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We've all been there -- tossing and turning all night for absolutely no reason.
我们都有过这种经历——毫无理由地辗转反侧一整个晚上。
But for the vast majority of people, insomnia can't actually kill you.
但对绝大多数人来说，失眠并不能真正杀死你。
In one very rare, very specific case, however, not only is insomnia deadly -- it's lurking in your genes from the time you're born.
然而，在一个非常罕见、特殊的案例中，失眠不仅致命——它潜伏在你出生时的基因中。
Familial fatal insomnia, or FFI, is an incredibly rare condition where patients experience lack of sleep and other psychiatric symptoms, and eventually die.
家族致命性失眠症（FFI）是一种极其罕见的疾病，患者会出现睡眠不足和其他精神症状，最终死亡。
And though we know what causes it, there's a lot about that cause we don't fully understand.
虽然我们知道其原因，但有很多原因我们还不完全理解。
Familial fatal insomnia usually affects adults as early as their 30s,
家族性致命性失眠症通常最早影响到30多岁的成年人，
though there have been a very small number of cases in teenagers.
尽管在青少年中有很少的病例。
And yes -- it is fatal.
是的，这种疾病可以致命。
Unfortunately, there's no cure, and patients usually die within a year or two of showing symptoms.
不幸的是，没有治愈方法，病人通常在出现症状后一两年内死亡。
It usually starts when people report having a hard time falling or staying asleep.
它通常始于人们报告难以入睡或保持清醒的状态。
When they do sleep, they have a harder time achieving deep, restful sleep.
他们睡觉时，很难达到深度、平静的睡眠。
And their brain activity actually changes.
他们的大脑活动实际上也会发生改变。
The typical sleep cycles most people experience are altered for these patients.
大多数人所经历的典型睡眠周期，都会因这些病人而改变。
Sometimes their perceptions while awake during the day can become dream-like,
有时，他们白天清醒时的感知会变成梦一样，
either hallucinating, seeing double, or reacting to things in the dream.
或产生幻觉，或是看到两个幻觉，或是对梦中的事物做出反应。
As the disease progresses, patients develop problems with balancing and walking, and experience actual dreams throughout the day.
随着病情的发展，患者在平衡和行走方面出现问题，并在一整天中体验到真实的梦境。
But FFI is so rare that these symptoms can be really misleading.
但FFI非常罕见，这些症状可能是误导。
If a patient comes in complaining of hallucinations, for example, doctors might be more likely to think of something like schizophrenia.
例如，如果患者抱怨出现幻觉，医生可能更容易想到精神分裂症之类的病症。
Because FFI is incredibly rare.
因为FFI非常罕见。
Only a few dozen cases have been described in the medical literature, though it might be slightly more common than that.
医学文献中只描述过几十个病例，尽管它可能比这更常见一些。
So where does this disease come from?
这种病从何而来呢？
Well, autopsies of patients with this disease show something in common -- deterioration of tissue in the thalamus.
对这种病患者的尸检显示出一些共同点——丘脑组织的恶化。
This region is often called a relay center, connecting different parts of the brain to each other.
该区域通常称为中继中心，将大脑的不同部分连接起来。
But it plays a specific role in regulating your sleep cycles.
但它在调节睡眠周期中起着特殊的作用。
It's involved in monitoring sensory information like vision,
它参与监控视觉等感官信息，
and seems to serve as a gate that chooses when to let that information pass to other parts of your brain.
似乎是选择何时让这些信息传递到大脑其他部位的大门。
Meaning it may help you become less aware of your surroundings as you drift off.
这意味着当你在迷迷糊糊的状态时，它能帮你减少对周围环境的感知。
So why do some people get this thalamus deterioration?
为什么有些人丘脑会退化？
That brings us to the "familial" part of the name -- it's genetic, and we know just which gene is to blame.
这就引出了其名字中的“家族性”部分。这种疾病具有遗传性，我们知道该归咎于哪个基因。
FFI is a prion disease -- specifically, an inherited one.
FFI是一种朊病毒疾病，特别是一种遗传性疾病。
These are a handful of rare diseases that cause neural degeneration, all associated with a specific protein called the prion protein.
这些都是少数导致神经退化的罕见疾病，都与一种叫做朊蛋白的特殊蛋白质有关。
That protein is coded for by a gene called PRNP.
这种蛋白质是由一种叫做PRNP的基因编码。
Variants of this gene can make the protein mutate, which causes all kinds of problems for your brain tissue.
这种基因的变异会使蛋白质发生变异，从而给大脑组织带来各种各样的问题。
Quite a few variants in this gene have been documented,
在这个基因中有相当多的变异已经被证实，
but only one results in the specific deterioration in the thalamus associated with FFI.
但是只有一种导致与FFI相关的丘脑的特异性恶化。
And in patients with FFI, you can find this mutated protein in the deteriorated parts of the thalamus.
