Disorders of consciousness (DoCs) pose a significant clinical and ethical challenge because they allow for complex forms of conscious experience in patients where intentional behaviour and communication are highly limited or non-existent. There is a pressing need for brain-based assessments that can precisely and accurately characterize the conscious state of individual DoC patients. There has been an ongoing research effort to develop neural measures of consciousness. However, these measures are challenging to validate not only due to our lack of ground truth about consciousness in many DoC patients but also because there is an open ontological question about consciousness. There is a growing, well-supported view that consciousness is a multidimensional phenomenon that cannot be fully described in terms of the theoretical construct of hierarchical, easily ordered conscious levels. The multidimensional view of consciousness challenges the utility of levels-based neural measures in the context of DoC assessment. To examine how these measures may map onto consciousness as a multidimensional phenomenon, this article will investigate a range of studies where they have been applied in states other than DoC and where more is known about conscious experience. This comparative evidence suggests that measures of conscious level are more sensitive to some dimensions of consciousness than others and cannot be assumed to provide a straightforward hierarchical characterization of conscious states. Elevated levels of brain complexity, for example, are associated with conscious states characterized by a high degree of sensory richness and minimal attentional constraints, but are suboptimal for goal-directed behaviour and external responsiveness. Overall, this comparative analysis indicates that there are currently limitations to the use of these measures as tools to evaluate consciousness as a multidimensional phenomenon and that the relationship between these neural signatures and phenomenology requires closer scrutiny.

中文翻译：

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意识作为一种多维现象：对评估意识障碍的影响。

意识障碍（DoC）带来了重大的临床和伦理挑战，因为它们允许患者产生复杂形式的意识体验，而患者的有意行为和沟通受到高度限制或不存在。迫切需要基于大脑的评估能够精确、准确地表征个体 DoC 患者的意识状态。人们一直在努力开发意识的神经测量方法。然而，这些措施的验证具有挑战性，不仅因为我们缺乏关于许多 DoC 患者意识的基本事实，而且因为存在关于意识的开放本体论问题。有一种日益增长的、得到充分支持的观点认为，意识是一种多维现象，无法用分层的、容易排序的意识层次的理论结构来充分描述。意识的多维观点挑战了 DoC 评估背景下基于水平的神经测量的实用性。为了研究这些措施如何将意识映射为多维现象，本文将调查一系列研究，这些研究已在 DoC 以外的州应用，并且对意识体验有更多了解。这一比较证据表明，意识水平的测量对意识的某些维度比其他维度更敏感，并且不能假设提供意识状态的直接层次特征。例如，大脑复杂性水平的升高与以高度的感官丰富性和最小的注意力限制为特征的意识状态相关，但对于目标导向的行为和外部反应能力来说并不是最佳的。总体而言，这种比较分析表明，目前使用这些测量作为评估意识作为多维现象的工具存在局限性，并且这些神经特征和现象学之间的关系需要更仔细的审查。