the iTBS intervention. Regional, seed-based connectivity, and graph-based measures were used to test the immediate functional effects of the iTBS intervention, including the fractional amplitude of low-frequency fluctuation (fALFF), degree centrality (DC), and functional connectivity (FC) of the left M1 area throughout the whole brain. The results showed that after one session of iTBS intervention, the fALFF, DC, and FC values changed significantly in the patients’ brains. Specifically, the DC values were significantly higher in the right middle frontal gyrus and parts of the left parietal lobe (p < 0.05), while fALFF values were significantly lower in the right medial frontal lobe and parts of the left intracalcarine cortex (p < 0.05), and the strength of the functional connectivity between the left M1 area and the left superior frontal gyrus was reduced (p < 0.05). Our findings provided preliminary evidences that the iTBS on the ipsilesional M1 could induce neural activity and functional connectivity changes in the motor, language, and other brain regions in patients with PSA, which may promote neuroplasticity and functional recovery.

Highlights

Patients with post-stroke aphasia (PSA) often have impaired upper extremity (UE) motor and cognitive function [1,2,3]
After a combination of Intermittent theta-burst stimulation (iTBS) and fMRI, our results reveal that iTBS acting on the M1 area of the affected hemisphere can cause altered cortical excitability and functional connectivity of different regions, which may further lead to orientative neural plasticity in language- and cognition-related functional areas of the brain
We found that after 200 s iTBS intervention, fractional amplitude of low-frequency fluctuation (fALFF), degree centrality (DC), and functional connectivity (FC) all changed to different degrees, which is an indication of the immediate effects of iTBS and is promising for neural plasticity after PSA

Summary

Introduction

Patients with post-stroke aphasia (PSA) often have impaired upper extremity (UE) motor and cognitive function [1,2,3]. The structural and functional connectivity have been identified between the brain’s language and motor areas in healthy volunteers and the patients with various neurological disorders [10,11,12,13], it is still not clear if and how the NIBS targeting the M1 would affect the language function via these connections We conducted this preliminary functional MRI study to investigate the immediate brain functional effects of the left M1 stimulation with intermittent theta-burst stimulation (iTBS), which is a popular TMS method, in treating PSA using resting-state functional magnetic resonance (fMRI) images

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