加拿大蒙特利爾大學(xué)科學(xué)家發(fā)現(xiàn),，大腦具有驚人的可塑性,，正常情況下與眼睛相連的視覺信息處理與空間感知腦區(qū),，也能與聲音信息形成重新連接,，因此一些先天性失明的盲人能通過聲音來感知空間,，實(shí)現(xiàn)以耳代目。該研究發(fā)表在3月15日的美國(guó)《國(guó)家科學(xué)院院刊》（PNAS）上,。
蒙特利爾大學(xué)圣-賈斯汀醫(yī)學(xué)研究中心奧利弗·柯利根和神經(jīng)心理學(xué)與認(rèn)知研究中心的弗朗哥·萊普合作,，對(duì)11位先天失明者和11位正常人進(jìn)行了比較研究。研究人員在給他們聽不同聲音的同時(shí),，用核磁共振成像（MRI）掃描他們的腦部活動(dòng),。此前的一些研究也顯示，盲人在將聲音處理作為空間感知方面的能力比正常人要強(qiáng),?？吕忉屨f：“之前的研究表明，先天失明的人腦部枕區(qū)與非視覺信息處理過程有關(guān),。而我們最近的研究表明,，盲人的腦部枕區(qū)在與聲音信息處理系統(tǒng)重新連接之后，其視覺皮層還保留著像正常人那樣的功能組織,。視覺皮層中右背側(cè)枕流區(qū)的某些地方能將原有大腦神經(jīng)網(wǎng)絡(luò)的功能重新組合,，以處理空間信息。”視覺皮層位于大腦后部,，左右半球各有一個(gè),，稱為枕葉，負(fù)責(zé)處理視覺畫面,。
柯利根認(rèn)為,，這證明大腦具有驚人的可塑性，而可塑性是指大腦由于閱歷經(jīng)驗(yàn)變化而發(fā)生變化的能力,。大腦中有專門的腦區(qū)用于空間處理,，即使一個(gè)人剛出生就失明，他的大腦也非常靈活,，可以讓神經(jīng)元周圍的微環(huán)境發(fā)展變化,，使神經(jīng)元擁有并執(zhí)行一些新功能。
對(duì)于先天失明嬰兒的大腦如何發(fā)育出這種重新連接,，柯利根解釋說,，在早期生命中，大腦在經(jīng)驗(yàn)感受的基礎(chǔ)上塑造著自身,，某些突觸連接消失了,，而另一些會(huì)得到加強(qiáng),，突觸連接使神經(jīng)元得以互相交流,。“在嬰兒8個(gè)月左右,，大腦發(fā)育高峰結(jié)束，此后大約40%的視覺皮層突觸開始逐漸移除,，到11歲左右突觸密度達(dá)到穩(wěn)定,。重新連接的發(fā)生，可能是作為不斷變化的神經(jīng)連接維護(hù)機(jī)制的一部分,，但這一理論還需要進(jìn)一步檢驗(yàn),。”（生物谷Bioon.com）
生物谷推薦原文出處：
PNAS doi: 10.1073/pnas.1013928108
Functional specialization for auditory–spatial processing in the occipital cortex of congenitally blind humans
Olivier Collignona,b,1, Gilles Vandewallec, Patrice Vossa, Geneviève Albouyc, Geneviève Charbonneaua, Maryse Lassondea,b, and Franco Leporea
Abstract
The study of the congenitally blind (CB) represents a unique opportunity to explore experience-dependant plasticity in a sensory region deprived of its natural inputs since birth. Although several studies have shown occipital regions of CB to be involved in nonvisual processing, whether the functional organization of the visual cortex observed in sighted individuals (SI) is maintained in the rewired occipital regions of the blind has only been recently investigated. In the present functional MRI study, we compared the brain activity of CB and SI processing either the spatial or the pitch properties of sounds carrying information in both domains (i.e., the same sounds were used in both tasks), using an adaptive procedure specifically designed to adjust for performance level. In addition to showing a substantial recruitment of the occipital cortex for sound processing in CB, we also demonstrate that auditory–spatial processing mainly recruits the right cuneus and the right middle occipital gyrus, two regions of the dorsal occipital stream known to be involved in visuospatial/motion processing in SI. Moreover, functional connectivity analyses revealed that these reorganized occipital regions are part of an extensive brain network including regions known to underlie audiovisual spatial abilities (i.e., intraparietal sulcus, superior frontal gyrus). We conclude that some regions of the right dorsal occipital stream do not require visual experience to develop a specialization for the processing of spatial information and to be functionally integrated in a preexisting brain network dedicated to this ability.
