State-dependent tDCS modulation of the somatomotor network: A MEG study.

Area of Science:

• Neuroscience
• Neurophysiology
• Computational Neuroscience

Background:

• Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique used to study brain excitability.
• Variability in brain and behavioral responses to tDCS hinders its clinical application.
• State-dependency is a key factor contributing to tDCS response variability.

Purpose of the Study:

• To investigate the role of state-dependency in modulating brain activity after tDCS.
• To examine how initial brain states influence spectral activity and functional connectivity in somatomotor regions.
• To explore the application of advanced statistical models for analyzing state-dependent tDCS effects.

Main Methods:

• Real and sham tDCS were applied to participants.
• Changes in spectral activity and functional connectivity in somatomotor regions were measured.
• Generalized additive mixed models (GAMMs) were employed to analyze state-dependent modulations.

Main Results:

• Spectral activity changes in somatomotor regions were state-dependent, unlike functional connectivity.
• A non-linear interaction between stimulation condition and initial brain state was observed.
• Reduced alpha and beta power following real tDCS was specific to participants with initially higher power in these bands.

Conclusions:

• State-dependency is crucial for understanding tDCS effects.
• Appropriate statistical modeling can account for state-dependency in tDCS research.
• Findings offer insights into tDCS mechanisms and potential for identifying responders.