在患有FFI的患者中，能在丘脑恶化的部位发现这种突变蛋白。
Another prion disorder, Creutzfeldt-Jakob disease, also follows a similar pattern
另一种朊病毒疾病，克雅氏病，也遵循类似的模式。
-- but targets different brain regions that affect memory, coordination, and vision.
但其目的是影响记忆、协调和视觉的不同脑区。
We're not exactly sure how this misshapen protein causes neural degradation,
我们还不清楚这种畸形蛋白如何导致神经退化，
but some researchers think it involves the body's natural process of programmed cell death.
但一些研究人员认为，它涉及人体细胞程序性死亡的自然过程。
Damaged brain regions like the thalamus look like they died from apoptosis
受损的大脑区域，比如丘脑，看起来像死于细胞凋亡，
-- but the protein can be detected outside of where the damage is.
但是这种蛋白质能在受损区域之外检测到。
Which gets to the big mystery about this disease: we don't really know why we have this protein in the first place.
这就引出了这种疾病的一个大谜团：我们不知道出现这种蛋白质的原因。
We really only tend to notice it when it goes wrong -- deteriorating neural tissue and ultimately leading to death.
我们只会在它出现问题的时候注意到它，神经组织恶化，最终导致死亡。
If it's not doing anything terribly important when everything's ok,
如果它在一切正常时，没有做任何非常重要的事，
but does horrible things when it mutates, you'd think evolution would get rid of it.
但在变异时却出现了可怕的事情，你会认为进化将把它去掉。
But it's found in other mammals and birds as well as humans, suggesting there could be a good reason to keep it around.
但在其他哺乳动物、鸟类以及人类身上也发现过这种病毒，这表明其存在有很好的理由。
We just don't know what that is.
我们只是不知道其原因。
Some studies in mice have found that when they have less of the regular, unmutated prion protein,
一些用老鼠进行的研究发现，当它们含有较少的常规性、未突变的朊蛋白时，
they have less long-term potentiation in the hippocampus -- though those results haven't been consistent.
它们在海马体中的长期增强作用就会减弱，尽管这些结果并不一致。
Long-term potentiation is the idea that when a neuron fires repeatedly,
长时程增强是指当一个神经元反复激发时，
it forges stronger synaptic connections, which is theorized to be an important part of how memory works.
它会形成更强的突触连接，这在理论上是记忆工作的一个重要部分。
Furthermore, when mice have more of this protein than usual, they have even more synaptic transmission.
此外，当老鼠拥有的这种蛋白质比平时更多时，它们会有更多的突触传递。
So, possibly stronger memories.
所以，记忆力可能更强。
Messing with the amounts of a protein to see what changes is scientists' favorite method for figuring out what that protein does normally.
科学家们最喜欢的研究方法，是通过改变蛋白质的含量来了解蛋白质的正常功能。
These experiments tell us the prion protein could be critical for keeping your memory functioning, but not all studies actually agree.
这些实验告诉我们，朊蛋白对保持记忆功能至关重要，但并不是所有的研究结果都一致。
Another idea is that the common prion protein is just doing the opposite of what the misshapen one does
另一种观点是，普通朊蛋白的作用与畸形蛋白的作用正好相反。
-- instead of killing our neural tissue, it's protecting it.
它不会杀死我们的神经组织，反而是保护它。
In those same kinds of more-or-less-protein experiments,
在这些相同种类或有些许蛋白质实验中，
mice bred to not have the prion protein would suffer larger lesions when researchers induced a stroke compared to normal mice.
当研究人员诱发出中风时，没有朊病毒蛋白的小鼠会比正常小鼠遭受更大的损伤。
And having more of that protein seemed to protect against neural damage.
而且，含有更多的这种蛋白质似乎可以防止神经损伤。
So it's possible that having a better understanding of this protein might unlock some ideas about why brains deteriorate as they age.
因此，对这种蛋白质有更好的理解，可能会解开一些关于大脑随年龄增长而退化的想法。
While research is ongoing about what makes this protein work,
虽然正在进行的研究是有关什么使这种蛋白质起作用，
it could help us understand how memory works and how to prevent some of the neural changes associated with aging.
但它能帮助我们了解记忆的工作方式，以及如何防止一些与衰老相关的神经变化。
Which could help us treat more common diseases like Alzheimer's and MS, but also help those few people who develop fatal insomnia.
这能帮我们治疗更常见的疾病，如老年痴呆症和多发性硬化症，但也能使少数人发展出致命的失眠症。
Thanks for watching this episode of SciShow Psych,
感谢收看本期《心理科学秀》节目，
which was brought to you with the help of our community of amazing patrons.
在令人惊叹的赞助人社区的帮助下，我们为您制作出本期节目。
We couldn't make SciShow without your help, so thanks!
没有你们的帮助，我们无法制作出科学秀，感谢你们！
If you want to get involved, check out patreon.com/scishow.
如果你想参与其中，请登录网站：patreon.com/scishow。
