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.

保證睡眠：當(dāng)我們睡覺的時(shí)候，大腦仍然在處理我們白天所學(xué)的知識(shí)。

你這幾天睡得還好嗎？你可能知道，專家們目前對(duì)睡眠的確切目的還不能達(dá)成一致意見，對(duì)這一點(diǎn)我仍然感到奇怪。

 其中一種可能性就是睡眠幫助我們強(qiáng)化記憶和解決問題。

在1994年亞利桑那大學(xué)的神經(jīng)科學(xué)家們做了個(gè)實(shí)驗(yàn)，他們紀(jì)錄了老鼠闖迷宮時(shí)的腦活動(dòng)。科學(xué)家們發(fā)現(xiàn)老鼠的一些特定腦細(xì)胞（叫做“位置細(xì)胞”）在老鼠處于迷宮途中的特定地點(diǎn)時(shí)表現(xiàn)活躍。

當(dāng)晚這些老鼠睡覺的時(shí)候，科學(xué)家們發(fā)現(xiàn)這些相同的腦細(xì)胞表現(xiàn)出相同程度的活躍。老鼠的大腦在它們睡覺的時(shí)候還在鍛煉闖迷宮呢！

研究人員認(rèn)為大腦把白天形成的神經(jīng)聯(lián)系重新激活——也就是說在晚上長(zhǎng)期記憶得到了加強(qiáng)。

研究人員在2005年對(duì)學(xué)習(xí)一篇復(fù)雜樂譜的鋼琴家們進(jìn)行了功能性核磁共振成像（Functional Magetic Resonance Imaging, fMRI）研究，結(jié)果表明，不同大腦區(qū)域參與到樂譜學(xué)習(xí)之中；研究同時(shí)發(fā)現(xiàn)只有在鋼琴家們得到睡眠之后他們才演奏得更好。

 在睡眠的時(shí)候，記憶特別在負(fù)責(zé)記憶任務(wù)的最佳大腦區(qū)域得到加強(qiáng)---那些控制手活動(dòng)的區(qū)域。這些區(qū)域不同于剛開始學(xué)習(xí)序列時(shí)候那些被激活的區(qū)域。

《科學(xué)美國(guó)人》的8-9月“心理”欄目有更多關(guān)于睡眠的研究，你可以進(jìn)一步閱讀了解。讀完之后，睡個(gè)好覺吧！

Vocabulary:
Consensus: 一致
Neuroscientist: 神經(jīng)科學(xué)家
Navigate: 航行；領(lǐng)航
Maze: 迷宮
Fire: 興奮
Slumber:  睡眠
Score: 樂譜
Snooze: 小睡；打盹兒
Sequence: 序列