Next Article in Journal
Projected Affinity Values for Nyström Spectral Clustering
Next Article in Special Issue
Causal Shannon–Fisher Characterization of Motor/Imagery Movements in EEG
Previous Article in Journal
Microstructure and Mechanical Properties of Particulate Reinforced NbMoCrTiAl High Entropy Based Composite
Previous Article in Special Issue
Complexity Changes in Brain Activity in Healthy Ageing: A Permutation Lempel-Ziv Complexity Study of Magnetoencephalograms
Open AccessArticle

Topographic Reconfiguration of Local and Shared Information in Anesthetic-Induced Unconsciousness

1
Department of Anesthesiology, Center for Consciousness Science, University of Michigan Medical School, Ann Arbor, MI 48109, USA
2
Department of Radiology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
*
Authors to whom correspondence should be addressed.
Entropy 2018, 20(7), 518; https://doi.org/10.3390/e20070518
Received: 18 May 2018 / Revised: 1 July 2018 / Accepted: 2 July 2018 / Published: 10 July 2018
(This article belongs to the Special Issue Permutation Entropy & Its Interdisciplinary Applications)
Theoretical consideration predicts that the alteration of local and shared information in the brain is a key element in the mechanism of anesthetic-induced unconsciousness. Ordinal pattern analysis, such as permutation entropy (PE) and symbolic mutual information (SMI), have been successful in quantifying local and shared information in neurophysiological data; however, they have been rarely applied to altered states of consciousness, especially to data obtained with functional magnetic resonance imaging (fMRI). PE and SMI analysis, together with the superb spatial resolution of fMRI recording, enables us to explore the local information of specific brain areas, the shared information between the areas, and the relationship between the two. Given the spatially divergent action of anesthetics on regional brain activity, we hypothesized that anesthesia would differentially influence entropy (PE) and shared information (SMI) across various brain areas, which may represent fundamental, mechanistic indicators of loss of consciousness. FMRI data were collected from 15 healthy participants during four states: wakefulness (W), light (conscious) sedation (L), deep (unconscious) sedation (D), and recovery (R). Sedation was produced by the common, clinically used anesthetic, propofol. Firstly, we found that that global PE decreased from W to D, and increased from D to R. The PE was differentially affected across the brain areas; specifically, the PE in the subcortical network was reduced more than in the cortical networks. Secondly, SMI was also differentially affected in different areas, as revealed by the reconfiguration of its spatial pattern (topographic structure). The topographic structures of SMI in the conscious states W, L, and R were distinctively different from that of the unconscious state D. Thirdly, PE and SMI were positively correlated in W, L, and R, whereas this correlation was disrupted in D. And lastly, PE changes occurred preferentially in highly connected hub regions. These findings advance our understanding of brain dynamics and information exchange, emphasizing the importance of topographic structure and the relationship of local and shared information in anesthetic-induced unconsciousness. View Full-Text
Keywords: permutation entropy; functional magnetic resonance image; mutual information; functional connectivity; anesthesia; consciousness permutation entropy; functional magnetic resonance image; mutual information; functional connectivity; anesthesia; consciousness
Show Figures

Figure 1

MDPI and ACS Style

Lee, H.; Huang, Z.; Liu, X.; Lee, U.; Hudetz, A.G. Topographic Reconfiguration of Local and Shared Information in Anesthetic-Induced Unconsciousness. Entropy 2018, 20, 518.

Show more citation formats Show less citations formats
Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Article Access Map

1
Back to TopTop