Depression-Related Brain Connectivity Analyzed by EEG Event-Related Phase Synchrony Measure.

Yuezhi Li,Yunfei Zhou,Yong Hu,Xingda Qu,Cheng Kang,Wuyi Wang

doi:10.3389/fnhum.2016.00477

Abstract

This study is to examine changes of functional connectivity in patients with depressive disorder using synchronous brain activity. Event-related potentials (ERPs) were acquired during a visual oddball task in 14 patients with depressive disorder and 19 healthy controls. Electroencephalogram (EEG) recordings were analyzed using event-related phase coherence (ERPCOH) to obtain the functional network. Alteration of the phase synchronization index (PSI) of the functional network was investigated. Patients with depression showed a decreased number of significant electrode pairs in delta phase synchronization, and an increased number of significant electrode pairs in theta, alpha and beta phase synchronization, compared with controls. Patients with depression showed lower target-dependent PSI increment in the frontal-parietal/temporal/occipital electrode pairs in delta-phase synchronization than healthy participants. However, patients with depression showed higher target-dependent PSI increments in theta band in the prefrontal/frontal and frontal-temporal electrode pairs, higher PSI increments in alpha band in the prefrontal pairs and higher increments of beta PSI in the central and right frontal-parietal pairs than controls. It implied that the decrease in delta PSI activity in major depression may indicate impairment of the connection between the frontal and parietal/temporal/occipital regions. The increase in theta, alpha and beta PSI in the frontal/prefrontal sites might reflect the compensatory mechanism to maintain normal cognitive performance. These findings may provide a foundation for a new approach to evaluate the effectiveness of therapeutic strategies for depression.

Highlights

There are many treatment modalities and available pharmacotherapies for depressive disorders
Because there were a few resting-state EEG studies that revealed increased functional connectivity in patients with depression (Fingelkurts et al, 2007; Leuchter et al, 2012), we proposed a hypotheses of functional connectivity disorganization during attentional processes in major depression, and we expected that the disorganization of brain connectivity in major depression provides a new interpretation and assessment of P300 alterations during the target detection process
The main decrease in P300 at parietal sites in the Event-related potentials (ERPs) wave of patients with depressive disorder was found in the delta band, while the main increase in P300 at frontal sites in the ERP wave of patients with depressive disorder was found in the other three frequency bands

Summary

Introduction

There are many treatment modalities and available pharmacotherapies for depressive disorders. It would significantly benefit the clinicians in terms of selecting the most appropriate treatment if there is a clear and sensitive measurement to show the efficiency during treatment initiation. Major depression is believed to alter the brain activity in thalamocortical and corticocortical circuits. Measurement of event-related potentials (ERPs) has been widely used to investigate the cognitive process in patients with depressive disorders. Depression-Related Brain Connectivity leads to a decrease in P300 amplitude in response to target stimuli in oddball tasks. Further studies are required to explore differences in functional connectivity between patients with depression and controls in cognitive tasks

Methods

Results

Discussion

Conclusion