Effects of transcranial magnetic stimulation on dynamic functional networks in stroke patients as assessed by functional near-infrared spectroscopy: a randomized controlled clinical trial

Studies have shown that there is heterogeneity in the efficacy bewteen the low-frequency (LF) and high-frequency (HF) repetitive transcranial magnetic stimulation (rTMS), but the neural mechanisms underlying the differences in efficacy remain unclear. This study aimed to investigate the specific effects of LF- and HF-rTMS on cortial functional network and the process of neural regulation. A total of sixty-eight patients with hemiplegic motor impairment after stroke were randomly allocated to one of three groups: the LF-rTMS, HF-rTMS, and sham groups. Tissue concentrations of oxyhaemoglobin and deoxyhaemoglobin oscillations in cerebral cortex regions were measured by functional near-infrared spectroscopy (fNIRS) in the resting and rTMS states. Four specific time-windows were divided from the trial duration to observe dynamic changes in cortical haemodynamic responses. Compared with sham, LF-rTMS significantly induced the activation of the contralesional superior frontal cortex and premotor cortex, and continuously regulated ipsilesional hemisphere functional networks in stroke patients. However, HF-rTMS did not induce a significant neurovascular coupling response. Our study provided evidence that LF- and HF-rTMS interventions induced different neurovascular coupling responses and demonstrated the cortical functional network change process of rTMS in specific time-windows. These findings may help to understand the differences in the efficacy of rTMS modalities.