On September 1st, 1953, William Scoville used a hand crank and a cheap drill saw to bore into a young man's skull, cutting away vital pieces of his brain and sucking them out through a metal tube. But this wasn't a scene from a horror film or a gruesome police report. Dr. Scoville was one of the most renowned neurosurgeons of his time, and the young man was Henry Molaison, the famous patient known as "H.M.", whose case provided amazing insights into how our brains work. As a boy, Henry had cracked his skull in an accident and soon began having seizures, blacking out and losing control of bodily functions. After enduring years of frequent episodes, and even dropping out of high school, the desperate young man had turned to Dr. Scoville, a daredevil known for risky surgeries. Partial lobotomies had been used for decades to treat mental patients based on the notion that mental functions were strictly localized to corresponding brain areas. Having successfully used them to reduce seizures in psychotics, Scoville decided to remove H.M.'s hippocampus, a part of the limbic system that was associated with emotion but whose function was unknown. At first glance, the operation had succeeded. H.M.'s seizures virtually disappeared, with no change in personality, and his IQ even improved. But there was one problem: His memory was shot. Besides losing most of his memories from the previous decade, H.M. was unable to form new ones, forgetting what day it was, repeating comments, and even eating multiple meals in a row. When Scoville informed another expert, Wilder Penfield, of the results, he sent a Ph.D student named Brenda Milner to study H.M. at his parents' home, where he now spent his days doing odd chores, and watching classic movies for the first time, over and over. What she discovered through a series of tests and interviews didn't just contribute greatly to the study of memory. It redefined what memory even meant. One of Milner's findings shed light on the obvious fact that although H.M. couldn't form new memories, he still retained information long enough from moment to moment to finish a sentence or find the bathroom. When Milner gave him a random number, he managed to remember it for fifteen minutes by repeating it to himself constantly. But only five minutes later, he forgot the test had even taken place. Neuroscientists had though of memory as monolithic, all of it essentially the same and stored throughout the brain. Milner's results were not only the first clue for the now familiar distinction between short-term and long-term memory, but show that each uses different brain regions. We now know that memory formation involves several steps. After immediate sensory data is temporarily transcribed by neurons in the cortex, it travels to the hippocampus, where special proteins work to strengthen the cortical synaptic connections. If the experience was strong enough, or we recall it periodically in the first few days, the hippocampus then transfers the memory back to the cortex for permanent storage. H.M.'s mind could form the initial impressions, but without a hippocampus to perform this memory consolidation, they eroded, like messages scrawled in sand. But this was not the only memory distinction Milner found. In a now famous experiment, she asked H.M. to trace a third star in the narrow space between the outlines of two concentric ones while he could only see his paper and pencil through a mirror. Like anyone else performing such an awkward task for the first time, he did horribly. But surprisingly, he improved over repeated trials, even though he had no memory of previous attempts. His unconscious motor centers remembered what the conscious mind had forgotten. What Milner had discovered was that the declarative memory of names, dates and facts is different from the procedural memory of riding a bicycle or signing your name. And we now know that procedural memory relies more on the basal ganglia and cerebellum, structures that were intact in H.M.'s brain. This distinction between "knowing that" and "knowing how" has underpinned all memory research since. H.M. died at the age of 82 after a mostly peaceful life in a nursing home. Over the years, he had been examined by more than 100 neuroscientists, making his the most studied mind in history. Upon his death, his brain was preserved and scanned before being cut into over 2000 individual slices and photographed to form a digital map down to the level of individual neurons, all in a live broadcast watched by 400,000 people. Though H.M. spent most of his life forgetting things, he and his contributions to our understanding of memory will be remembered for generations to come.
