Rest Assured: The Brain Practices the Day's Lessons as We Sleep

Are you sleeping well these days? You know, it's still amazing to me that experts haven't reached a consensus on what the exact purpose of sleep is.

One possibility is that it helps us build memory and problem solve.

In 1994 neuroscientists at the University of Arizona recorded the brain activity of rats as they navigated mazes and noted that specific brain cells (called "place cells") fired at specific spots along the route.

Then as the rats slumbered that night, scientists found the same cells firing, in the same order. The rat's brains were practicing running through the maze as they slept!

Researchers believe that the brain reactivates patterns of neural connections it made during the day—thus strengthening long-term memory during the night.

A 2005 fMRI study of pianists learning a complicated score found that they engaged different brain areas for the task, and that they performed better, only after snoozing.

During sleep, memory was specifically strengthened in the optimal brain areas for that task—those known to control hand movements. And these were different from the areas activated during the initial learning of the sequence.

Read about these and other sleep studies in the August/September issue of Scientific American MIND. Then, sleep on it.

保证睡眠：当我们睡觉的时候，大脑仍然在处理我们白天所学的知识。

你这几天睡得还好吗？你可能知道，专家们目前对睡眠的确切目的还不能达成一致意见，对这一点我仍然感到奇怪。

 其中一种可能性就是睡眠帮助我们强化记忆和解决问题。

在1994年亚利桑那大学的神经科学家们做了个实验，他们纪录了老鼠闯迷宫时的脑活动。科学家们发现老鼠的一些特定脑细胞（叫做“位置细胞”）在老鼠处于迷宫途中的特定地点时表现活跃。

当晚这些老鼠睡觉的时候，科学家们发现这些相同的脑细胞表现出相同程度的活跃。老鼠的大脑在它们睡觉的时候还在锻炼闯迷宫呢！

研究人员认为大脑把白天形成的神经联系重新激活——也就是说在晚上长期记忆得到了加强。

研究人员在2005年对学习一篇复杂乐谱的钢琴家们进行了功能性核磁共振成像（Functional Magetic Resonance Imaging, fMRI）研究，结果表明，不同大脑区域参与到乐谱学习之中；研究同时发现只有在钢琴家们得到睡眠之后他们才演奏得更好。

 在睡眠的时候，记忆特别在负责记忆任务的最佳大脑区域得到加强---那些控制手活动的区域。这些区域不同于刚开始学习序列时候那些被激活的区域。

《科学美国人》的8-9月“心理”栏目有更多关于睡眠的研究，你可以进一步阅读了解。读完之后，睡个好觉吧！

Vocabulary:
Consensus: 一致
Neuroscientist: 神经科学家
Navigate: 航行；领航
Maze: 迷宫
Fire: 兴奋
Slumber:  睡眠
Score: 乐谱
Snooze: 小睡；打盹儿
Sequence: 序列