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Schizophr Bull. 2015 Jul;41(4):930-9. doi: 10.1093/schbul/sbu121. Epub 2014 Aug 28.

Increased Resting-State Gamma-Band Connectivity in First-Episode Schizophrenia.

Author information

1
Department of Psychiatry and Psychotherapy, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; c.andreou@uke.de.
2
Department of Neurophysiology and Pathophysiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany;
3
Department of Psychiatry and Psychotherapy, University Medical Center Hamburg-Eppendorf, Hamburg, Germany;
4
Developmental Neurophysiology, Institute of Neuroanatomy, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.

Abstract

BACKGROUND:

Schizophrenia has long been suggested to represent a disorder with prominent neural dysconnectivity. Gamma-band oscillations are highly relevant in this context, due both to their proposed involvement in neuronal synchronization and to their association with neurotransmitter systems relevant for schizophrenia. Several task-related studies have confirmed reduced power and synchronization of gamma-band oscillations in schizophrenia, but it has been suggested that these findings might not apply to the resting state. The present study aimed to investigate resting-state gamma-band connectivity in patients with schizophrenia.

METHODS:

Sixty-four channel resting-state electroencephalography (eyes closed) was recorded in 22 patients with first-episode schizophrenia and 22 healthy controls matched for age and gender. Orthogonalized power envelope correlation was used as a measure of connectivity across 80 cortical regions at 40 Hz. Mean connectivity at each region was compared across groups using the nonparametric randomization approach. Additionally, the network-based statistic was applied to identify affected networks in patients.

RESULTS:

Patients displayed increased mean functional gamma-band connectivity compared to controls in the left rolandic operculum. Network-based analyses indicated increased connectivity in patients within a strongly lateralized network consisting mainly of left inferior frontal/orbitofrontal, lateral and medial temporal, and inferior parietal areas. Within this network, gamma-band connectivity was higher in patients with low positive and disorganization symptom levels.

CONCLUSIONS:

The present study provides a link between resting-state gamma-band connectivity and the core symptoms of schizophrenia. The observed findings are different than those reported by task-related studies, suggesting that resting-state studies might reveal new aspects in the pathophysiology of schizophrenia.

KEYWORDS:

EEG; disorganization; functional connectivity; positive symptoms; power envelope correlation; psychosis

PMID:
25170031
PMCID:
PMC4466170
DOI:
10.1093/schbul/sbu121
[Indexed for MEDLINE]
Free PMC Article

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