在 1953 年,9 月 1 日 威廉·斯科维尔使用 一个起动手柄和一个廉价电钻 在一个年轻男子的头骨上钻孔 切除了他脑部的重要部分 并且用金属管子把它们吸走 但是这并不是恐怖电影场景 或者一个可怕的警察报告 斯科维尔医生是那时候最有名 的神经外科医生之一 这位年轻男子是亨利·莫莱森 被熟知为「H.M.」的有名病人 他的病例为我们了解大脑如何运作 提供了神奇的认识 儿时,亨利在一次意外中 撞裂了他的头骨 很快他开始癫痫发作,昏迷 和丧失控制身体的能力 在常年出现这种经常偶发性发作, 甚至高中退学后 这个绝望的年轻人找到了 斯科维尔医生 一个因冒险手术而闻名的敢干的人 部分前脑叶白质切除术 常年用于治疗精神患者 理论基础是大脑功能是严格局部化 于相应大脑区域的 曾成功使用它们减少精神病患者发作 斯科维尔决定移除 H.M. 的海马组织 它是人脑边缘系统的一部分 与情感相关 但是具体功能仍然不清楚 刚开始,手术成功了 H.M.的发作几乎消失了 和个人性格没有改变 而且他的智力甚至提高了 但是很快出现了一个问题: 他的记忆被打乱了 除了失去他早年的大部分记忆 H.M. 不能形成新的记忆 他会忘记日期 重复说话,甚至连续吃很多顿饭 当斯科维尔通知其他专家 结果,韦尔德·潘菲尔德 派了他的博士学生布伦达·米尔纳 在亨利父母家研究 H.M. 的情况 H.M. 现在整天做奇怪的事 重复看经典电影 她发现通过一系列的测试和访谈 不仅对记忆研究产生巨大贡献 它重新定义了记忆的内涵 米尔纳的其中一个发现 透露了明显的事实 虽然 H.M. 不能够形成新的记忆, 他仍然保留信息 足够长时间来完成一个句子 或者找到浴室 当米尔纳给他一个随机数字 他使用15分钟记住它 通过经常重复这个数字 但是仅仅五分钟后, 他忘记这个测试曾经发生过 神经科学家曾想过记忆是整体的 所有记忆大体一样 而且保存在整个大脑中 米尔纳的结果并不是第一个 得出现在相似的 关于长期记忆和短期记忆区别的线索 但是展示了每个记忆使用大脑不同区域 我们现在知道记忆的形成涉及很多步骤 在瞬间感受数据在大脑皮层 被神经元短暂转录 它传递到海马组织 在那里通过特殊蛋白质加工来加强 皮质突触连接 如果经历足够强烈 或者我们间歇性地 在前几天经常回忆 海马组织会把记忆传递回去大脑皮层 形成永久存储 H.M. 的大脑可以形成首要的印象 但是没有海马组织进行记忆巩固 他们逐渐毁坏 就像信息乱写在沙上 但是这并不是米尔纳发现的唯一记忆分区 在一个当今闻名的实验中 她要求H.M.在两个星星的线条空隔间 临摹出第三个星星 但他只可以通过镜子看到他的纸和笔 像其他所有第一次进行 这个尴尬任务的人一样 他做得很糟糕 但惊讶的是,他在重复尝试后进步了 甚至虽然他并没有之前尝试的记忆 他的无意识运动中心记忆了 意识大脑忘记的信息 米尔纳发现关于名字、日期 和事实的陈述性记忆 和关于骑自行车或者签自己名字的 程序性记忆不同 而且我们现在知道程序性记忆 依赖更多基底神经节和小脑 这些结构仍然保留在H.M.的大脑中 「懂得那样」和「懂得怎样」的区别 从此成为了所有记忆研究的基础 H.M.在82岁时安详地卒于疗养院 这些年来,他被多于100位 神经科学家研究 使他的大脑成为历史上 最多人研究的大脑 当他死亡的时候,他的 大脑被保存和扫描 然后被切成多于2000块 独立的切片 并且被照相来生成一个细致到 神经元个体级别的电子图 过程全部现场直播并且有40万群众观看 尽管H.M.花费大半生在忘事 但他和他对人类了解记忆的贡献 会被每一代人永记