Short-lived Alpha Power Suppression Induced by Low-intensity Arrhythmic rTMS

Area of Science:

• Neuroscience
• Electrophysiology
• Brain Stimulation

Background:

• Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive brain stimulation technique.
• Understanding the parameters influencing rTMS aftereffects is crucial for therapeutic applications.
• Scalp electroencephalography (EEG) measures brain activity, including alpha power, which is sensitive to stimulation.

Purpose of the Study:

• To investigate the role of electric field strength in rTMS-induced aftereffects on resting-state EEG.
• To compare the effects of rhythmic and arrhythmic rTMS protocols on alpha power.
• To determine the duration and characteristics of rTMS aftereffects.

Main Methods:

• Two experiments involving 32 participants applying rTMS over the left parietal-occipital region.
• Electric field simulations guided stimulation intensity (20-50 mV/mm).
• Rhythmic and arrhythmic rTMS bursts were applied, with a sham rTMS control group. Alpha power changes were measured in inter-burst intervals (0.2-10s post-rTMS).

Main Results:

• Aftereffects, characterized by alpha power suppression, lasted up to 2 seconds at ~35 mV/mm.
• Arrhythmic rTMS significantly reduced alpha power relative to baseline.
• No significant long-term differences were observed between rhythmic and arrhythmic or rhythmic and sham protocols.

Conclusions:

• Weak arrhythmic rTMS can induce short-lived alpha suppression.
• The pattern of rTMS stimulation (rhythmic vs. arrhythmic) influences immediate aftereffects.
• Electric field strength plays a role in the magnitude and duration of rTMS-induced EEG changes.