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When you want to remember where you left your keys, you will, hopefully, conjure up a sort of image or idea of where you last had them.
你想记住把钥匙放在哪儿时，很可能会想起上次把钥匙放在那个地方的一个形象或想法。
While it may seem like that memory just magically appears in your mind's eye, the truth is that memories are far more physical.
虽然记忆似乎只是奇迹般地出现在脑海中，但事实是，记忆远比身体方面的印象丰富得多。
That means they have to live somewhere in your brain.
这意味着记忆生活在大脑的某个部位。
But, like, where? Is there a shelf labeled "keys" right next to the one that says "that time I tripped and fell down during the school play"?
但在哪里？有没有一个标有“钥匙”的架子，就挨着写有“那次我在学校玩耍时绊倒了”的书架？
Well it's definitely not that literal.
这绝对不是字面意思。
But thanks to advances in neuroscience, we can finally pinpoint the actual location of a memory; at least if you're a mouse.
但由于神经科学的进步，我们终于能精确定位记忆的实际位置；至少如果你是一只老鼠的话。
To find a memory, first you have to make one.
要找到记忆，必须先创造一个。
And it's easy to do that, you just do something.
这很容易做到，你只要做点事情。
Anything, just like, watch me do this! That's in your brain now! You're stuck with it!
任何事，比如看我做这个！现在它就在你脑子里了！你记住了它！
Your brain will then pick a bunch of cells to store a memory of the thing you just experienced, and it will activate them all at the same time.
大脑会挑选出一群细胞来存储你刚经历过事情的记忆，它也会同时激活它们。
But those cells aren't all in the same place, because the parts in your brain specialize in different things.
但这些细胞并不都在同一个地方，因为大脑中的部位专门处理不同的东西。
Your brain will pick cells across regions to store all the different aspects of a memory.
大脑会选择不同区域的细胞，来存储记忆的所有不同方面。
For example, neurons in the visual cortex will store what you were seeing, and the cells in your amygdala will store how you were feeling.
例如，视觉皮层的神经元会储存看到的事物，而杏仁核的细胞则会储存感受。
That specific pattern of cells, all firing together, is what the memory is now, in all of its multisensory glory.
这种特定的细胞模式，所有细胞一起工作就是现有的记忆，是多感官相融合。
The word scientists use to talk about this physical trace of a memory in a brain, the pattern of cells that activate to recall a memory, is an engram.
科学家用来谈论大脑中记忆的物理痕迹，即激活回忆记忆的细胞模式，是一个记忆印迹。
It's the unique pattern of cells activating together across the brain that makes a memory.
正是大脑中细胞共同激活的独特模式造就了记忆。
And these cells are actually changed by the learning experience.
这些细胞实际上被学习经验所改变。
They form stronger connections with each other than with other neurons
它们之间的联系比其他神经元更强，
and they develop more dendritic spines: protrusions that help neurons talk to each other.
而且还发育出更多突触小棘，这些是帮助神经元相互交流的突起。
So how do you find an engram?
那怎么找到记忆印迹？
Ideally, if you could watch neurons fire, you should see the same ones fire when the same memory is activated.
理想情况下，如果能观察到神经元放电，当同样的记忆被激活时，应该能看到相同的神经元被激活。
And we can do that in mice.
我们能在老鼠身上这样做。
In a 2007 study published in the journal Science, researchers taught a mouse to associate a mild foot shock with a sound.
2007年发表在《科学》期刊上的一项研究中，研究人员让一只老鼠把轻微的脚震和一种声音联系起来。
This is a pretty commonly used protocol for studying memory.
这是研究记忆很常用的一种方案。
If you see the mouse tense up, you know it remembers a shock is coming.
如果你看到老鼠紧张起来，就知道它记住了电击即将来临。
And don't worry, it's just, it's like a little zap.
别担心，就像是一个遥控器。
The researchers used a special glowing protein to tag the neurons that fired as the mouse learned.
研究人员用一种特殊的发光蛋白质，标记老鼠学习过程中激发的神经元。
That let them monitor what neurons fired when the mouse heard the tone and remembered what was coming next.
老鼠听到声音并记住接下来发生的事时，研究人员能监控神经元的活动。
A few days later, when the researchers played the sound again, they saw the same neurons firing.
几天后，当研究人员再次播放这个声音时，他们看到同样的神经元在放电。
Basically, they saw that memory.
基本上，他们看到了那种记忆。
Now the next question was whether altering the neurons in the engram would mess with the memory.
下一个问题是改变记忆印迹中的神经元，是否会扰乱记忆。
Which would prove that those neurons were holding that memory, and could even lead to, like, memory editing.
这将证明这些神经元保存着记忆，甚至可能导致记忆编辑。
So in a 2009 study, also in Science, researchers infected an area of the mouse's brain with a virus that increased both how readily those neurons would activate,
因此，在2009年的《科学》期刊上的一项研究中，研究人员用一种病毒感染老鼠大脑的一个区域，这种病毒既增加了神经元激活的速度，
and the number of those neuron-connecting dendritic spines.
