Effects of continuous theta burst stimulation on contralateral primary motor cortex: a concurrent TMS-EEG study

Area of Science:

• Neuroscience
• Rehabilitation Medicine
• Brain Stimulation

Background:

• Continuous theta burst stimulation (cTBS) is a noninvasive brain stimulation technique used in motor dysfunction rehabilitation.
• Research on cTBS effects on the contralesional hemisphere is limited.
• Understanding these effects is crucial for optimizing neuromodulation strategies.

Purpose of the Study:

• To investigate the neuroregulatory mechanisms of cTBS in the contralateral cortex.
• To analyze the impact of cTBS on cortical oscillations and network connectivity.
• To provide a theoretical basis for cTBS in stroke rehabilitation.

Main Methods:

• A randomized, sham-controlled, single-blind study involving 18 healthy subjects.
• Application of cTBS or sham stimulation to the left primary motor cortex (M1).
• Measurement of transcranial magnetic stimulation-evoked electroencephalography (TMS-EEG) parameters (TEPs, EOR, PSI) before and after stimulation.

Main Results:

• Significant "cTBS condition × time" interaction effects were observed in theta and gamma bands of evoked oscillatory responses (EOR) and interhemisphere/global phase synchronization index (PSI).
• Real cTBS significantly increased EOR energy in theta and gamma bands compared to pre-stimulation.
• Real cTBS significantly increased interhemisphere and global PSI, indicating enhanced cortical functional connectivity.

Conclusions:

• cTBS modulation significantly increases EOR and PSI in contralateral brain regions.
• This enhancement of cortical excitability and functional connectivity supports cTBS as a neuromodulation strategy for stroke patients.
• The findings provide a theoretical foundation for applying cTBS in motor rehabilitation.