Connectivity changes following transcranial alternating current stimulation at 5-Hz: an EEG study.

Area of Science:

• Neuroscience
• Brain Stimulation
• Computational Psychiatry

Background:

• Anxiety disorders are associated with altered brain connectivity.
• Transcranial alternating current stimulation (tACS) is a non-invasive neuromodulation technique.
• Previous studies suggest 5-Hz tACS to the right hemisphere may alleviate anxiety symptoms.

Purpose of the Study:

• To investigate the effects of 5-Hz right-hemisphere tACS on functional brain connectivity in individuals with anxiety disorders.
• To explore changes in theta-frequency connectivity following tACS treatment.

Main Methods:

• Electroencephalography (EEG) data were collected from 24 participants with anxiety disorders before and after a single tACS session.
• tACS was applied over the right hemisphere at 5-Hz.
• Source localization using eLORETA transformed scalp EEG into cortical current source density.
• Functional connectivity was assessed using lagged coherence and lagged phase synchronization in the theta frequency band between frontal, parietal, and temporal regions.

Main Results:

• Significant enhancement in lagged phase synchronization was observed between frontal and parietal regions (P = 0.002) after Bonferroni correction.
• Enhanced lagged phase synchronization was also found between parietal and temporal regions (P = 0.005).
• The observed connectivity changes were specific to the theta frequency band and primarily mediated by phase synchrony.

Conclusions:

• Right-hemisphere 5-Hz tACS effectively enhanced inter-regional brain connectivity in individuals with anxiety disorders.
• The findings suggest that tACS-induced connectivity modulation, particularly in the theta band, may underlie its anxiolytic effects.
• Further research is warranted to elucidate the precise neural mechanisms involved.