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

Tien-Wen Lee; Gerald Tramontano; Tien-Wen Lee; Gerald Tramontano

doi:10.3934/Neuroscience.2024026

AIMS Neuroscience

2024, Volume 11, Issue 4: 439-448. doi: 10.3934/Neuroscience.2024026

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Brief report

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

Tien-Wen Lee ,
Gerald Tramontano ^,

The NeuroCognitive Institute (NCI) Clinical Research Foundation, NJ 07856, US
Running Title: Connectivity changes to 5-Hz tACS

Received: 08 August 2024 Revised: 27 September 2024 Accepted: 12 October 2024 Published: 18 October 2024

Transcranial alternating current stimulation (tACS) at 5-Hz to the right hemisphere can alleviate anxiety symptoms. We aimed to explore the connectivity changes following the treatment. We collected electroencephalography (EEG) data from 24 participants with anxiety disorders before and after the tACS treatment during a single session. Electric stimulation was applied over the right hemisphere, with 1.0 mA at F4, 1.0 mA at P4, and 2.0 mA at T8, following the 10-10 EEG convention. With eLORETA, the scalp signals were transformed into the cortex's current source density. We assessed the connectivity changes at theta frequency between the centers of Brodmann area (BA) 6/8 (frontal), BA 39/40 (parietal), and BA 21 (middle temporal). Functional connectivity was indicated by lagged coherences and lagged phase synchronization. Paired t-tests were used to quantify the differences statistically. We observed enhanced lagged phase synchronization at theta frequency between the frontal and parietal regions (P = 0.002) and between the parietal and temporal regions (P = 0.005) after Bonferroni correction. Applying tACS 5-Hz over the right hemisphere enhanced inter-regional interaction, which was spectrum-specific and mainly mediated by phase rather than power synchrony. The potential neural mechanisms are discussed.
Citation: Tien-Wen Lee, Gerald Tramontano. Connectivity changes following transcranial alternating current stimulation at 5-Hz: an EEG study[J]. AIMS Neuroscience, 2024, 11(4): 439-448. doi: 10.3934/Neuroscience.2024026

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Abstract

Transcranial alternating current stimulation (tACS) at 5-Hz to the right hemisphere can alleviate anxiety symptoms. We aimed to explore the connectivity changes following the treatment. We collected electroencephalography (EEG) data from 24 participants with anxiety disorders before and after the tACS treatment during a single session. Electric stimulation was applied over the right hemisphere, with 1.0 mA at F4, 1.0 mA at P4, and 2.0 mA at T8, following the 10-10 EEG convention. With eLORETA, the scalp signals were transformed into the cortex's current source density. We assessed the connectivity changes at theta frequency between the centers of Brodmann area (BA) 6/8 (frontal), BA 39/40 (parietal), and BA 21 (middle temporal). Functional connectivity was indicated by lagged coherences and lagged phase synchronization. Paired t-tests were used to quantify the differences statistically. We observed enhanced lagged phase synchronization at theta frequency between the frontal and parietal regions (P = 0.002) and between the parietal and temporal regions (P = 0.005) after Bonferroni correction. Applying tACS 5-Hz over the right hemisphere enhanced inter-regional interaction, which was spectrum-specific and mainly mediated by phase rather than power synchrony. The potential neural mechanisms are discussed.

Acknowledgments

This work was supported by NeuroCognitive Institute (NCI) and NCI Clinical Research Foundation Inc. We would like to thank Almeida Sergio for helping prepare the research material.

Financial support

N/A.

Statements and declarations

Both authors declare no conflicts of interest.

Compliance with ethical standards

This research analyzed the databank collected from 2018 to 2022. The authors assert that all procedures contributing to this work comply with the ethical standards of the relevant national and institutional committees on human experimentation and with the Helsinki Declaration of 1975, as revised in 2008.

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