Page 285 - MEGIN Book Of Abstracts - 2023

hypothesized to be a 'dysconnection' syndrome due to Auditory driven gamma synchrony is associated
abnormal neural network formation. Although numer- with cortical thickness in widespread cortical areas
ous studies have helped elucidate the pathophysiol- (2022)
ogy of SZ, many aspects of the mechanism underlying
psychotic symptoms remain unknown. This study used Schuler, Anna-Lisa; Ferrazzi, Giulio; Colenbier, Nigel;
graph theory analysis to evaluate the characteristics of Arcara, Giorgio; Piccione, Francesco; Ferreri, Florinda;
the resting-state network (RSN) in terms of microscale Marinazzo, Daniele; Pellegrino, Giovanni
and macroscale indices, and to identify candidates as
potential biomarkers of SZ. Specifically, we discriminat- IRCCS San Camillo Hospital, Via Alberoni 70, Venice 30126,
ed topological characteristics in the frequency domain Italy. Electronic address: annalisa.schuler@hsancamillo.it;
and investigated them in the context of psychotic Rehabilitation, University of Padua, Italy; Unit of Neurology,
symptoms in patients with SZ. Unit of Clinical Neurophysiology, Study Center of Neurode-
generation (CESNE), Department of Neuroscience, University
METHODS We performed graph theory analysis of of Padua, Padua, Italy; Department of Clinical Neurophysiol-
electrophysiological RSN data using magnetoencepha- ogy, Kuopio University Hospital, University of Eastern Finland,
lography to compare topological characteristics repre- Kuopio, Finland; Department of Data Analysis, Faculty of
sented by microscale (degree centrality and clustering Psychology and Educational Sciences, Ghent University
coefficient) and macroscale (global efficiency, local
efficiency, and small-worldness) indices in 29 patients OBJECTIVE Gamma synchrony is a fundamental func-
with SZ and 38 healthy controls. In addition, we inves- tional property of the cerebral cortex, impaired in mul-
tigated the aberrant topological characteristics of the tiple neuropsychiatric conditions (i.e. schizophrenia,
RSN in patients with SZ and their relationship with SZ Alzheimer's disease, stroke etc.). Auditory stimulation in
symptoms. the gamma range allows to drive gamma synchrony of
the entire cortical mantle and to estimate the efficiency
RESULTS SZ was associated with a decreased clustering of the mechanisms sustaining it. As gamma synchrony
coefficient, local efficiency, and small-worldness, es- depends strongly on the interplay between parvalbu-
pecially in the high beta band. In addition, macroscale min-positive interneurons and pyramidal neurons, we
changes in the low beta band are closely associated hypothesize an association between cortical thickness
with negative symptoms. and gamma synchrony. To test this hypothesis, we em-
ployed a combined magnetoencephalography (MEG)
CONCLUSIONS The local networks of patients with SZ - Magnetic Resonance Imaging (MRI) study.
may disintegrate at both the microscale and mac-
roscale levels, mainly in the beta band. Adopting an METHODS Cortical thickness was estimated from
electrophysiological perspective of SZ as a failure to anatomical MRI scans. MEG measurements related to
form local networks in the beta band will provide exposure of 40 Hz amplitude modulated tones were
deeper insights into the pathophysiology of SZ as a projected onto the cortical surface. Two measures of
'dysconnection' syndrome. cortical synchrony were considered: (a) inter-trial phase
consistency at 40 Hz, providing a vertex-wise estima-
Keywords: beta band, graph theory, magnetoencephalog- tion of gamma synchronization, and (b) phase-locking
raphy, resting-state network, schizophrenia values between primary auditory cortices and whole
cortical mantle, providing a measure of long-range
Psychiatry and clinical neurosciences (2022), Vol. 76, No. 7 cortical synchrony. A correlation between cortical thick-
(35397141) (0 citations) ness and synchronization measures was then calcu-
lated for 72 MRI-MEG scans.

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