Altered activation in sensorimotor network after applying rTMS over the primary motor cortex at different frequencies

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Brain Stimulation

Background:

• Repetitive transcranial magnetic stimulation (rTMS) modulates brain activity in sensorimotor networks.
• The specific effects of different rTMS frequencies on this network are not fully understood.

Purpose of the Study:

• To investigate how different frequencies of rTMS applied to the primary motor cortex (M1) alter sensorimotor network activation.
• To compare the effects of high-frequency (HF) and low-frequency (LF) rTMS on brain activity during a finger-tapping task.

Main Methods:

• Utilized functional magnetic resonance imaging (fMRI) combined with a finger-tapping task in 45 healthy participants.
• Participants received either HF (3 Hz), LF (1 Hz), or SHAM rTMS over the left M1.
• Measured percentage signal change (PSC) in predefined sensorimotor network regions of interest (ROIs) before and after rTMS.

Main Results:

• High-frequency (HF) rTMS led to increased activation in the primary motor cortex (M1).
• Low-frequency (LF) rTMS resulted in decreased activation in the primary sensory cortex (S1), ventral premotor cortex (PMv), supplementary motor cortex (SMA), and putamen.
• Activation in SMA, dorsal premotor cortex (PMd), and putamen was higher in the HF group compared to the LF group post-stimulation.

Conclusions:

• Sensorimotor network activation changes are frequency-dependent following rTMS.
• Findings enhance understanding of rTMS effects on brain activity in healthy individuals.
• Results may inform the therapeutic application of rTMS for neurological conditions.