Propofol is a short-acting medication that results in decreased levels of consciousness and is used for general anesthesia. Although it is the most commonly used anesthetic in the world, much remains unknown about the mechanisms by which it induces a loss of consciousness. Characterizing anesthesia-induced alterations to brain network activity might provide a powerful framework for understanding the neural mechanisms of unconsciousness. The aim of this work was to model brain activity in healthy brains during various stages of consciousness, as induced by propofol, in the auditory paradigm. We used the generalized Ising model (GIM) to fit the empirical fMRI data of healthy subjects while they listened to an audio clip from a movie. The external stimulus (audio clip) is believed to be at least partially driving a synchronization process of the brain activity and provides a similar conscious experience in different subjects. In order to observe the common synchronization among the subjects, a novel technique called the inter subject correlation (ISC) was implemented. We showed that the GIM-modified to incorporate the naturalistic external field-was able to fit the empirical task fMRI data in the awake state, in mild sedation, in deep sedation, and in recovery, at a temperature T* which is well above the critical temperature. To our knowledge this is the first study that captures human brain activity in response to real-life external stimuli at different levels of conscious awareness using mathematical modeling. This study might be helpful in future to assess the level of consciousness of patients with disorders of consciousness and help in regaining their consciousness.

中文翻译：

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使用广义 Ising 模型模拟意识改变状态下的听觉刺激大脑

丙泊酚是一种短效药物，可导致意识水平下降，用于全身麻醉。尽管它是世界上最常用的麻醉剂，但对其引起意识丧失的机制仍有很多未知。表征麻醉引起的大脑网络活动的改变可能为理解无意识的神经机制提供一个强有力的框架。这项工作的目的是在听觉范式中模拟由丙泊酚引起的不同意识阶段的健康大脑的大脑活动。我们使用广义 Ising 模型 (GIM) 来拟合健康受试者在听电影音频剪辑时的经验 fMRI 数据。外部刺激（音频剪辑）被认为至少部分地驱动了大脑活动的同步过程，并在不同的受试者中提供了类似的意识体验。为了观察主体之间的共同同步，实施了一种称为主体间相关性（ISC）的新技术。我们展示了 GIM 修改以纳入自然外场 - 能够适应清醒状态、轻度镇静、深度镇静和恢复中的经验任务 fMRI 数据，温度 T* 远高于临界温度。据我们所知，这是第一项使用数学模型捕捉人类大脑活动以响应不同意识意识水平的现实生活外部刺激的研究。