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. 2022 Feb:134:50-64.
doi: 10.1016/j.clinph.2021.12.002. Epub 2021 Dec 11.

A method to assess the default EEG macrostate and its reactivity to stimulation

Cosmin-Andrei Serban  1 , Andrei Barborica  2 , Adina-Maria Roceanu  3 , Ioana Mindruta  4 , Jan Ciurea  5 , Alexandru C Pâslaru  6 , Ana-Maria Zăgrean  6 , Leon Zăgrean  6 , Mihai Moldovan  7
Affiliations

A method to assess the default EEG macrostate and its reactivity to stimulation

Cosmin-Andrei Serban et al. Clin Neurophysiol. 2022 Feb.

Abstract

Objective: The default mode network (DMN) is deactivated by stimulation. We aimed to assess the DMN reactivity impairment by routine EEG recordings in stroke patients with impaired consciousness.

Methods: Binocular light flashes were delivered at 1 Hz in 1-minute epochs, following a 1-minute baseline (PRE). The EEG was decomposed in a series of binary oscillatory macrostates by topographic spectral clustering. The most deactivated macrostate was labeled the default EEG macrostate (DEM). Its reactivity (DER) was quantified as the decrease in DEM occurrence probability during stimulation. A normalized DER index (DERI) was calculated as DER/PRE. The measures were compared between 14 healthy controls and 32 comatose patients under EEG monitoring following an acute stroke.

Results: The DEM was mapped to the posterior DMN hubs. In the patients, these DEM source dipoles were 3-4 times less frequent and were associated with an increased theta activity. Even in a reduced 6-channel montage, a DER below 6.26% corresponding to a DERI below 0.25 could discriminate the patients with sensitivity and specificity well above 80%.

Conclusion: The method detected the DMN impairment in post-stroke coma patients.

Significance: The DEM and its reactivity to stimulation could be useful to monitor the DMN function at bedside.

Keywords: Default mode network; EEG reactivity; Macrostate; Reactivity index.

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Conflict of interest statement

Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: The authors working with Termobit Prod SRL RO during this project were disclosed in the affiliations. AB and CS are shareholders at Termobit Prod Srl. The research grant structure required that the private partner, Termobit Prod, partially fund their own activities. MM was PI and was funded only through grant funds awarded to Termobit, without having a commercial interest in the company. All other authors involved in this study, representing public institutions (AMR, IRM, JC, ACP, AMZ, LZ) were funded from grant funds and have no stock interest or consultancies with Termobit Prod or FHC, Inc. Authors have filed a patent proposal for the presented method.

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