Our memories are imperfect.
我们的记忆不完美。
You can probably recall who you spoke to over dinner last weekend but have likely forgotten the details of the conversation.
你可能记得上个周末吃饭时和谁说过话，但很可能忘记了谈话的细节。
Remembering too much can have its downsides—in conditions such as post-traumatic stress disorder, a distressing event can remain imprinted in an individual’s mind, causing continued anguish.
记忆过多也有其不利之处-在创伤后应激障碍等情况下，令人痛苦的事件可能会一直印在一个人的脑海中，导致持续的痛苦。
On the other hand, excessive memory loss is also a problem.
另一方面，过度的记忆丧失也是一个问题。
Alzheimer’s disease, for example, is marked by an inability to recollect.
例如，阿尔茨海默氏症的特点是无法回忆。
Using mice, scientists have now demonstrated that the brain’s resident immune cells, microglia, play a critical role in helping the organ to forget.
利用老鼠，科学家们现在已经证明了大脑中驻留的免疫细胞，小胶质细胞，在帮助器官忘记方面起着至关重要的作用。
Microglia were once seen solely as the brain’s watchdogs—activated exclusively to guzzle pathogens and dead and dying neurons.
小胶质细胞曾经只被视为大脑的看门狗-专为吞噬病原体和死亡的神经元而激活。
That view has changed in recent years, as scientists have amassed evidence that these cells have wide-ranging duties: During development, they seem to help sculpt the brain by trimming away excess synapses—the connections between neurons.
近些年来，这种观点发生了变化，因为科学家们积累了证据，证明这些细胞具有广泛的职责：在发育过程中，它们似乎通过修剪掉多余的突触-神经元之间的连接-来帮助塑造大脑。
And microglia appear to be major players in several neurodevelopmental and neurodegenerative diseases, including autism and Alzheimer’s.
小胶质细胞似乎是几种神经发育和神经退行性疾病的主要参与者，包括自闭症和阿尔茨海默氏症。
Yan Gu, a neuroscientist at the Zhejiang University School of Medicine in China, says he and his colleagues were intrigued by the potential link between the work on microglial pruning during early development and prior research indicating that synapses are important for the storage and coding of memories.
中国浙江大学医学院的神经科学家严谷(音译)表示，他和他的同事们对早期发育期间关于小胶质细胞修剪的工作与先前的研究之间的潜在联系感到好奇，这表明突触对于记忆的存储和编码很重要。
“We wondered whether microglia can eliminate synapses in the adult brain,” he says.
“我们想知道小胶质细胞是否可以消除成人大脑中的突触，”他说。
“And what is the relationship between loss of synapses by microglia and forgetting?”
“小胶质细胞失去突触和遗忘之间有什么关系？”
To address this question, Gu’s group teamed up with other researchers at Zhejiang University in a study, including neuroscientist Lang Wang. They depleted microglia from the brains of mice with drugs administered either through food or injected directly into the brain.
为了解决这个问题，顾的团队在一项研究中与浙江大学的其他研究人员合作，其中包括神经学家朗·王。他们用通过食物或直接注射到大脑中的药物从小鼠的大脑中耗尽小胶质细胞。
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