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We've all learned that neurons are one of the main building blocks of your brain.
我们都知道，神经元是大脑的主要组成部分之一。
They shuttle along information so you can think and feel and remember and do things.
它们往来传递信息，这样你就能思考、感觉、记忆与做事了。
Neurons communicate with each other using chemicals called neurotransmitters,
神经元用于相互交流的化学物质叫做神经递质，
which get passed through a gap called a synaptic cleft.
后者能通过突触间隙。
Now, this way of communication has been the basis for a lot of research into brain chemistry,
现在，这种交流方式已经成为众多脑化学研究的基础，
and it has massively influenced how we design medicines that target the brain.
极大地影响着我们针对脑部的药物研究设计。
But scientists have observed a new way that neurons can pass information.
但是科学家们注意到了一种神经元传递信息的新方式。
It's pretty groundbreaking… and it's pretty weird.
它非常具有开创性，而且很奇怪。
All this excitement centers around the Arc gene.
所有这些兴奋发现都是关于Arc基因的。
Like many genes, it encodes a string of mRNA which encodes a protein.
Arc基因与许多基因一样，它编码一连串能编码蛋白质的信使核糖核酸（mRNA）。
And Arc has been studied in relation to memory and learning.
研究表明，Arc与记忆和学习有关。
After a neuron fires, which is when an electrical signal gets sent through the cell,
神经元被激活后，即电信号通过细胞发出后，
the Arc protein and mRNA build up in the cell's dendrites.
Arc蛋白和mRNA在细胞的树突中形成。
These are the branches that connect one neuron to others,
树突是连接一个神经元与其他神经元的分叉，
usually by receiving neurotransmitters.
通常接收神经递质。
Arc's full name is activity-regulated cytoskeleton-associated protein,
Arc的全名叫做活性调节的细胞骨架相关蛋白，
because it's involved in changing a neuron's cytoskeleton,
因为它参与改变神经元的细胞骨架,
the network of proteins that gives cells their structure.
细胞骨架是指形成细胞结构的蛋白质网。
We think this helps reinforce connections between neurons, which helps us hold on to information.
我们认为它有助于加强神经元之间的联系，帮助我们保持信息。
Stronger connections mean stronger memories.
联系更强意味着记忆更强。
And without the Arc gene, we might not be able to remember new things as easily.
没有Arc基因，我们可能无法轻易记住新事物。
In a study from 2000, researchers conducted some experiments involving the Arc gene in rats.
在2000年的一项研究中，研究人员用携带Arc基因的老鼠进行了一些实验。
They used 42 male rats, half of which were dosed with a compound that messed with Arc mRNA
他们使用了42只雄鼠，其中一半服用了含Arc信使核糖核酸的化合物，
and kept them from making proteins.
并阻止它们制造蛋白质。
The other half got a control dose that didn't affect Arc.
另一半服用了不影响Arc的控制试剂。
After the brain treatment, the rats were trained to find a hidden platform in a tank filled with water.
经过大脑治疗，老鼠们被训练在装满水的水箱里找一个隐藏的平台。
All the rats did fine after a couple practice rounds, Arc protein or not.
不管有没有Arc蛋白质，所有的老鼠在经过几轮训练后都表现良好。
But then, 48 hours later, they were all tested on their ability to find the platform again.
但是48小时后，他们又被测试再次找到平台的能力时，
And rats that had the Arc-inhibiting dose in their brains did worse than the control group,
那些大脑中有Arc抑制剂的老鼠比对照组表现的糟糕，
which the researchers took to mean that they had trouble forming memories of the practice.
研究人员认为，这意味着它们很难形成对这种训练的记忆。
In a separate experiment, they tried dosing rats with the compounds 8 hours after the training session.
在另一项实验中，研究人员在训练结束8小时后给老鼠服用了混合试剂，
And both groups of rats did about the same on the test!
结果两组老鼠在实验中表现相同！
So this makes Arc seem especially important while the rats were learning the task and forming those neural pathways.
因此实验表明，当老鼠学习任务并形成这些神经通路时，Arc显得尤为重要。
Now, this bit of research in itself is neat.
这项研究本身很巧妙。
But Arc is also interesting in human brains, even though we're not entirely sure what it's doing.
但是人类大脑中的Arc也很有趣，尽管我们并不完全确定它的作用。
Abnormal levels of Arc protein have been found in patients with Alzheimer's disease.
我们发现，阿尔茨海默病患者体内的Arc蛋白水平异常。
And studies with genetic analyses have suggested that Arc gene variants may play a role in schizophrenia.
而且遗传分析研究表明，Arc基因变异可能在精神分裂症中起作用。
And then there's the Arc research that's changing how scientists think about brains altogether.
随后Arc的研究改变了科学家们对大脑的看法。
In a paper published in January 2018 in the journal Cell,
在2018年1月发表于《细胞》杂志上的一篇论文中，
researchers from the University of Utah described their most recent work on the Arc gene,
犹他大学的研究人员描述了他们最近在Arc基因上的研究，
when things took an unexpected turn.
这时事情出现了意外转机。
The first big surprise was when they looked at some engineered bacteria
第一个大惊喜是，他们在研究一些
that were churning out Arc proteins from a rat gene.
