Altered resting-state EEG source functional connectivity in schizophrenia: the effect of illness duration

Abstract

Despite the increasing body of evidence supporting the hypothesis of schizophrenia as a disconnection syndrome, studies of resting-state EEG Source Functional Connectivity (EEG-SFC) in people affected by schizophrenia are sparse. The aim of the present study was to investigate resting-state EEG-SFC in 77 stable, medicated patients with schizophrenia (SCZ) compared to 78 healthy volunteers (HV). In order to study the effect of illness duration, SCZ were divided in those with a short duration of disease (SDD; n = 25) and those with a long duration of disease (LDD; n = 52). Resting-state EEG recordings in eyes closed condition were analyzed and lagged phase synchronization (LPS) indices were calculated for each ROI pair in the source-space EEG data. In delta and theta bands, SCZ had greater EEG-SFC than HV; a higher theta band connectivity in frontal regions was observed in LDD compared with SDD. In the alpha band, SCZ showed lower frontal EEG-SFC compared with HV whereas no differences were found between LDD and SDD. In the beta1 band, SCZ had greater EEG-SFC compared with HVs and in the beta2 band, LDD presented lower frontal and parieto-temporal EEG-SFC compared with HV. In the gamma band, SDD had greater connectivity values compared with LDD and HV. This study suggests that resting state brain network connectivity is abnormally organized in schizophrenia, with different patterns for the different EEG frequency components and that EEG can be a powerful tool to further elucidate the complexity of such disordered connectivity.

Increased Resting State Triple Network Functional Connectivity in Undergraduate Problematic Cannabis Users: A Preliminary EEG Coherence Study

“…At least 3 minutes of clean EEG data (not necessarily consecutive) were selected and analyzed for each subject. According to previous exact Low-Resolution Electromagnetic Tomography software (eLORETA) studies [43,45,[62][63][64][65][66], artifact-free data were fragmented into epochs of 2 seconds for the EEG coherence analysis.…”

Graph Signal Processing of Low and High-Order Dynamic Functional Connectivity Networks Using EEG Resting-State for Schizophrenia: A Whole Brain Breakdown

“…Evidences that contradict have been reported in fast oscillations at β (13-30 Hz) and γ frequencies at rest, including both elevated (Di Lorenzo, et al, 2015), reduced (Kam et al, 2013) and intact (Lehmann et al, 2014, Andreou et al, 2015, Tauscher et al,1998, Winterer et al, 2011 β frequency band connectivity. Preliminary evidence suggests that β based functional connectivity is influenced by illness progression and clinical symptomatology (Di Lorenzo, et al, 2015). For a systematic review tailored to functional connectivity evidences using EEG in schizophrenia see (Maran et al, 2016).…”

“…Interestingly, two studies reported a high correlation between functional connectivity at rest in α frequency band with symptoms in ScZ (Hinkley et al, 2011 ;Merrin and Floyd, 1996). Evidences that contradict have been reported in fast oscillations at β (13-30 Hz) and γ frequencies at rest, including both elevated (Di Lorenzo, et al, 2015), reduced (Kam et al, 2013) and intact (Lehmann et al, 2014, Andreou et al, 2015, Tauscher et al,1998, Winterer et al, 2011 β frequency band connectivity. Preliminary evidence suggests that β based functional connectivity is influenced by illness progression and clinical symptomatology (Di Lorenzo, et al, 2015).…”

“…The majority of studies that explored functional connectivity at α frequency band reported a decreased patter in ScZ. In particular, decreased α connectivity estimated by coherence, lagged coherence and phase synchrony, has been reported at frontal (Di Lorenzo, et al, 2015 ;Tauscher et al,1998), fronto-posterior (Di Lorenzo, et al, 2015, Lehmann et al, 2014 and parieto-temporal (Di Lorenzo, et al, 20150 brain areas (for different results see also Andreou et al, 2015, Kam et al, 2013, Winterer et al, 2011, Merrin and Floyd, 1996. Interestingly, two studies reported a high correlation between functional connectivity at rest in α frequency band with symptoms in ScZ (Hinkley et al, 2011 ;Merrin and Floyd, 1996).…”

Reduced interhemispheric and increased intrahemispheric connectivity in schizophrenia brain networks

“…Deficits in the auditory system have been associated with schizophrenia (Pfefferbaum et al, 1989;Polich, 2007;Roach and Mathalon, 2008;Mathalon et al, 2010;Decoster et al, 2012;Näätänen et al, 2012;Nagai et al, 2013;Bartha-Doering et al, 2015;Thibaut et al, 2015;Javitt and Sweet, 2015;Schall, 2016). Differences in cognitive processing have been revealed in visual paradigms too (Bestelmeyer, 2012;Oribe et al, 2014;Farkas et al, 2015), as well as during resting state (Greicius, 2008;Alonsosolís et al, 2015;Di Lorenzo et al, 2015). Quantifying the EEG amplitude during attentional tasks even allowed to identify patients with schizophrenia versus controls in 84.7 % of cases (Laton et al, 2014).…”