60秒科学:青春期, 孩子会变笨？

在《科学》杂志上的一篇研究中，研究者们描述了青春期时人体内细胞和分子的改变，正是这种改变促使这段时期的人们智力水平低下。

Ah, puberty. A time for raging hormones, growing independence and being stupid. Okay, not every teenager gets stupid. But they actually do learn less. And in a study published in the journal Science [see Hui Shen et al, http://bit.ly/dbeLY6], researchers describe the cellular and molecular changes that drive this puberty-associated desmartification.

Learning happens in the hippocampus, a brain region that plays a key role in acquiring memories. From a cellular perspective, learning takes place when the connections between nerve cells are strengthened. Interfere with those stronger neuronal connections, and a brain can have trouble laying down new memories. Which, apparently, is what happens in adolescence. At least in mice.

Scientists used a variety of methods to study the brains of pubescent female mice. And they discovered that a particular protein, a kind of GABA receptor, for those of you keeping score at home, crops up in the hippocampus during puberty. These receptor proteins interfere with neuron communication and thus prevent the sort of synaptic strengthening these young animals need to learn.

The good news: a hormone that quiets this pubescent protein turns these young animals back into better learners again. Imagine, a hormone that actually makes an adolescent act smarter.

—Karen Hopkin

啊，青春期！一个荷尔蒙串升的时期，一个增强独立性和变笨的时期。另担心，当然不是每个青少年都会变笨。但是他们确实在那个时期降低了认知水平。并且，在《科学》杂志上的一篇研究中，研究者们描述了青春期时人体内细胞和分子的改变，正是这种改变促使这段时期的人们智力水平低下。

认知开始于海马体，它是大脑中的一个区域，对人类获取知识有着十分重要的作用。从细胞的角度来说，当神经细胞之间的连接加强时，认知便开始了。如果阻断这些强烈的连接，大脑就不能记忆新知识了。很明显，青春期正是有着这样的现象。至少在老鼠中极为普遍。

科学家们使用了许多方法来研究思春期雌性鼠类的大脑。他们意外地在处于青春期的海马体中发现了一种特殊的蛋白质，它是一种GABA （伽马氨基丁酸）受体（正是它让一些青少年在家里不敢说出自己的真实成绩）。这些受体蛋白质会干扰神经元之间的连接，从而阻碍染色体提高年青动物的认知能力。

令人欣慰的是，荷尔蒙会减轻这种蛋白质的作用，从而让这些年青的动物回到更好的学习状态。这么说，荷尔蒙事实上会让青少年更加聪明哦！