New complexity measures reveal that topographic loops of human alpha phase potentials are more complex in drowsy than in wake

Kalauzi, A., Vuckovic, A. and Bojić, T. (2018) New complexity measures reveal that topographic loops of human alpha phase potentials are more complex in drowsy than in wake. Medical and Biological Engineering and Computing, 56(6), pp. 967-978. (doi: 10.1007/s11517-017-1746-3) (PMID:29110182)

Abstract

A number of measures, stemming from nonlinear dynamics, exist to estimate complexity of biomedical objects. In most cases they are appropriate, but sometimes unconventional measures, more suited for specific objects, are needed to perform the task. In our present work, we propose three new complexity measures to quantify complexity of topographic closed loops of alpha carrier frequency phase potentials (CFPP) of healthy humans in wake and drowsy states. EEG of ten adult individuals was recorded in both states, using a 14-channel montage. For each subject and each state, a topographic loop (circular directed graph) was constructed according to CFPP values. Circular complexity measure was obtained by summing angles which directed graph edges (arrows) form with the topographic center. Longitudinal complexity was defined as the sum of all arrow lengths, while intersecting complexity was introduced by counting the number of intersections of graph edges. Wilcoxon’s signed-ranks test was used on the sets of these three measures, as well as on fractal dimension values of some loop properties, to test differences between loops obtained in wake vs. drowsy. While fractal dimension values were not significantly different, longitudinal and intersecting complexities, as well as anticlockwise circularity, were significantly increased in drowsy.

• Item Type: Articles
• Additional Information: This work was financed by the Ministry of Education, Science and Technological Development of the Republic of Serbia (projects OI 173022 and III 41028).
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Vuckovic, Dr Aleksandra
• Authors: Kalauzi, A., Vuckovic, A., and Bojić, T.
• College/School: College of Science and Engineering > School of Engineering > Biomedical Engineering
• Journal Name: Medical and Biological Engineering and Computing
• Publisher: Springer
• ISSN: 0140-0118
• ISSN (Online): 1741-0444
• Published Online: 07 November 2017
• Copyright Holders: Copyright © 2017 International Federation for Medical and Biological Engineering
• First Published: First published in Medical and Biological Engineering and Computing 56(6): 967-978
• Publisher Policy: Reproduced in accordance with the publisher copyright policy