大腦原來(lái)自帶消音系統(tǒng)

導(dǎo)讀：聽(tīng)覺(jué)皮層是我們的大腦處理聲音的區(qū)域，然而令人感到好奇的是，我們對(duì)其他聲音十分敏感，卻往往忽略了自身發(fā)出的聲音。而這種能力，其實(shí)對(duì)于我們而言至關(guān)重要……

Youre walking down a quiet street and suddenly you hear some footsteps. Undoubtedly， it means that theres someone around. But have you ever wondered why it occurs to us that its someone elses footsteps， not ours？

According to a new study published in the journal Nature， this phenomenon results from a function in our brain to ignore the noises we make ourselves.

In order to explore how our brain does this， a group of scientists from New York University in the US carried out an experiment with mice at Duke University. In the experiment， researchers controlled the sounds a group of mice could hear， reported Science Daily.

During the first several days， the mice would hear the same sound each time they took a step. This was just like “running on a tiny piano with each key playing exactly the same note”， senior study author Richard Mooney， a professor of neurobiology at Duke University， told Live Science.

Scientists found that their auditory cortex—the area of the brain that processes sound—became active at first but decreased its response to the sound after two or three minutes when the mice became familiar with it.

“Its almost like they were wearing special headphones that could filter out the sound of their own movements，” David Schneider， an assistant professor at the Center for Neural Science at New York University， told HuffPost.

But once the sound changed， their auditory cortex became active again.

This suggests that the “sensory filter” in a mouses brain could help it detect new sounds or abnormal noise in the environment easily after tuning out familiar sounds， according to Science Daily.

“For mice， this is really important，” said Schneider. “They are prey animals， so they really need to be able to listen for a cat creeping up on them， even when theyre walking and making noise.”

As important as it is for mices survival， the ability to ignore movement-related noises is also useful for humans when it comes to complex tasks， such as playing an instrument.

According to Schneider， “The ability to ignore the expected consequences of our movement gives us the extra-cool ability to detect when weve got it wrong. So if I play the piano just right， I hear it， but my auditory cortex is pretty silent. But when I play it wrong， I get a much larger response.”

So， our brain could be telling us， “Hey， that didnt sound right， maybe I should move my fingers a little different next time，” Schneider told HuffPost.

你正走在一條安靜的街道上，突然，你聽(tīng)見(jiàn)了腳步聲。毫無(wú)疑問(wèn)，這表示有人在附近。但你可曾想過(guò)，為什么我們會(huì)認(rèn)為是別人的腳步聲，而不是自己的呢？

據(jù)發(fā)布于《自然》期刊的一項(xiàng)新研究表明，這一現(xiàn)象源于大腦的一項(xiàng)功能——忽略我們自身發(fā)出的聲音。

為了探索大腦是如何做到這一點(diǎn)的，來(lái)自美國(guó)紐約大學(xué)的一支科學(xué)家隊(duì)伍在杜克大學(xué)用老鼠做了一項(xiàng)實(shí)驗(yàn)。據(jù)每日科學(xué)網(wǎng)站報(bào)道，在實(shí)驗(yàn)中，研究人員對(duì)一組老鼠能聽(tīng)見(jiàn)的聲音進(jìn)行了控制。

在最初的幾天里，每當(dāng)老鼠活動(dòng)時(shí)都會(huì)聽(tīng)到同樣的聲音。這就像“在一架小鋼琴上面活動(dòng)，每個(gè)琴鍵發(fā)出的都是同樣的聲音”，資深研究作者、杜克大學(xué)神經(jīng)生物學(xué)教授理查德·穆尼在接受《生活科學(xué)》雜志采訪時(shí)表示。

科學(xué)家們發(fā)現(xiàn)，老鼠的聽(tīng)覺(jué)皮層——大腦處理聲音的區(qū)域——?jiǎng)傞_(kāi)始的時(shí)候十分活躍，但過(guò)了兩三分鐘，老鼠對(duì)聲音熟悉了之后，它們的聽(tīng)覺(jué)皮層對(duì)聲音的反應(yīng)便降低了。

“這就像它們戴上了特制的耳機(jī)，過(guò)濾掉了自己活動(dòng)的聲音?！奔~約大學(xué)神經(jīng)科學(xué)中心助理教授大衛(wèi)·施耐德在接受《赫芬頓郵報(bào)》采訪時(shí)表示。

但一旦聲音改變，老鼠的聽(tīng)覺(jué)皮層便再次活躍了起來(lái)。

據(jù)每日科學(xué)網(wǎng)站報(bào)道，這意味著老鼠大腦中的“感覺(jué)過(guò)濾器”在熟悉的聲音消失后，能幫助它們輕松地察覺(jué)環(huán)境中的新聲音和反常噪音。

“對(duì)于老鼠而言，這點(diǎn)至關(guān)重要?！笔┠偷卤硎尽！八鼈兪瞧渌麆?dòng)物的獵物，所以即便它們?cè)谛袆?dòng)并發(fā)出聲音的時(shí)候，也十分需要能夠在貓偷偷靠近時(shí)有所察覺(jué)?！?/p>

老鼠的這種生存能力對(duì)于人類(lèi)而言同樣重要，人們可以通過(guò)忽略自身行動(dòng)所產(chǎn)生的聲音來(lái)完成復(fù)雜的工作，比如彈奏樂(lè)器。

施耐德認(rèn)為：“忽略行動(dòng)所帶來(lái)的預(yù)期結(jié)果的這種能力，令我們發(fā)現(xiàn)錯(cuò)誤的能力也異常出色。因此，如果我在彈鋼琴時(shí)沒(méi)有出現(xiàn)失誤，我的聽(tīng)覺(jué)皮層是安靜的。但如果我彈錯(cuò)了，我的反應(yīng)就大多了。”

所以，大腦能夠告訴我們：“嘿，那聽(tīng)起來(lái)不太對(duì)，下一次或許要用略微不同的指法進(jìn)行彈奏。”施耐德在接受《赫芬頓郵報(bào)》采訪時(shí)如此表示。

Word Study

filter /'f?lt?（r）/ v. 過(guò)濾

n. 濾器;過(guò)濾器

prey /pre?/ n. 獵物;受害物

creep /kri?p/ v. 悄悄地緩慢行進(jìn);躡手躡腳地移動(dòng)

I crept up the stairs， trying not to wake my parents.