G-Guzmán Elvira, Perl Yonatan Sanz, Vohryzek Jakub, Escrichs Anira, Manasova Dragana, Türker Başak, Tagliazucchi Enzo, Kringelbach Morten, Sitt Jacobo D, Deco Gustavo
Department of Information and Communication Technologies, Centre for Brain and Cognition, Computational Neuroscience Group, Universitat Pompeu Fabra, Barcelona, Spain.
Sorbonne Université, Institut du Cerveau - Paris Brain Institute - ICM, Inserm Physiological Investigation of Clinically Normal and Impaired Cognition Team, CNRS, 75013, Paris, France.
Interface Focus. 2023 Apr 14;13(3):20220086. doi: 10.1098/rsfs.2022.0086. eCollection 2023 Jun 6.
Life is a constant battle against equilibrium. From the cellular level to the macroscopic scale, living organisms as dissipative systems require the violation of their detailed balance, i.e. metabolic enzymatic reactions, in order to survive. We present a framework based on temporal asymmetry as a measure of non-equilibrium. By means of statistical physics, it was discovered that temporal asymmetries establish an arrow of time useful for assessing the reversibility in human brain time series. Previous studies in human and non-human primates have shown that decreased consciousness states such as sleep and anaesthesia result in brain dynamics closer to the equilibrium. Furthermore, there is growing interest in the analysis of brain symmetry based on neuroimaging recordings and since it is a non-invasive technique, it can be extended to different brain imaging modalities and applied at different temporo-spatial scales. In the present study, we provide a detailed description of our methodological approach, paying special attention to the theories that motivated this work. We test, for the first time, the reversibility analysis in human functional magnetic resonance imaging data in patients suffering from disorder of consciousness. We verify that the tendency of a decrease in the asymmetry of the brain signal together with the decrease in non-stationarity are key characteristics of impaired consciousness states. We expect that this work will open the way for assessing biomarkers for patients' improvement and classification, as well as motivating further research on the mechanistic understanding underlying states of impaired consciousness.
生命是一场与平衡的持续斗争。从细胞层面到宏观尺度，作为耗散系统的生物体为了生存需要违背其细致平衡，即代谢酶促反应。我们提出了一个基于时间不对称性的框架，以此作为非平衡的一种度量。借助统计物理学发现，时间不对称性确立了一个时间箭头，有助于评估人类大脑时间序列中的可逆性。先前对人类和非人类灵长类动物的研究表明，诸如睡眠和麻醉等意识状态降低会导致大脑动力学更接近平衡。此外，基于神经影像学记录对脑对称性的分析越来越受到关注，并且由于这是一种非侵入性技术，它可以扩展到不同的脑成像模式，并应用于不同的时空尺度。在本研究中，我们详细描述了我们的方法学途径，特别关注推动这项工作的理论。我们首次在患有意识障碍的患者的人类功能磁共振成像数据中测试了可逆性分析。我们证实，脑信号不对称性降低的趋势以及非平稳性的降低是意识受损状态的关键特征。我们期望这项工作将为评估患者改善和分类的生物标志物开辟道路，并激发对意识受损状态背后机制理解的进一步研究。
