Mapping shared and specific cortical after-effects of repetitive TMS on brain function.

Area of Science:

• Neuroscience
• Brain Stimulation
• Cognitive Science

Background:

• Repetitive transcranial magnetic stimulation (rTMS) is a common tool for modulating brain activity.
• Understanding how different rTMS protocols affect cortical function and shared principles is unclear.

Purpose of the Study:

• To map changes in local hemodynamic fluctuations after various rTMS protocols.
• To identify common principles underlying rTMS effects across different stimulation strategies.

Main Methods:

• Resting-state fMRI was used before and after single-session rTMS.
• Nine distinct rTMS protocols targeting specific cortical regions were employed.
• Changes in the local amplitude of hemodynamic fluctuations were comprehensively mapped.

Main Results:

• rTMS after-effects varied across protocols but were constrained by structural and functional connectivity.
• A shared spatial pattern aligned with the brain's sensory-association hierarchy emerged across all protocols.
• Effects corresponded with neurotransmitter systems and cognitive domains, particularly from parietal and motor regions, suggesting the parietal cortex as a transdiagnostic target. Results were replicated in multi-session rTMS datasets.

Conclusions:

• A unified framework for rTMS after-effects exists, based on cortical hierarchy, neurochemistry, and cognitive activations.
• Findings offer guidance for optimizing neuromodulation strategies in brain disorders.
• The parietal cortex shows potential as a transdiagnostic target for rTMS therapy.