General anesthesia shuts off conscious¹ awareness, but what do our brains process while we’re under?
全身麻醉会阻断人的主观意识感知，但在麻醉失去意识期间，我们的大脑究竟在处理什么信息？
Individual neurons in a brain region known for its role in memory consolidation can detect² unexpected sounds, decode the nuances of language and even predict³ upcoming word types in a sentence, all while a patient is fully anesthetized, researchers report May 6 in Nature.
研究人员于5月6日在《自然》杂志发表研究：大脑中负责记忆巩固的脑区里，单个神经元即便在患者被完全麻醉时，依然可以察觉意外声响、辨析语言中的细微语义，甚至预判一句话后续将要出现的词汇类别。
Scientists have been gathering mounting⁴ evidence that even when unconscious, our brains can track certain aspects of speech. “The field was already moving toward a more nuanced⁵ picture [of what the unconscious brain can do], but this study pushes the boundary considerably further,” says Athena Akrami, a neuroscientist at University College London who was not involved with the research.
越来越多的证据显示，人类在无意识状态下，大脑依旧能捕捉语言的部分信息。伦敦大学学院神经科学家雅典娜・阿克拉米并未参与本次研究，她表示：“业内本就对无意识大脑的能力有了更细化的认知，而这项研究极大地拓宽了现有研究边界。”
To peer into the unconscious brain, neurosurgeon Kalman Katlowitz of Baylor College of Medicine in Houston and colleagues monitored⁶ activity in the hippocampi of seven anesthetized patients. The team used a technology developed within the last few years called a Neuropixels probe. These high-density microelectrodes can record the electrical activity of hundreds of individual neurons simultaneously⁷, rather than listening to the collective⁸ activity of groups of neurons. The team inserted these probes into patients’ hippocampi, in tissue slated for surgical removal as part of epilepsy treatment.
为探究无意识状态下的大脑运作，美国休斯顿贝勒医学院神经外科医生卡尔曼・卡特洛维茨及其团队监测了七名麻醉患者海马体的神经活动。课题组使用了近年新问世的神经像素探针技术：这类高密度微电极能够同步记录数百个独立神经元的电信号，而非仅采集一簇神经元的整体活动数据。研究人员将探针植入患者海马组织，该部分脑组织原本就因癫痫治疗方案需要手术切除。
While the patients were under general anesthesia, the researchers played various sounds through headphones. For some patients, this consisted of a series of uniform pure tones interspersed with occasional, unexpected “oddball” tones of a different frequency. For others, the researchers played 10 to 20 minutes of educational videos and storytelling podcasts, like The Moth Radio Hour, to evaluate⁹ how the brain processes natural speech.
患者全麻期间，研究人员通过耳机播放各类音频。一部分受试者收听一连串音调统一的纯音，音频中随机穿插频率不同、突兀的异常音调；另一部分受试者收听10至20分钟科普视频原声与故事类播客（如《飞蛾电台》），以此测评大脑处理自然口语的规律。
