麻醉药帮助我们理解什么是意识

That's because, while you need a brain to have consciousness, you might not need a brain to experience pain. In the 1990s, scientists ran tests on rats and goats, studying how the effects of anesthetics changed as different parts of the brain were intentionally damaged or removed. The amount of the drugs necessary to prevent the animals from moving in response to pain didn't change as the cortex, the thalamus and the brain stem were destroyed. "Turns out, they were measuring a spinal-cord reflex, which is a much more primitive thing and has nothing to do with consciousness," Hameroff said. Outward signs of consciousness may or not may not have anything to do with actual awareness.
这是因为，虽然保持意识需要大脑，但感受痛苦却未必需要大脑的参与。20世纪90年代，科学家们在大鼠和山羊身上进行试验，他们故意损伤或去除了不同的大脑部位，然后研究麻醉剂的作用发生了怎样的改变。当皮层、丘脑和脑干受损后，要防止动物因疼痛而挣扎所需的药物剂量并没有发生改变。“事实证明，他们之前检测的只是脊髓反射，这是一种非常原始的反应，跟意识没有任何关系，”哈姆鲁夫说。意识的外在表现与真正的觉醒状态之间可能存在关联，也可能完全是两码事。

In everyday life, it's nearly impossible to ever know whether someone is conscious or not, Hameroff said, even if it seems glaringly obvious. Philosophers are fond of pointing out that, for all you know, you're surrounded by people who appear to be fully conscious but who experience none of it subjectively. (They frequently trot out these beings for thought experiments and call them "philosophical zombies.") But for those under anesthesia and the knife, such sophistry offers little solace.
在日常生活中，想要确知某个人的意识状态几乎是不可能的，哈姆鲁夫说，尽管它似乎是如此显而易见。哲学家们很喜欢这样讲：你只知道你周围的人看起来都具有完整的意识，但没有一个人对此有任何主观体验。（他们经常在这些人面前炫耀所谓的“思想实验”，并称他们为“哲学僵尸”。）只是对于那些身在麻醉和手术刀下的患者而言，这样的诡辩起不到什么宽慰效果。

Increasingly, research on what happens to the brain under anesthesia suggests that the synthesis and integration of information among many different parts of the brain is the best measure of consciousness. Some people, Mashour said, go so far as to say that this communication among regions is consciousness itself. Our subjective experience of the world might arise as a byproduct of the brain's piecing together different sensory inputs.
有越来越多关于麻醉状态下大脑功能的研究表明，对来自大脑多个不同部位的信息加以综合的能力是衡量意识的最佳指标。马舒尔指出，有些人甚至认为这种不同脑区之间的通讯交流就是意识本身。我们对世界的主观体验很可能是大脑试图拼凑不同的感觉输入信息时产生的副产物。

It's easy to see the connections between this idea and the "ping" study. When the brain falls asleep, drifts into a coma or comes under the influence of anesthetic drugs, the ability to synthesize information disappears, though the brain doesn't cease to function. Figuring out a method for measuring intrabrain communication will be crucial for preventing operating-table awareness.
很容易看出，上述观点与脑电脉冲研究之间存在一定关联。当大脑陷入熟睡、昏迷或麻醉药物的影响之下时，虽然它并没有停止运作，但其综合信息的能力却消失了。找出一种可测定脑内通讯的方法对于防止患者在手术台上醒觉至关重要。

In the June 2013 issue of the journal Anesthesiology, Mashour proposed just that: a monitor that focuses on the brain's ability to communicate within itself. It's similar to the "ping" study but tracks a different signal. Activity in conscious brains has been shown to loop between sensory areas (the visual cortex in the rear of the brain, for example) and the higher-level parts of the brain associated with processing information (like the temporal lobe, just behind your ears). Mashour and others call this "recurrent processing": Signals travel from the sensory areas to the processing areas and back again. When somebody is unconscious, the recurrent proc-essing disappears. Mashour's study showed that this pattern — or lack thereof — is present in the brains of people anesthetized with three different classes of drugs. It's not just a side effect of one kind of medication. His work suggests that anesthesia monitors might be more effective if, rather than measuring the presence of electrical waves produced bythe brain, they monitor how electrical signals move around the brain.
在2013年6月的《麻醉学》(Anesthesiology)杂志上，马舒尔建议：使用一台监测仪来专门监测大脑内部的通讯能力。这与脑电脉冲研究有点类似，但它们跟踪的是不同的信号。研究显示，在意识清醒的大脑中，感觉区（例如，大脑后部的视觉皮层）与信息加工相关的高级区域（比如位于耳后侧的颞叶）之间存在脑部活动环路。马舒尔等称其为“回返加工”：信号从感觉区进入加工区，然后再返回感觉区。在人失去意识后，这种“回返加工”也随之烟消云散。马舒尔的研究表明，在三种不同类别药物的麻醉下，人的大脑中都呈现了这种模式的存在和缺失。这并不是某一种药物的副作用。这项工作表明，如果麻醉监测器能够监测电信号如何在大脑之中传送，可能会比单纯测定大脑是否产生电波更为有效。

Should such a device be developed, it would be good news not only for those 0.13 percent of patients but also for fans of Enlightenment philosophy. Mashour told me that the synthetic model of consciousness dates back to Immanuel Kant — his "Critique of Pure Reason" might be vindicated by neuroscience. "Kant said there has to be some process that takes individual processing and connects it together into a unified experience," Mashour said. "Over the years, we've teased out the parts of the brain necessary for appreciating vision, color, motion. They're all mediated by different brain areas. But how does the brain put all that together into single perception?" For Kant, this was clear long before EEG monitors and anesthetics. "Without this synthesis," he wrote in 1781, "the manifold would not be united in one consciousness."
如果能够开发这样的设备，对于那0.13%的不幸患者以及启蒙哲学的粉丝们都是大好消息。马舒尔告诉我，意识的综合模式最早可以追溯到伊曼纽尔·康德(Immanuel Kant)——他的《纯粹理性批判》(Critique of Pure Reason)或可因神经科学的发展而获得平反。“康德认为，必有一定的过程将单独的信息整理加工，使其彼此联系并结合为一体，即成为经验，”马舒尔说。“多年来，我们已经逐步确定景象、色彩和运动的评鉴由大脑的不同区域所介导。然而，大脑是如何将它们整合为统一的感知印象的？”康德所处的时代远在脑电监测仪及麻醉剂的发明和使用之前，1781年，他写道，很明显，“如果没有这种综合作用，多姿多彩而散乱的感觉信息将不可能在一个意识中实现统一。”