Wong Kin Foon Kevin, Smith Anne C, Pierce Eric T, Harrell P Grace, Walsh John L, Salazar-Gómez Andrés Felipe, Tavares Casie L, Purdon Patrick L, Brown Emery N
Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, MA, USA; Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, USA.
Department of Bioengineering, University of Illinois at Chicago, Chicago, IL, USA.
J Neurosci Methods. 2014 Apr 30;227:65-74. doi: 10.1016/j.jneumeth.2014.01.026. Epub 2014 Feb 14.
Accurate quantitative analysis of the changes in responses to external stimuli is crucial for characterizing the timing of loss and recovery of consciousness induced by anesthetic drugs. We studied induction and emergence from unconsciousness achieved by administering a computer-controlled infusion of propofol to ten human volunteers. We evaluated loss and recovery of consciousness by having subjects execute every 4s two interleaved computer delivered behavioral tasks: responding to verbal stimuli (neutral words or the subject's name), or less salient stimuli of auditory clicks.
We analyzed the data using state-space methods. For each stimulus type the observation model is a two-stage binomial model and the state model is two dimensional random walk in which one cognitive state governs the probability of responding and the second governs the probability of correctly responding given a response. We fit the model to the experimental data using Bayesian Monte Carlo methods.
During induction subjects lost responsiveness to less salient clicks before losing responsiveness to the more salient verbal stimuli. During emergence subjects regained responsiveness to the more salient verbal stimuli before regaining responsiveness to the less salient clicks.
COMPARISON WITH EXISTING METHOD(S): The current state-space model is an extension of previous model used to analyze learning and behavioral performance. In this study, the probability of responding on each trial is obtained separately from the probability of behavioral performance.
Our analysis provides a principled quantitative approach for defining loss and recovery of consciousness in experimental studies of general anesthesia.
准确地定量分析对外部刺激反应的变化，对于确定麻醉药物诱导意识丧失和恢复的时间至关重要。我们对10名人类志愿者进行了研究，通过计算机控制输注丙泊酚来诱导意识丧失和苏醒。我们通过让受试者每4秒执行两项交错的计算机提供的行为任务来评估意识的丧失和恢复：对言语刺激（中性词或受试者的名字）做出反应，或对不太突出的听觉咔哒声刺激做出反应。
我们使用状态空间方法分析数据。对于每种刺激类型，观测模型是一个两阶段二项式模型，状态模型是二维随机游走，其中一种认知状态控制反应的概率，另一种认知状态控制给定反应时正确反应的概率。我们使用贝叶斯蒙特卡罗方法将模型拟合到实验数据。
在诱导过程中，受试者在对更突出的言语刺激失去反应之前，先对不太突出的咔哒声失去反应。在苏醒过程中，受试者在对不太突出的咔哒声恢复反应之前，先对更突出的言语刺激恢复反应。
当前的状态空间模型是先前用于分析学习和行为表现的模型的扩展。在本研究中，每次试验的反应概率与行为表现的概率是分别获得的。
我们的分析为全身麻醉实验研究中定义意识的丧失和恢复提供了一种有原则的定量方法。
