Breakdown in cortical effective connectivity during midazolam-induced loss of consciousness
Breakdown in cortical effective connectivity during midazolam-induced loss of consciousness
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DOI：
10.1073/pnas.0913008107
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发表时间：
2010-02-09
影响因子：
11.1
通讯作者：
Pearce, Robert A.
中科院分区：
文献类型：
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作者：
Ferrarelli, Fabio;Massimini, Marcello;Pearce, Robert A.
通过采用经颅磁刺激（TMS）与高密度脑电图（EEG）相结合，我们最近报道，在早期非快速眼动（NREM）睡眠期间，皮层有效连接被破坏。这是一个时间，当受试者，如果被唤醒，可能会报告很少或没有意识内容。我们假设，类似的皮质有效连接的崩溃可能是药物引起的意识丧失（意识丧失）的基础。在这里，我们测试了这一假设，通过比较脑电图反应TMS清醒和清醒引起的苯二氮卓类咪达唑仑。与自发睡眠状态不同，受试者的警惕性水平可以在药物治疗期间反复监测。我们发现，与清醒期间不同，在清醒期间，TMS触发多个皮层区域的反应持续> 300 ms，在咪达唑仑诱导的睡眠期间，TMS诱发的活动是局部的，持续时间较短。此外，诱发皮层电流传播的测量（显著电流散射，SCS）可以可靠地区分意识和意识障碍。这些结果与早期NREM睡眠中观察到的结果相似，并表明皮质有效连接性的破坏可能是以LOC为特征的疾病的共同特征。此外，这些结果表明，它可能是可能的，使用TMS-EEG评估意识在麻醉和病理条件下，如昏迷，植物人状态，和最低意识状态。
By employing transcranial magnetic stimulation (TMS) in combination with high-density electroencephalography (EEG), we recently reported that cortical effective connectivity is disrupted during early non-rapid eye movement (NREM) sleep. This is a time when subjects, if awakened, may report little or no conscious content. We hypothesized that a similar breakdown of cortical effective connectivity may underlie loss of consciousness (LOC) induced by pharmacologic agents. Here, we tested this hypothesis by comparing EEG responses to TMS during wakefulness and LOC induced by the benzodiazepine midazolam. Unlike spontaneous sleep states, a subject's level of vigilance can be monitored repeatedly during pharmacological LOC. We found that, unlike during wakefulness, wherein TMS triggered responses in multiple cortical areas lasting for > 300 ms, during midazolam-induced LOC, TMS-evoked activity was local and of shorter duration. Furthermore, a measure of the propagation of evoked cortical currents (significant current scattering, SCS) could reliably discriminate between consciousness and LOC. These results resemble those observed in early NREM sleep and suggest that a breakdown of cortical effective connectivity may be a common feature of conditions characterized by LOC. Moreover, these results suggest that it might be possible to use TMS-EEG to assess consciousness during anesthesia and in pathological conditions, such as coma, vegetative state, and minimally conscious state.