Differential Functional Network Remodeling Induced by Low- and High-Frequency rTMS: Evidence From Concurrent fNIRS...

Area of Science:

• Neuroscience
• Rehabilitation Medicine
• Biomedical Engineering

Background:

• Repetitive transcranial magnetic stimulation (rTMS) is recognized for facilitating motor recovery post-stroke.
• The precise neural network mechanisms underlying rTMS efficacy, particularly the differences between low-frequency (LF) and high-frequency (HF) stimulation, remain incompletely understood.
• Understanding these mechanisms is crucial for optimizing rTMS protocols for stroke rehabilitation.

Purpose of the Study:

• To investigate the immediate effects of LF- and HF-rTMS on functional brain network remodeling using functional near-infrared spectroscopy (fNIRS).
• To explore the long-term impact of rTMS-induced neural changes on motor function recovery in stroke patients.
• To establish a correlation between neural modulation and behavioral outcomes following rTMS intervention.

Main Methods:

• A randomized controlled trial involving 108 stroke patients assigned to LF-rTMS, HF-rTMS, or Sham groups over 15 days.
• Real-time monitoring of hemodynamic changes using fNIRS during rTMS interventions.
• Analysis of functional network remodeling using laterality index (LI) and wavelet phase coherence (WPCO); assessment of behavioral outcomes via clinical scales.

Main Results:

• LF-rTMS significantly increased LI and induced immediate WPCO changes between motor regions during initial stimulation.
• HF-rTMS demonstrated delayed but significant WPCO alterations, with sustained intervention modulating both motor and cognitive networks.
• Both LF- and HF-rTMS groups showed significant behavioral improvements after 15 days, correlated with observed WPCO changes.

Conclusions:

• The rTMS-fNIRS approach provides mechanistic evidence for rTMS in promoting functional recovery by modulating neural networks.
• LF-rTMS may mitigate interhemispheric inhibition and improve motor function in the short term.
• HF-rTMS requires sustained stimulation for network remodeling, potentially offering broader rehabilitative benefits for motor and cognitive functions.