Impaired functional connectivity at EEG alpha and theta frequency bands in major depression

Abstract

Recent reports on functional brain imaging in major depression have lead to an assumption that observed psychopathology might be related to an altered brain functional connectivity. Our hypothesis was that an increase in brain functional connectivity occurs in major depression. As a measure of functional connectivity, the electroencephalogram (EEG) structural synchrony approach was used in 12 medication-free depressive outpatients and 10 control subjects. Differences in the number and strength of structurally synchronized EEG patterns were compared between groups. In depressive patients the number and strength of short cortex functional connections were significantly larger for the left than for the right hemisphere, while the number and strength of long functional connections were significantly larger for the right than for the left hemisphere. Some of the functional connections were positively correlated with the severity of depression, thus being predictive. These were short-range anterior, posterior, and left hemisphere functional connections for the alpha frequency band and short-range anterior functional connections for the theta frequency band. The topology of the most representative functional connections among all patients with major depression indicated that the right anterior and left posterior brain parts may discriminate depressive patients from healthy controls. The obtained data support our hypothesis that there is an increase in brain functional connectivity in major depression. This finding was interpreted within the semantic framework, where different specialization of left (monosemantic context) and right (polysemantic context) hemispheres is functionally insufficient in patients with depression.

EEG Power Asymmetry and Functional Connectivity as a Marker of Treatment Effectiveness in DBS Surgery for Depression

“…Recent studies on a host of neurological disorders including Alzheimer's disease (de Haan et al, 2012;Tahaei et al, 2012), Parkinson disease (Babiloni et al, 2011;Bosboom et al, 2009;Stoffers et al, 2008), schizophrenia (Hanslmayr et al, 2012;Hinkley et al, 2011;Jalili et al, 2007) and epileptic seizures (Mormann et al, 2003;Stam et al, 2007a) have demonstrated a disruption in this synchronization in various frequency bands. In MDD, impairments in synchronization in both y and a bands have been reported (Fingelkurts et al, 2007;LinkenkaerHansen et al, 2005).…”

“…Furthermore, these studies have used different approaches and methodologies to investigate differences in brain dynamics between depressed patients and healthy controls making it difficult to compare outcomes. For example, Lee et al (2011) used correlations between power series of channel pairs as a measure of connectivity; Leistedt et al (2009) used synchronization likelihood (Stam et al, 2003); whereas Fingelkurts et al (2007) used an in-house synchronization measure termed index of structural synchronization (Fingelkurts and Kahkonen, 2005). Although these and other EEG/MEG measures of connectivity (phase coherency, phase lag index, imaginary coherency, etc) have been shown to capture aspects of correlations/synchronization between two time series, they are known to perform differently.…”

Chronic deep brain stimulation of the rat ventral medial prefrontal cortex disrupts hippocampal–prefrontal coherence

“…Previous work using electroencephalograms (EEGs) to examine inter-region coherence in depressed versus control patients have yielded complex results, with differences found in the proximity of electrode pairs, their hemisphere, and frequency bands (Fingelkurts et al, 2007;Leuchter et al, 2012). The effects on EEG of treatment with SCG DBS are also complex, although generally appear to make depressed brains appear more similar to nondepressed controls (Broadway et al, 2012;Quraan et al, 2014).…”

Eeg spectral characteristics in resistant depression patients on transcranial magnetic stimulation treatment

“…В большин-стве так называемых нейрофизиологических или электро-энцефалографических моделях депрессии в качестве од-ного из облигатных признаков описывается наличие функциональной асимметрии передних отделов мозга, в том числе префронтальных, со снижением биоэлектиче-ской активности этих областей левого полушария [24][25][26]. Эти изменения в определенной степени сохраняются у пациентов с депрессией и в эутимном состоянии [27][28][29]. Достаточно распространенной является гипотеза о наличии особого «нейрофизиологического диатеза» у лиц с высоким риском развития депрессии в течение жизни [29].…”

“…Эти изменения в определенной степени сохраняются у пациентов с депрессией и в эутимном состоянии [27][28][29]. Достаточно распространенной является гипотеза о наличии особого «нейрофизиологического диатеза» у лиц с высоким риском развития депрессии в течение жизни [29]. Он характеризуется нарушением непрямых функцио-нальных нейрональных связей в левых передних областях мозга и проявляется снижением функциональной актив-ности ЭЭГ в этих регионах [24,29].…”