Original Research ARTICLE
Electroconvulsive therapy modulates resting-state EEG oscillatory pattern and phase synchronization in nodes of the default mode network in patients with depressive disorder
- 1Department of Neuropsychiatry, School of Medicine, Keio University, Japan
Introduction: Electroconvulsive therapy (ECT) has antidepressant effects, but it also has possible cognitive side effects. The effects of ECT on neuronal oscillatory pattern and phase synchronization, and the relationship between clinical response or cognitive change and EEG measurements remain elusive.
Methods: Individuals with unipolar depressive disorder receiving bilateral ECT were recruited. Five minutes of resting, eyes-closed, 19-lead EEG recordings were obtained before and after a course of ECT. Non-overlapping 60 artifact-free epocs of 2-s duration were used for the analyses. We used exact Low Resolution Electromagnetic Tomography (eLORETA) to compute the whole-brain three-dimensional intracortical distribution of current source density (CSD) and phase synchronization among 28 regions-of-interest (ROIs). Paired t-tests were used to identify cortical voxels and connectivities showing changes after ECT. Montgomery Asberg Depression Rating Scale (MADRS) and Mini-Mental State Examination (MMSE) were used to evaluate the severity of depression and the global cognitive function. Correlation analyses were conducted to identify the relationship between changes in the EEG measurements and changes in MADRS or MMSE.
Results: Thirteen depressed patients (5 females, mean age: 58.4 years old) were included. ECT increased theta CSD in the anterior cingulate cortex, and decreased beta CSD in the frontal pole, and gamma CSD in the inferior parietal lobule. ECT increased theta phase synchronization between the posterior cingulate cortex (PCC) and the anterior frontal cortex, and decreased beta phase synchronization between the PCC and temporal regions. A decline in beta synchronization in the left hemisphere was associated with cognitive changes after ECT.
Conclusions: ECT modulated resting-state EEG oscillatory patterns and phase synchronization in central nodes of the default mode network (DMN). Changes in beta synchronization in the left hemisphere might explain the ECT-related cognitive side effects.
Keywords: Electroconvulsive therapy (ECT), Electroencephalography (EEG), Depressive Disorder, Low resolution electromagnetic tomography (LORETA), Current source density (CSD), phase synchronization
Received: 21 Nov 2018;
Accepted: 03 Jan 2019.
Edited by:Keiichiro Nishida, Kansai Medical University, Japan
Reviewed by:Yasunori Aoki, Department of Psychiatry, Osaka University Graduate School of Medicine
Hidetoshi Takahashi, National Center of Neurology and Psychiatry (Japan), Japan
Copyright: © 2019 Takamiya, Hirano, Yamagata, Takei, Kishimoto and Mimura. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Dr. Jinichi Hirano, Department of Neuropsychiatry, School of Medicine, Keio University, Tokyo, 160-8582, Japan, firstname.lastname@example.org