Attenuated asymmetry of functional connectivity in schizophrenia: A high-resolution EEG study

Authors

  • Mahdi Jalili,

    1. Department of Computer Engineering, Sharif University of Technology, Tehran, Iran
    2. École Polytechnique Fédérale de Lausanne (EPFL), School of Computer and Communication Sciences, IC-LANOS, Lausanne, Switzerland
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  • Reto Meuli,

    1. Department of Radiology, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland
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  • Kim Q. Do,

    1. Center for Psychiatric Neuroscience, Department of Psychiatry, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland
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  • Martin Hasler,

    1. École Polytechnique Fédérale de Lausanne (EPFL), School of Computer and Communication Sciences, IC-LANOS, Lausanne, Switzerland
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  • Timothy J. Crow,

    1. SANE POWIC, University Department of Psychiatry, Warneford Hospital, Oxford, UK
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  • Maria G. Knyazeva

    1. Department of Radiology, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland
    2. Department of Neurology, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland
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  • This work was supported by an Interdisciplinary FBM-UNIL grant to Maria G. Knyazeva and by a Swiss National Science Foundation grant (No. 200020-117975/1) to Mahdi Jalili. We are grateful to Prof. R. S. J. Frackowiak for his help and encouragement, Dr. S. Lavoie for EEG recording, and Ms D. Polzik for assistance in the preparation of the manuscript.

Address reprint requests to: Mahdi Jalili, Department of Computer Engineering, Sharif University of Technology, Azadi Avenue, P.O. Box 11155-9517, Tehran, Iran. E-mail: MJalili@sharif.edu or Maria G. Knyazeva, Department of Neurology, CHUV, Rue du Bugnon 46, 1011 Lausanne, Switzerland. E-mail: Maria.Knyazeva@chuv.ch

Abstract

The interhemispheric asymmetries that originate from connectivity-related structuring of the cortex are compromised in schizophrenia (SZ). Under the assumption that such abnormalities affect functional connectivity, we analyzed its correlate—EEG synchronization—in SZ patients and matched controls. We applied multivariate synchronization measures based on Laplacian EEG and tuned to various spatial scales. Compared to the controls who had rightward asymmetry at a local level (EEG power), rightward anterior and leftward posterior asymmetries at an intraregional level (1st and 2nd order S-estimator), and rightward global asymmetry (hemispheric S-estimator), SZ patients showed generally attenuated asymmetry, the effect being strongest for intraregional synchronization in the alpha and beta bands. The abnormalities of asymmetry increased with the duration of the disease and correlated with the negative symptoms. We discuss the tentative links between these findings and gross anatomical asymmetries, including the cerebral torque and gyrification pattern, in normal subjects and SZ patients.

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