Lee UnCheol, Blain-Moraes Stefanie, Mashour George A
Center for Consciousness Science, University of Michigan Medical School, 1150 West Medical Center Drive, Ann Arbor, MI 48105, USA
Department of Anesthesiology, University of Michigan Medical School, 1150 West Medical Center Drive, Ann Arbor, MI 48105, USA.
Philos Trans A Math Phys Eng Sci. 2015 Feb 13;373(2034). doi: 10.1098/rsta.2014.0117.
'Covert consciousness' is a state in which consciousness is present without the capacity for behavioural response, and it can occur in patients with intraoperative awareness or unresponsive wakefulness syndrome. To detect and prevent this undesirable state, it is critical to develop a reliable neurobiological assessment of an individual's level of consciousness that is independent of behaviour. One such approach that shows potential is measuring surrogates of cortical communication in the brain using electroencephalography (EEG). EEG is practicable in clinical application, but involves many fundamental signal processing problems, including signal-to-noise ratio and high dimensional complexity. Symbolic analysis of EEG can mitigate these problems, improving the measurement of brain connectivity and the ability to successfully assess levels of consciousness. In this article, we review the problem of covert consciousness, basic neurobiological principles of consciousness, current methods of measuring brain connectivity and the advantages of symbolic processing, with a focus on symbolic transfer entropy (STE). Finally, we discuss recent advances and clinical applications of STE and other symbolic analyses to assess levels of consciousness.
“隐性意识”是一种意识存在但无行为反应能力的状态，它可能出现在术中知晓或无反应觉醒综合征患者身上。为了检测和预防这种不良状态，开发一种独立于行为的可靠的个体意识水平神经生物学评估方法至关重要。一种显示出潜力的方法是使用脑电图（EEG）测量大脑中皮质通信的替代指标。EEG在临床应用中可行，但涉及许多基本的信号处理问题，包括信噪比和高维复杂性。EEG的符号分析可以减轻这些问题，改善大脑连通性的测量以及成功评估意识水平的能力。在本文中，我们回顾了隐性意识问题、意识的基本神经生物学原理、当前测量大脑连通性的方法以及符号处理的优势，重点是符号转移熵（STE）。最后，我们讨论了STE和其他符号分析在评估意识水平方面的最新进展和临床应用。
