Insight into the impact of focal stimulation on large-scale network dynamics

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Computational Neuroscience

Background:

• Brain activity exhibits a hierarchical organization, integrating local circuits into large-scale networks.
• Understanding how focal perturbations affect global brain states is crucial for neural communication and neuromodulation.
• Previous studies often missed dynamic, moment-to-moment fluctuations or focused on pairwise connectivity, neglecting global states.

Purpose of the Study:

• To investigate how focal brain stimulation rapidly alters global brain state dynamics.
• To determine if stimulation of distinct brain regions (DLPFC vs. M1) induces differential changes in brain state dynamics.
• To bridge the gap between focal perturbations and global brain state reconfiguration.

Main Methods:

• Combined transcranial magnetic stimulation (TMS) with electroencephalography (EEG) in 36 healthy participants.
• Utilized microstate analysis to capture global brain state dynamics at millisecond resolution.
• Examined the effects of single-pulse TMS to dorsolateral prefrontal cortex (DLPFC) and primary motor cortex (M1) on EEG microstate dynamics (A-E).

Main Results:

• DLPFC stimulation increased Microstates D and E occurrence and transitions, while suppressing A and B.
• M1 stimulation increased Microstate A occurrence and decreased B occurrence post-pulse.
• Post-pulse microstate dynamics showed significant differences from baseline after DLPFC stimulation compared to M1 stimulation.

Conclusions:

• Focal brain stimulation induces region-specific effects on global brain state dynamics.
• These findings provide a mechanistic basis for neuromodulation strategies targeting site-specific global brain states.
• The results can inform personalized treatments for neuropsychiatric disorders by harnessing targeted brain stimulation effects.