Young brains can forget painful memories, but old ones tend not to. An animal study in the journal Science finds that it may be possible to restore the old brain to its younger, more pliable state.

对于过去痛苦的记忆，年轻的大脑能忘记它们，但是年老的大脑则没有那么容易了。发表在《科学》(Science)杂志上的一项动物研究发现，让大脑“返老还童，恢复其“韧性”或许是可行的。

Freeing the Mind to Forget

Some things are hard to remember. Others are hard to forget―especially things that are traumatic. But kids, it turns out, are better than adults at forgetting the bad stuff. Now scientists think they know why. According to an animal study in the September 4th issue of the journal Science, the brains of adults erect physical barriers that keep painful memories intact.

As adults, events that emotionally disturb us tend to get seared into our brains. And those memories can resurface, causing anxiety, fear and even post-traumatic stress disorder. But young brains are much more resilient―and can even erase unpleasant memories.

To get a better handle on this youthful forgetting, scientists studied the brains of young and old rats. They found that in adult brains, a physical net forms around certain cells in the amygdala, a structure associated with emotional memories. Adults that had been trained to associate a mild foot shock with a specific sound would flinch when they just heard the sound. But using a drug to dissolve this barrier restored the older rats’ ability to extinguish fearful memories. So rats that got the net-busting treatment stayed calm when they heard the sound.

One of the few instances where a net loss is a real gain.

释放心灵，忘记不快

有些事情很难记住。有些事情――尤其是那些带来巨大创伤的事情――则很难忘记。不过，有结果发现在忘记糟糕事情方面，小孩子要比成年人做得更好。现在科学家们认为他们找到了答案。根据发表在9月4日《科学》(Science)杂志上的一项动物研究结果，成年人的大脑会竖立起有形的障碍，使得过去痛苦的记忆保持原封不动。

对于成年人，那些在情感上扰乱我们的事情易于深深印在我们的大脑内。而且那些记忆能重现出来，从而导致我们焦虑、害怕甚至让我们患上创伤后精神紧张性障碍(post-traumatic stress disorder)。但是年轻大脑的“柔韧性”要好的多---它们甚至能抹去那些不快的记忆。

科学家们为了更好的理解这种“年轻的遗忘”现象，他们研究了年轻和年老老鼠的大脑。科学家们发现，在成年老鼠大脑的杏仁核(杏仁核与情感记忆有关)的某些细胞周围形成了一种有形的网。科学家对成年老鼠进行了训练，使得这些老鼠能把轻微的足部电击和一种特定的声音联系在一起，一旦这些老鼠听到这种声音，它们就会退缩。但是当使用一种药物去掉这种障碍后，这些成年老鼠又恢复了它们消除可怕记忆的能力。因此对老鼠进行“消除障碍网”处理后，当这些老鼠在听到这种特定声音的时候，它们仍然保持安静的状态。

这是完全失去变为真正获得的为数不多的例子之一。

Vocabulary：

Restore：恢复

Pliable：易弯曲的；柔韧的；易受影响的

Traumatic：创伤的

Erect：建立；竖立

Intact：不动的

Disturb：干扰

Sear：烧灼；使骤然感到剧痛

Post-traumatic stress disorder：创伤后精神紧张性障碍(简称PTSD)

Resilient：有适应力的

Erase：擦去

Amygdala：杏仁核；扁桃体

Flinch：(突然)退缩

Dissolve：消除；(使)消失、消散

Extinguish：扑灭；毁灭

注释：

文章最后的Net loss使用了一语双关。Net 有“网“的意思，指文章中“有形的障碍网”，另外，net 还有“静得的，纯的”意思。Net loss：既可表示“有形的障碍网”的失去，也表示“完全的失去”。