Are Memories Transferable? Meet the Scientists Replicating an Infamous Study to Find Out

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Are Memories Transferable? Meet the Scientists Replicating an Infamous Study to Find Out

Save this story. The original version of this story appeared in Quanta Magazine. It was the dead of winter in Boston. The surface of the Charles River was frozen solid. But Zachary Kelso braved the biting cold to finally put to rest a mystery that has haunted neuroscience labs for over half a century.

保存这篇报道。本文最初发表于《量子杂志》。当时波士顿正值隆冬，查尔斯河面结了厚厚的冰。但扎卡里·凯尔索（Zachary Kelso）冒着刺骨的严寒，试图彻底解开一个困扰神经科学实验室半个多世纪的谜团。

To do that, Kelso, a research assistant in the Harvard lab of the neuroscientist Sam Gershman, needed some worms. Specifically, planarians: arrow-headed flatworms, which are among the simplest creatures to possess a brain and a nervous system with bilateral symmetry like ours. Normally, labs order these widely used model organisms from biological supply companies. But the mail-order worms weren’t up to snuff. So Gershman had dispatched Kelso to the Charles’ icy banks to catch some wild ones. “I thought, ‘I’m going to look crazy because I’m using a hammer to beat through the ice,’” Kelso recalled. “So I wore the more business end of business casual.”

为了做到这一点，身为神经科学家萨姆·格什曼（Sam Gershman）哈佛实验室研究助理的凯尔索需要一些蠕虫。具体来说是涡虫：一种箭头状的扁形虫，它们是拥有大脑和像我们一样具有双侧对称神经系统的最简单生物之一。通常，实验室会从生物供应公司订购这些广泛使用的模式生物。但邮购的蠕虫质量不达标，于是格什曼派凯尔索去查尔斯河冰冷的岸边捕捉野生涡虫。“我当时想，‘我用锤子砸冰的样子一定看起来很疯，’”凯尔索回忆道，“所以我特意穿得比较商务休闲，显得正式一点。”

It wouldn’t be the last time Kelso found himself in this situation. The Charles River planarians, it turned out, didn’t cut it either. Neither did the worms he sourced while stream-hopping around Eugene, Oregon, in March 2025. Nor did the ones he fished from Michigan lakes that June—this time in thigh-high waders—while picnicking families gawked from shore. Kelso diligently turned over rocks, angled with bits of meat tied to a string, and even followed maps from a vintage guidebook called The Fresh-Water Triclads of Michigan. But his adventure was fruitless. Sure, he caught plenty of planarians. But back in Gershman’s lab, none of them would do what they were supposed to do.

这并不是凯尔索最后一次陷入这种境地。事实证明，查尔斯河的涡虫也不行。他在2025年3月于俄勒冈州尤金市周边溪流中采集的蠕虫也不行。同年6月，他穿着齐大腿高的涉水裤从密歇根州的湖泊中捕捞的蠕虫也不行，当时岸边野餐的家庭还对他投来了诧异的目光。凯尔索勤奋地翻动石头，用系着肉块的绳子垂钓，甚至还参考了一本名为《密歇根淡水三肠目涡虫》的古旧指南地图。但他的冒险毫无收获。当然，他确实抓到了很多涡虫，但回到格什曼的实验室后，它们没有一个能表现出预期的行为。

In the 1960s, an eccentric behavioral psychologist named James McConnell convinced the scientific establishment that planarian worms, like Pavlov’s dogs, could be classically conditioned—and that memories of this training could be transferred from worm to worm through cannibalism. These bizarre findings were replicated by other scientists, and worm training became a staple of high school science fairs. Now, 60 years later, the worms have stopped learning, and nobody knows why.

20世纪60年代，一位名叫詹姆斯·麦康奈尔（James McConnell）的古怪行为心理学家让科学界相信，涡虫像巴甫洛夫的狗一样可以进行经典条件反射训练，而且这种训练的记忆可以通过同类相食在蠕虫之间传递。这些离奇的发现被其他科学家复制，训练蠕虫甚至成了高中科学博览会的常客。如今，60年过去了，这些蠕虫却不再学习了，没人知道原因。

I first learned about this scientific mystery while reporting another piece about what a cell can remember. As I dug into the historical literature on memory research, I kept coming across McConnell’s strange worm experiments, which captivated a generation of scientists before disappearing entirely. Planarian memory had itself been forgotten. I was content to dismiss it as a fluke of history until Gershman mentioned, in passing during an interview, that in addition to their work with the unicellular ciliate Stentor coeruleus, his lab was attempting to reproduce some wacky worm experiments from the 1960s. Had I heard of them?

我最初是在报道另一篇关于细胞记忆的文章时了解到这个科学谜团的。当我深入研究记忆研究的历史文献时，不断看到麦康奈尔那些奇怪的蠕虫实验，它们曾让一代科学家着迷，随后却彻底销声匿迹。涡虫记忆本身也已被遗忘。我本打算将其视为历史的偶然，直到格什曼在一次采访中顺口提到，除了对单细胞纤毛虫——蓝喇叭虫（Stentor coeruleus）的研究外，他的实验室还试图重现20世纪60年代的一些古怪蠕虫实验。我听说过吗？

Planarian worms have remarkable regenerative capacity. A fragment that’s 1/279 of the original worm can regrow into a normal adult in weeks. Photograph: Ernest Cooper. Gershman, I learned, was keen to pick up where McConnell had left off. As part of a growing cohort of cognitive scientists looking beyond the brain for clues to the origins and basis of memory, he’s fascinated by any creature that seems to remember without the benefit of neural, synaptic networks. Little Stentor coeruleus, for example, can modify its behavior based on previous experience—quite a feat for a single-celled creature that can’t possibly have a neuron. Planarian worms, if McConnell’s findings were to be believed, might be the next great model organism for memory research.

