Disturbed Connectivity of EEG Functional Networks in Alcoholism: A Graph-Theoretic Analysis

Abstract

Generally, an alcoholic's brain shows explicit damage. However, in cognitive tasks, the correlation between the topological structural changes of the brain networks and the brain damage is still unclear. Scalp electrodes and synchronization likelihood (SL) were applied to the constructions of the EGG functional networks of 28 alcoholics and 28 healthy volunteers. The graph-theoretic analysis showed that in cognitive tasks, compared with the healthy control group, the brain networks of alcoholics had smaller clustering coefficients in β1 bands, shorter characteristic path lengths, increased global efficiency, but similar small-world properties. The abnormal topological structure of the alcoholics may be related to the local-function brain damage and the compensation mechanism adopted to complete tasks. This conclusion provides a new perspective for alcoholrelated brain damage.

Neuropsychophysiological Measures of Alcohol Dependence: Can We Use EEG in the Clinical Assessment?

“…There is also data in EEG studies, low doses of alcohol in social consumers producing higher global efficiency and an increased density in resting alpha, as well as a short characteristic path ( 12 ). Similar observations were made in alcohol-dependent individuals during a working memory task ( 149 ), where smaller characteristic paths, reduced clustering, and an increased global efficiency were found in low beta band. These results might be indicating an altered functioning of network efficiency under the effects of alcohol, as well as a compensating mechanism in response to task demands, in order to carry out cognitive operations.…”

“…To this date, functional connectivity studies in psychiatric conditions are mostly exploratory and have the purpose of characterizing the neural functioning of the brain. In AUD, functional connectivity studies using EEG have found alterations in brain synchronization in several frequency bands (alpha, beta or gamma) ( 132 , 149 , 158 ) and they seem to present a reduced efficiency of communication, although results are somehow scarce and diverse. Nonetheless, prospective studies should be able to offer clearer hypotheses on brain alterations in psychiatric patients, such as AUD, and to help find out if they persist in time or are modulated by different clinical factors.…”

An Increase in Postural Load Facilitates an Anterior Shift of Processing Resources to Frontal Executive Function in a Postural-Suprapostural Task

“…Among the several quantitative approaches, SL was used to characterize the inter-dependences between two cortical activities because it is the most popular index for estimating functional connectivity for neurophysiological data. SL has been widely been used to assess connectivity strength in the graphic based studies using either low-density (Pijnenburg et al, 2004 ; Smit et al, 2012 ; Boersma et al, 2013 ; Liu et al, 2015 ; Herrera-Díaz et al, 2016 ) or high-density EEG (Polanía et al, 2011 ; Cao et al, 2014 ), because SL is able to account for the repertoire of network states, considering linear and nonlinear interactions between multiple synchronized neural sources in the brain (Stam and van Dijk, 2002 ). Also, SL can sensitively detect slight and complex variations in the coupling strength (Koenis et al, 2013 ) and resolve synchronization patterns on a fine time scale (Stam and van Dijk, 2002 ; Betzel et al, 2012 ).…”

Topological structures are consistently overestimated in functional complex networks

“…As an example of application of the proposed methodology, we considered a data set of EEG recordings from a group of alcoholic subjects and matched controls 34 , 35 , freely available at https://archive.ics.uci.edu/ml/datasets/EEG+Database . Each trial corresponds to an object recognition task, as described in 36 ; and its corresponding EEG activity has been recorded during one second, with a 256 Hz (3.9-ms/epoch) sampling rate from 64 electrodes located at standard scalp sites.…”