Crone Julia S, Lutkenhoff Evan S, Vespa Paul M, Monti Martin M
Department of Psychology, University of California Los Angeles, Los Angeles, CA 90095, USA.
Department of Neurosurgery, University of California Los Angeles, Los Angeles, CA 90095, USA.
Neurosci Conscious. 2020 Jun 14;2020(1):niaa008. doi: 10.1093/nc/niaa008. eCollection 2020.
An increasing amount of studies suggest that brain dynamics measured with resting-state functional magnetic resonance imaging (fMRI) are related to the state of consciousness. However, the challenge of investigating neuronal correlates of consciousness is the confounding interference between (recovery of) consciousness and behavioral responsiveness. To address this issue, and validate the interpretation of prior work linking brain dynamics and consciousness, we performed a longitudinal fMRI study in patients recovering from coma. Patients were assessed twice, 6 months apart, and assigned to one of two groups. One group included patients who were unconscious at the first assessment but regained consciousness and improved behavioral responsiveness by the second assessment. The other group included patients who were already conscious and improved only behavioral responsiveness. While the two groups were matched in terms of the average increase in behavioral responsiveness, only one group experienced a categorical change in their state of consciousness allowing us to partially dissociate consciousness and behavioral responsiveness. We find the variance in network metrics to be systematically different across states of consciousness, both within and across groups. Specifically, at the first assessment, conscious patients exhibited significantly greater variance in network metrics than unconscious patients, a difference that disappeared once all patients had recovered consciousness. Furthermore, we find a significant increase in dynamics for patients who regained consciousness over time, but not for patients who only improved responsiveness. These findings suggest that changes in brain dynamics are indeed linked to the state of consciousness and not just to a general level of behavioral responsiveness.
越来越多的研究表明，通过静息态功能磁共振成像（fMRI）测量的脑动力学与意识状态有关。然而，研究意识的神经元相关性面临的挑战是意识（恢复）与行为反应性之间的混杂干扰。为了解决这个问题，并验证先前将脑动力学与意识联系起来的研究工作的解释，我们对从昏迷中恢复的患者进行了一项纵向fMRI研究。患者接受了两次评估，间隔6个月，并被分为两组。一组包括在第一次评估时无意识但在第二次评估时恢复意识并改善行为反应性的患者。另一组包括已经有意识且仅改善行为反应性的患者。虽然两组在行为反应性的平均增加方面相匹配，但只有一组经历了意识状态的绝对变化，这使我们能够部分区分意识和行为反应性。我们发现，无论是在组内还是组间，网络指标的方差在不同意识状态下存在系统性差异。具体而言，在第一次评估时，有意识的患者在网络指标上的方差显著大于无意识的患者，而一旦所有患者都恢复意识，这种差异就消失了。此外，我们发现恢复意识的患者随时间推移动力学有显著增加，但仅改善反应性的患者则没有。这些发现表明，脑动力学的变化确实与意识状态有关，而不仅仅与行为反应性的一般水平有关。