大量制造由老鼠基因产生的Arc蛋白的工程菌时，
They noticed that Arc was clumping up into structures that looked weirdly like capsids,
注意到，Arc聚集成看起来很怪的衣壳结构，
tiny protein capsules that protect the genetic information of viruses.
衣壳是指保护病毒遗传信息的微小蛋白胶囊。
Not only that, but more tests showed that
不仅如此，更多的测试表明，
Arc capsids form little packages around Arc mRNA and other RNA that might be hanging out in cells.
Arc衣壳在其mRNA以及常进细胞的其他核糖核酸（RNA）周围形成小包，
Which is also like viruses.
这也和病毒一样。
Then, the scientists tried sticking the Arc proteins in a bunch of mouse neurons
然后，科学家们尝试在一堆老鼠神经元中加入Arc蛋白质，
and noticed that capsids were actually shuttling mRNA between cells.
并注意到，衣壳实际在细胞之间运送mRNA。
And with the extra mRNA, the receiving neurons could probably generate even more Arc.
接收神经元利用多余的mRNA可能会产生更多的的Arc。
That's what had researchers floored: Arc capsids crossed synapses.
这就是研究人员的研究成果：Arc衣壳能穿过突触。
They carried information between neurons in a way that we thought was exclusive to neurotransmitters!
它们用一种我们之前认为独属于神经递质的方式在神经元之间传递信息！
And after some genetic analyses, they think that the Arc gene doesn't just act like a virus…
研究人员在进行一些基因分析之后认为，Arc基因并不像病毒一样……
Hundreds of millions of years ago,
几亿年前，
it probably came from a retrovirus ancestor that infected our ancestors and got into our genome.
它可能是感染了我们祖先的逆转录酶病毒祖先，并进入了我们的基因组。
Now, having virus genes stick around in your body might sound a little risky
现在，让病毒基因留在身体里听起来有点儿冒险，
I mean, that's the huge problem with HIV.
我的意思是，这是携带HIV病毒的一大问题。
But some estimates suggest that up to 8% of human DNA could've come from retroviruses.
但一些估计显示，多达8%的人类DNA可能来自逆转录酶病毒。
Most of this DNA has changed enough that it doesn't do anything.
这类DNA大部分已经改变了，没什么危害。
But some researchers have argued that certain viral fragments have been repurposed by our bodies.
但一些研究人员认为，某些病毒碎片已被我们的身体重新利用了。
And now with Arc, we aren't sure how or why our neurons seem to be using these virus-like capsids.
有了Arc的例子，我们不确定神经元为什么使用这些病毒一样的衣壳。
Not to mention, they're not just in the brain.
更不用说它们不仅存在于大脑中了。
In a separate paper published on the same day in the same journal,
在该杂志同一天发表的另一篇论文中，
researchers from the University of Massachusetts reported on Arc capsids crossing synapses in fruit flies.
来自马萨诸塞大学的研究人员报告称，果蝇中有Arc衣壳穿过突触。
But in these experiments they were crossing the neuromuscular junction,
在这些实验中，它们正穿过神经肌肉接点，
where neurons and muscles meet.
即神经元和肌肉的交汇点。
So it seems like Arc could be involved in connections here, too. Not just between neurons.
所以Arc似乎也与这里的连接点有关。不只是在神经元之间。
All these findings are still really new, so scientists have a lot more questions than answers.
这些发现仍旧都是新的，所以科学家们有了更多的疑问，而不是答案。
We still don't really know how this virus-like communication strategy affects memory,
我们仍然不知道这种病毒式的传播策略是如何影响记忆的，
or even what else could be ferried around by Arc capsids.
或者有什么其他东西被Arc衣壳包裹着运输。
Like, what if they help toxic proteins move around the brain,
比如，如果它们能帮助有毒蛋白质在大脑中移动,
which is a major problem with Alzheimer's disease.
那么它将成为阿尔茨海默病的一个主要问题。
So first, researchers studying Arc want to try and repeat these observations.
因此，研究Arc的研究人员首先想尝试并重复这些观察。
And then they'll keep experimenting,
接着，他们会继续实验，
looking in mammals instead of isolated cells or flies to try and find these Arc capsids in action.
通过观察哺乳动物而不是孤立的细胞或苍蝇，试图找到这些活动中的Arc衣壳。
Some scientists think this could open up a new door in treating brain-related illnesses in humans.
一些科学家认为，这将为人类治疗脑相关疾病打开一扇新的大门。
Instead of drugs that target neurotransmitters,
也许，我们终有一天不用研制针对神经递质的药物，
someday we may be able to use Arc capsids to smuggle helpful stuff directly into neurons
能够使用Arc衣壳将有益物质直接带入神经元，
and that would be pretty revolutionary.
而这相当具有革命性。
Thanks for watching this episode of SciShow Psych!
感谢您收看本期的心理科学秀！
And if you want to learn more about memory,
如果你想了解更多关于记忆的内容，
you can check out our other videos on this channel,
可以查看这个频道的其他视频，
like one where we explain whether photographic memory really exists.
比如其中一个解释了过目不忘的能力是否真得存在。