涡虫具有惊人的再生能力。原虫1/279大小的碎片能在几周内长成正常的成体。摄影：欧内斯特·库珀（Ernest Cooper）。我了解到，格什曼热衷于从麦康奈尔中断的地方继续研究。作为日益壮大的认知科学家群体的一员，他正在大脑之外寻找记忆起源和基础的线索，并对任何似乎能在没有神经和突触网络的情况下进行记忆的生物着迷。例如，小小的蓝喇叭虫可以根据以往的经验改变其行为——对于一个不可能拥有神经元的单细胞生物来说，这相当了不起。如果麦康奈尔的发现可信，涡虫可能会成为下一个伟大的记忆研究模式生物。

The trouble was, it wasn’t going well. In fact, no matter how hard Gershman tried to train them, none of his planarians would learn a thing.

问题在于，进展并不顺利。事实上，无论格什曼如何努力训练，他的涡虫什么也学不会。

Can a worm learn? When McConnell posed the question in the early 1950s, the notion that memory had something to do with synaptic associations between neurons in the brain was just beginning to gain currency. McConnell, then a graduate student in psychology at the University of Texas, reasoned that planarians—among the simplest creatures with true neurons—should therefore be able to learn.

蠕虫能学习吗？当麦康奈尔在20世纪50年代初提出这个问题时，关于记忆与大脑神经元之间突触关联有关的观点才刚刚开始流行。当时还是德克萨斯大学心理学研究生的麦康奈尔推断，涡虫作为拥有真正神经元的最简单生物之一，理应具备学习能力。

His early worm experiments were not particularly novel. He simply substituted worms for rats in what were, at the time, standard classical conditioning studies: repeatedly shocking the worms while exposing them to a bright light. After a period of this training, the worms came to associate the light with the shock and scrunched their bodies in anticipation whenever the light flashed. Voilà: worm learning!

他早期的蠕虫实验并没有什么特别新颖之处。他只是在当时标准的经典条件反射研究中用蠕虫代替了老鼠：在用强光照射蠕虫的同时反复电击它们。经过一段时间的训练，蠕虫开始将光线与电击联系起来，每当光线闪烁时，它们就会因预期电击而蜷缩身体。瞧：蠕虫学会了！

Planarians have stranger features to offer for experiments. If a planarian is chopped in half, both halves will regrow into a new worm—the tail will grow a new head, and the head will grow a new tail. A fragment as small as 1/279 of the original worm can regrow into a completely normal adult worm in a matter of weeks, a regenerative capacity so powerful that, as one early naturalist put it, planarians are effectively “immortal under the edge of the knife.” For McConnell, this ability begged the question: When you chop a worm in half, do both halves remember?

涡虫还有更奇怪的实验特性。如果将一只涡虫切成两半，两半都会再生长成一只新的蠕虫——尾部会长出一个新头，头部会长出一条新尾巴。小至原虫1/279的碎片能在几周内长成一只完全正常的成年涡虫，这种再生能力非常强大，正如一位早期博物学家所言，涡虫实际上是“刀刃下的不朽者”。对麦康奈尔来说，这种能力引出了一个问题：当你把一只蠕虫切成两半时，两半都有记忆吗？

This is where the real worm torture began. In the ’60s, McConnell, by then a young professor at the University of Michigan, started beheading his trained planarians. The worms that grew back from the severed heads behaved as the originals had, associating the light with the shock—a result he expected, given the preservation of their primitive brains. What surprised McConnell was that the worms that regenerated from headless tails remembered, too. This meant that whatever form the worms’ memories took, they weren’t the exclusive purview of the brain. “It appeared that the memories were laid down throughout the animal’s body,” McConnell later reflected.

真正的蠕虫折磨从这里开始。在60年代，当时已是密歇根大学年轻教授的麦康奈尔开始将他训练过的涡虫斩首。从断头处长出的蠕虫表现得与原虫一样，将光线与电击联系起来——考虑到它们原始大脑的保留，这是他预料之中的结果。让麦康奈尔惊讶的是，从无头尾部再生出来的蠕虫也记得。这意味着无论蠕虫的记忆以何种形式存在，它们都不是大脑的专属领域。“记忆似乎存在于动物的整个身体中，”麦康奈尔后来反思道。

James McConnell stands next to a printed logo of The Worm Runner’s Digest, the half-satirical scientific journal he published from his lab at the University of Michigan. Photograph: University of Michigan News and Information Services. Thrilled, McConnell pushed his experiments further. He cut the worms into smaller and…

詹姆斯·麦康奈尔站在《蠕虫跑者文摘》（The Worm Runner’s Digest）的印刷标志旁，这是他在密歇根大学实验室出版的一份半讽刺性的科学期刊。摄影：密歇根大学新闻与信息服务部。麦康奈尔感到兴奋，他进一步推进了实验。他把蠕虫切得更小，并且……