Our memories are imperfect.
我們的記憶不完美。
You can probably recall who you spoke to over dinner last weekend but have likely forgotten the details of the conversation.
你可能記得上個週末吃飯時和誰說過話，但很可能忘記了談話的細節。
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.
記憶過多也有其不利之處-在創傷後應激障礙等情況下，令人痛苦的事件可能會一直印在一個人的腦海中，導致持續的痛苦。
On the other hand, excessive memory loss is also a problem.
另一方面，過度的記憶喪失也是一個問題。
Alzheimer’s disease, for example, is marked by an inability to recollect.
例如，阿爾茨海默氏症的特點是無法回憶。
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，科學家們現在已經證明了大腦中駐留的免疫細胞，小膠質細胞，在幫助器官忘記方面起著至關重要的作用。
Microglia were once seen solely as the brain’s watchdogs—activated exclusively to guzzle pathogens and dead and dying neurons.
小膠質細胞曾經只被視為大腦的看門狗-專為吞噬病原體和死亡的神經元而激活。
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.
近些年來，這種觀點發生了變化，因為科學家們積累了證據，證明這些細胞具有廣泛的職責：在發育過程中，它們似乎通過修剪掉多餘的突觸-神經元之間的連接-來幫助塑造大腦。
And microglia appear to be major players in several neurodevelopmental and neurodegenerative diseases, including autism and Alzheimer’s.
小膠質細胞似乎是幾種神經發育和神經退行性疾病的主要參與者，包括自閉症和阿爾茨海默氏症。
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.
中國浙江大學醫學院的神經科學家嚴谷(音譯)表示，他和他的同事們對早期發育期間關於小膠質細胞修剪的工作與先前的研究之間的潛在聯繫感到好奇，這表明突觸對於記憶的存儲和編碼很重要。
“We wondered whether microglia can eliminate synapses in the adult brain,” he says.
“我們想知道小膠質細胞是否可以消除成人大腦中的突觸，”他說。
“And what is the relationship between loss of synapses by microglia and forgetting?”
“小膠質細胞失去突觸和遺忘之間有什麼關係？”
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.
為了解決這個問題，顧的團隊在一項研究中與浙江大學的其他研究人員合作，其中包括神經學家朗·王。他們用通過食物或直接注射到大腦中的藥物從小鼠的大腦中耗盡小膠質細胞。
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