在語(yǔ)言形成過(guò)程中，大腦會(huì)發(fā)出信號(hào),，可以觀察到能說(shuō)兩種語(yǔ)言的人,，與語(yǔ)言和認(rèn)知處理有關(guān)的大腦活動(dòng)可能會(huì)發(fā)生變化。
近日,，刊登在《美國(guó)科學(xué)院院刊》（PNAS）的研究報(bào)告指出,，與只能講一種語(yǔ)言的人相比,，能說(shuō)兩種語(yǔ)言的人的大腦皮層區(qū)域會(huì)產(chǎn)生功能性和結(jié)構(gòu)性變化，這可能來(lái)源于其對(duì)語(yǔ)言的加工和執(zhí)行,?？蒲腥藛T已經(jīng)確定了會(huì)講兩種語(yǔ)言可能帶來(lái)與語(yǔ)言和認(rèn)知處理有關(guān)的大腦活動(dòng)的變化。
正如玩戲法的人的大腦其與儲(chǔ)存和處理復(fù)雜視覺(jué)運(yùn)動(dòng)有關(guān)的區(qū)域可能會(huì)出結(jié)構(gòu)的變化一樣,，西北大學(xué)神經(jīng)系統(tǒng)研究所的Nina Kraus及其同事們推測(cè),，由實(shí)踐驅(qū)動(dòng)的聲音處理能力引起的大腦變化在能講兩種語(yǔ)言的人的大腦中或許是可識(shí)別的。為了尋找這類變化,，該實(shí)驗(yàn)小組征召了芝加哥的48名中學(xué)生,，其中大約一半人只講英語(yǔ)，而另一半既講英語(yǔ)又講西班牙語(yǔ),。
研究人員將這些志愿者進(jìn)行了分組,，每個(gè)組都有數(shù)量大致相同的男性和女性。當(dāng)他們看一部電影的時(shí)候,，研究人員使用電生理技術(shù)測(cè)量了每一名志愿者的大腦對(duì)于記錄一個(gè)合成語(yǔ)音音節(jié)的能力——這個(gè)音節(jié)既被單獨(dú)播放,，又放到了經(jīng)錄制的亂哄哄的人類語(yǔ)音背景中播放。研究結(jié)果顯示,，與只能說(shuō)一種語(yǔ)言的人相比,，能說(shuō)兩種語(yǔ)言的人表現(xiàn)出了增強(qiáng)這個(gè)音節(jié)基頻的相關(guān)大腦皮層活動(dòng)，特別是在這個(gè)聲音放在亂哄哄的語(yǔ)音背景中播放的時(shí)候,。研究者表示,，這些發(fā)現(xiàn)提示能說(shuō)兩種語(yǔ)言的人可能擁有維持選擇性注意力和增強(qiáng)聽(tīng)覺(jué)分類的能力。（生物谷Bioon.com）
doi:10.1073/pnas.1201575109
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Subcortical encoding of sound is enhanced in bilinguals and relates to executive function advantages
ennifer Krizman, Viorica Marian, Anthony Shook, Erika Skoe, and Nina Krausa
Bilingualism profoundly affects the brain, yielding functional and structural changes in cortical regions dedicated to language processing and executive function [Crinion J, et al. (2006) Science 312:1537–1540; Kim KHS, et al. (1997) Nature 388:171–174]. Comparatively, musical training, another type of sensory enrichment, translates to expertise in cognitive processing and refined biological processing of sound in both cortical and subcortical structures. Therefore, we asked whether bilingualism can also promote experience-dependent plasticity in subcortical auditory processing. We found that adolescent bilinguals, listening to the speech syllable [da], encoded the stimulus more robustly than age-matched monolinguals. Specifically, bilinguals showed enhanced encoding of the fundamental frequency, a feature known to underlie pitch perception and grouping of auditory objects. This enhancement was associated with executive function advantages. Thus, through experience-related tuning of attention, the bilingual auditory system becomes highly efficient in automatically processing sound. This study provides biological evidence for system-wide neural plasticity in auditory experts that facilitates a tight coupling of sensory and cognitive functions.
