生物时钟与记忆：遗忘取决于所处时间
Can't remember something?Try waiting until later in the day.Researchers identified a gene in mice that seems to influence memory recall at different times of day and tracked how it causes mice to be more forgetful just before they normally wake up.
不记得了吗?等晚些时候再试试。研究人员在小鼠中发现一个在不同时间影响记忆的基因。该基因使小鼠在正常睡醒前变得更健忘。
"We may have identified the first gene in mice specific to memory retrieval,"said Professor Satoshi Kida from the University of Tokyo Department of Applied Biological Chemistry.
东京大学应用生物化学系的Satoshi Kida教授说：“我们可能是第一个在小鼠中找到记忆检索基因。”
Every time you forget something,it could be because you didn't truly learn it--like the name of the person you were just introduced to a minute ago;or it could be because you are not able to recall the information from where it is stored in your brain--like the lyrics of your favorite song slipping your mind.
每当您忘记某件事时，可能是因为您没有真正学习到它-就像一分钟前刚被介绍给您的人的名字一样;或可能是因为您无法从大脑中存储的信息中回想起信息-就像您喜欢的歌曲的歌词使您难以置信。
Many memory researchers study how new memories are made.The biology of forgetting is more complicated to study because of the difficulties of distinguishing between not knowing and not recalling.
许多记忆研究人员研究新记忆的产生方式。由于难以区分不知道和不记得，因此遗忘的生物学研究更为复杂。
Researchers tested the memories of young adult male and female mice.In the"learning,"or training,phase of the memory tests,researchers allowed mice to explore a new object for a few minutes.
研究人员测试了成年雄性和雌性小鼠的记忆。在记忆测试的“学习”或训练阶段，研究人员允许小鼠在几分钟内探索一个新物体。
Later,in the"recall"phase of the test,researchers observed how long the mice touched the object when it was reintroduced.Mice spend less time touching objects that they remember seeing previously.Researchers tested the mice's recall by reintroducing the same object at different times of day.
后来，在测试的“召回”阶段，研究人员观察了老鼠在重新回忆起物体前触摸了多长时间。小鼠花在触摸他们之前记得看过的物体上的时间更少。研究人员通过在一天的不同时间重新引入同一物体来测试小鼠的回忆率。
健康小鼠和不含BMAL1的小鼠进行了相同的实验
They did the same experiments with healthy mice and mice without BMAL1,a protein that regulates the expression of many other genes.BMAL1 normally fluctuates between low levels just before waking up and high levels before going to sleep.
他们对健康小鼠和不含BMAL1的小鼠进行了相同的实验，BMAL1是一种调节许多其他基因表达的蛋白质。BMAL1通常在醒来前的低水平和睡觉前的高水平之间波动。
Mice trained just before they normally woke up and tested just after they normally went to sleep did recognize the object.
通常在刚醒来之前接受训练的小鼠，以及在刚入睡后进行测试的小鼠，都能识别出该物体。
Mice trained at the same time--just before they normally woke up--but tested 24 hours later did not recognize the object.
老鼠是在同一时间训练的-就在它们通常醒来之前-但经过24小时的测试却无法识别出该物体。
Healthy mice and mice without BMAL1 had the same pattern of results,but the mice without BMAL1 were even more forgetful just before they normally woke up.Researchers saw the same results when they tested mice on recognizing an object or recognizing another mouse.
健康小鼠和不含BMAL1的小鼠具有相同的结果模式，但不含BMAL1的小鼠在正常醒来之前甚至更加健忘。当研究小鼠识别物体或识别另一只小鼠时，研究人员看到了相同的结果。
Something about the time of day just before they normally wake up,when BMAL1 levels are normally low,causes mice to not recall something they definitely learned and know.
当BMAL1水平通常很低时，通常在一天中它们醒来之前的某个时间，会导致小鼠不记得他们肯定学习和知道的东西。
Researchers have traced the role of BMAL1 in memory retrieval to a specific area of the brain called the hippocampus.Additionally,researchers connected normal BMAL1 to activation of dopamine receptors and modification of other small signaling molecules in the brain.
研究人员已将BMAL1在记忆检索中的作用追溯到大脑特定区域称为海马体。此外，研究人员将正常的BMAL1与多巴胺受体的激活以及大脑中其他小信号分子的修饰联系起来。
"If we can identify ways to boost memory retrieval through this BMAL1 pathway,then we can think about applications to human diseases of memory deficit,like dementia and Alzheimer's disease,"said Kida.
Kida说：“如果我们能够找到通过这种BMAL1途径促进记忆恢复的方法，那么我们就可以考虑将其应用于人类记忆缺陷的疾病，例如痴呆症和阿尔茨海默氏病。”
However,the purpose of having memory recall abilities that naturally fluctuate depending on the time of day remains a mystery.
但是，记忆能力根据一天中的时间自然波动的的目的仍然是个谜。
"We really want to know what is the evolutionary benefit of having naturally impaired memory recall at certain times of day,"said Kida.
Kida说：“我们真的想知道在一天中的某些时候将自然受损的记忆召回的进化益处是什么。”
About the research
研究情况简介
Mice are naturally nocturnal.When measured in units of time using zeitgeber,the environmental cue of light turning on,mice are usually asleep from Zeitgeber Time 1 to 12 and awake from Zeitgeber Time 12 to 24.The term"just before normally waking up"refers to Zeitgeber Time 10,while the term"just after normally going to sleep"refers to Zeitgeber Time 4.
小鼠自然是夜间活动的。当使用Zeitgeber(开启光的环境提示)以时间为单位进行测量时，小鼠通常在Zeitgeber时间1到12处于睡眠状态，而在Zeitgeber时间12到24处于唤醒状态。术语“就在正常醒来之前”指的是Zeitgeber时间10，而术语“刚睡后”指的是Zeitgeber时间4。
Collaborators at the Tokyo University of Agriculture and the University of Toronto also contributed to this research.
东京农业大学和多伦多大学的合作者也为这项研究做出了贡献。
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