Coma Science Group, GIGA-Consciousness, University of Liège, Liège, Belgium, Avenue de l'hôpital, 11, 4000 Liège, Belgium; Centre du Cerveau², University Hospital of Liège, Liège, Belgium, Avenue de l'Hôpital, 11, 4000 Liège, Belgium.
Coma Science Group, GIGA-Consciousness, University of Liège, Liège, Belgium, Avenue de l'hôpital, 11, 4000 Liège, Belgium; Department of Surgical, Medical, Molecular Pathology and Critical Care Medicine, University of Pisa, Pisa, Italy. Via Paradisa 2, 56124 Pisa, Italy.
Neuroimage. 2024 Sep;298:120759. doi: 10.1016/j.neuroimage.2024.120759. Epub 2024 Jul 26.
During fainting, disconnected consciousness may emerge in the form of dream-like experiences. Characterized by extra-ordinary and mystical features, these subjective experiences have been associated to near-death-like experiences (NDEs-like). We here aim to assess brain activity during syncope-induced disconnected consciousness by means of high-density EEG monitoring. Transient loss of consciousness and unresponsiveness were induced in 27 healthy volunteers through hyperventilation, orthostasis, and Valsalva maneuvers. Upon awakening, subjects were asked to report memories, if any. The Greyson NDE scale was used to evaluate the potential phenomenological content experienced during the syncope-induced periods of unresponsiveness. EEG source reconstruction assessed cortical activations during fainting, which were regressed out with subjective reports collected upon recovery of normal consciousness. We also conducted functional connectivity, graph-theoretic and complexity analyses. High quality high-density EEG data were obtained in 22 volunteers during syncope and unresponsiveness (lasting 22±8 s). NDE-like features (Greyson NDE scale total score ≥7/32) were apparent for eight volunteers and characterized by higher activity in delta, theta and beta2 bands in temporal and frontal regions. The richness of the NDE-like content was associated with delta, theta and beta2 bands cortical current densities, in temporal, parietal and frontal lobes, including insula, right temporoparietal junction, and cingulate cortex. Our analyses also revealed a higher complexity and that networks related to delta, theta, and beta2 bands were characterized by a higher overall connectivity paralleled by a higher segregation (i.e., local efficiency) and a higher integration (i.e., global efficiency) for the NDE-like group compared to the non-NDE-like group. Fainting-induced NDE-like episodes seem to be sustained by surges of neural activity representing promising markers of disconnected consciousness.
在昏厥期间，可能会以梦境般的体验形式出现与意识断开的状态。这些主观体验具有非凡和神秘的特征，与濒死样体验（类似 NDE）有关。我们旨在通过高密度 EEG 监测评估晕厥引起的与意识断开相关的脑活动。通过过度通气、直立和瓦尔萨尔瓦动作，在 27 名健康志愿者中诱发短暂的意识丧失和无反应。在苏醒后，要求受试者报告是否有记忆。使用 Greyson NDE 量表评估在晕厥引起的无反应期间经历的潜在现象学内容。使用 EEG 源重建评估昏厥期间的皮质激活，并用在恢复正常意识时收集的主观报告进行回归。我们还进行了功能连接、图论和复杂性分析。在 22 名志愿者的晕厥和无反应期间（持续 22±8 秒）获得了高质量的高密度 EEG 数据。有 8 名志愿者表现出类似 NDE 的特征（Greyson NDE 量表总分≥7/32），其特点是颞区和额区的 delta、theta 和 beta2 频段的活动较高。类似 NDE 的内容的丰富度与颞叶、顶叶和额叶，包括岛叶、右侧颞顶交界处和扣带皮质的 delta、theta 和 beta2 频段皮质电流密度有关。我们的分析还表明，类似 NDE 的组的复杂性更高，与 delta、theta 和 beta2 频段相关的网络的整体连通性更高，同时伴有更高的分离（即局部效率）和更高的集成（即全局效率）。晕厥引起的类似 NDE 发作似乎是由神经活动的激增维持的，这是与意识断开相关的有前途的标志物。