也增加了连接突触小棘的神经元数量。
The virus basically made this area full of "super-neurons," which the researchers hoped would be very likely to be used for storing a memory.
病毒基本上使这个区域充满“超级神经元”，研究人员希望这些神经元很可能被用来储存记忆。
Then, the researchers once again taught a mouse to associate between a sound and a foot shock,
随后，研究人员再次教老鼠如何将声音和脚震联系起来。
and then, just as planned, the super-neurons were used to store that memory.
正如计划的那样，超级神经元被用来存储这种记忆。
But the virus also had a kill-switch, which the researchers activated after training.
但是病毒也有一个断路开关，研究人员在训练后可将其激活。
Like a tiny viral assassin, it took out the super-neurons.
它就像一个小小的病毒杀手，杀死了超级神经元。
When they played the sound again, the mouse didn't freeze up.
他们再次播放声音时，老鼠并没有冻僵。
It seemed to have no idea that a shock was coming.
它似乎不知道会有电击。
It appeared that killing those specific cells also killed the memory.
似乎杀死那些特定的细胞，也会破坏记忆。
In subsequent research, scientists were able to manipulate both real and false memories.
在随后的研究中，科学家们能够操纵真实和错误的记忆。
In one 2012 study, the researchers used a technique called optogenetics,
在2012年的一项研究中，研究人员使用一种叫做光遗传学的技术，
where, by shining a special light on a part of the brain primed with light-sensitive proteins, you can turn specific neurons on.
通过将一种特殊的光照在大脑中被感光蛋白激活的部分，能激活特定的神经元。
The researchers taught a mouse to associate a sound with a shock and then pumped the engram cells,
研究人员教一只老鼠把声音和电击联系起来，
where they knew that memory lived, full of this light-sensitive protein.
然后给他们所知道的记忆存在的部位注入记忆印迹细胞，细胞中充满这种感光蛋白。
When they turned on the light, the mouse acted like it had just heard the sound and expected a shock, even though there was no sound.
他们打开灯时，老鼠表现得好像刚听到了声音，并预期会出现点击，即使当时没有声音。
And in a 2013 study published in Science, researchers moved a mouse from an old cage to a new cage,
2013年发表在《科学》期刊上的一项研究中，研究人员将一只老鼠从旧笼子移到新笼子里，
and trained it to fear that new cage with electric shocks.
并训练它害怕新笼子里的电击。
Then, they used similar optogenetic techniques to make the mouse remember its old cage while it was in the new one.
然后，他们利用类似的光遗传学技术，让老鼠在新笼子里时想起旧笼子。
When they put the mouse back in its old cage, it still seemed frightened; it thought that was where the shock had happened.
他们把老鼠放回旧笼子里时，它看起来仍然很害怕，因为旧笼子里会有电击。
These findings might make it seem like neuroscientists are officially masters of memory, able to edit, implant, and delete memories at a whim.
这些发现可能让人觉得神经科学家是记忆的权威，他们能随心所欲地编辑、植入和删除记忆。
But it is very early days here.
但现在还为时尚早。
We're nowhere close to handheld memory wiping gadgets à la Men in Black.
我们根本不可能像《黑衣人》电影里那样，用手提电脑擦拭记忆。
But, if manipulating engram cells can add, delete, and modify memories in predictable ways,
但是，如果操纵记忆印迹细胞能以可预测的方式增加、删除和修改记忆，
that does mean engrams are a useful model for studying memory.
那就意味着记忆印迹是研究记忆的有用模型。
Memory is such a crucial part of our lives and our identities, and by better understanding how it works physically, we demystify it.
记忆是我们生活和身份的重要组成部分，通过更好地理解记忆的生理功能，我们能揭开它的神秘面纱。
That could open the door for better treatments for conditions like Alzheimer's or post-traumatic stress disorder.
这可能为更好地治疗老年痴呆症或创伤后应激障碍打开大门。
So while we will probably never have zappers to remind us where our keys went,
因此，虽然我们可能永远不会有遥控器来提醒自己钥匙去哪儿了，
we are getting closer to understanding how our brains store the memories that make us, us.
但我们越来越接近于理解大脑是如何储存那些造就我们的记忆。
Thanks for watching this episode of SciShow Psych.
感谢收看本期《心理科学秀》。
Did you know you can help us make fascinating videos about science that are free for the whole Internet to enjoy?
你知道吗，你能帮我们制作精彩的科学视频，让人们在整个互联网上免费观看吗？
Because you can, if you become a patron!
你成为赞助人，就可以这么做！
And if you do, you will be joining an amazing community of people, and scoring neat perks like behind-the-scenes bloopers.
如果你这样做，你将加入一个超棒的社区，并获得像幕后黑手一样丰厚的福利。
I had some in our recent episode about robots. I got real mad about a thing.
我在最新一集关于机器人的视频中得到了一些这样的福利，我特别激动。
If you're interested, head over to patreon.com/scishow.
如果你感兴趣，可以登录patreon.com/scishow网站。
