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小贴士：
本期为接上期内容，新来的朋友们请翻开历史消息查看上篇内容哦～
——大橙子留
上期翻译答案
Any successful learning system, be it a brain or a piece of artificial-intelligence software, must strike the right balance between stability and flexibility.
无论是大脑还是人工智能软件，任何成功的学习系统都必须在稳定和灵活之间取得恰当的平衡。
《本期内容》
双语阅读
To carry out their search for filopodia, the trio used a sensitive microscopy technique called eMAP. They studied 2,234 synapses betweencorticalnerve cells of a type called pyramidal neurons, which have thousands of synapses each.Peeringthrough an eMAP microscope is enough to determine which cellularprotrusionsare filopodia. But it cannot show which synapses on them are silent.
为了寻找树突丝，三位研究人员使用了一种名为“蛋白质组表位保存放大分析”的灵敏显微镜成像技术。他们研究了2234个被称为锥体神经元的处在皮质神经细胞之间的突触，每个锥体神经元有数千个突触。通过蛋白质组表位保存放大分析显微镜观察足以确定哪些细胞突起是树突丝。但无法确定树突丝上的哪些突触是沉默突触。
To do that, they needed to test how the filopodia responded toglutamate, the brain’s main excitatory neurotransmitter. First, they had to deliver a controlled flow of glutamate to the particular synapse they wanted to test. To this end, they poured a soup of “caged” glutamate over the neuron under examination. This form of the molecule isinertuntil hit with energy from the intersection of two laser beams.
要做到这一点，他们需要测试树突丝对谷氨酸的反应，谷氨酸是大脑主要的兴奋性神经递质。首先，他们必须向他们想要测试的特定突触输送一定量的谷氨酸。为此，他们将一部分盛装起来的谷氨酸汤倒在受检查的神经元上。这种形式的分子通常是惰性的，除非受到两股激光交汇的能量冲击。
Aiming those at the synapse under study enabled them to uncage the neurotransmitter and see, by measuring the electrical activity in that part of the neuron using an ultrafine electrode, whether the synapse responded. They found that mature pyramidal-neuron protrusions generated electrical activity when exposed to glutamate, as expected. Filopodia did not, confirming the silence of their synapses.
把谷氨酸对准被研究的突触，使其能够释放神经递质，并通过使用超精细电极测量这部分神经元发出的电活动，来观察突触是否有反应。正如预期的那样，他们发现成熟的锥体神经元突起暴露在谷氨酸中产生了电活动。树突丝则没有，这证实了它们的突触是沉默突触。
Silent synapses are, however, useless unless they can beswitched onat the appropriate moment. And the researchers confirmed this is possible. They were able to induce the silent versions on filopodia to turn into mature, active synapses by pairing the simulated release of glutamate with a subsequent surge of electricity inside the neuron. This pairing of events caused silent synapses to start, within minutes, displaying receptor molecules characteristic of active synapses.
然而，除非沉默突触在恰当的时候被激活，否则它们平时是没用的。研究人员证实，激活沉默突触是有可能的。翻译划线句，长按文末小程序码打卡，答案下期公布~这种结合配对事件可以让沉默突触在几分钟内被激活，显示出活跃突触特有的受体分子。
The same pairing, applied to mature synapses, did nothing. The researchers thereby show it is hard to get a mature synapse to change the strength of its connection (thus satisfying the stability side of the dilemma), but easy to unsilence a silent one (satisfying the plasticity side).
同样的结合配对，应用于成熟突触却没有任何作用。研究人员由此确定，改变成熟突触连接的强度很难（因此能够实现平衡性中稳定性的要求），但激活沉默突触是很容易的（因此满足平衡性中可塑性的要求）。
本文节选自：The Economist（经济学人）
发布时间：2023.01.05
作者：Science and Technology
原文标题：How adult brains learn the new without forgetting the old
词汇积累
1. cortical
/’kɔrtɪkl/
adj.皮质的；[生物] 皮层的；外皮的
2. peer
/pɪə/
n. 同龄人，同等地位的人，相匹敌的人
v. 凝视，费力地看; 隐现
3. protrusion
/prəˈtruːʒən/
n.突出；突出物
4. glutamate
/ˈɡluːtəˌmeɪt/
n.谷氨酸盐；谷氨酸酯
5. inert
/ɪnˈɜːt/
adj.[化学] 惰性的；呆滞的；迟缓的；无效的
词组搭配
1.switch on 接通，开启
写作句总结
Silent synapses are, however, useless unless they can be switched on at the appropriate moment.
结构：… are, however, useless unless they can be switched on at the appropriate moment.
然而，除非…在恰当的时候被激活，它们平时是没用的。
例句：Some specific chips are, however, useless unless they can be switched on at the appropriate moment.
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