科研人員報告說,，大腦的人臉視覺處理系統(tǒng)在生命早期的一個增強了的神經(jīng)可塑性時期進行了微調(diào)。此前的研究提示這樣一個時期在生命的頭幾個月存在,，但是究竟神經(jīng)回路是新建立的還是僅僅在這個時期進行了調(diào)整還不清楚。為了回答這個問題,，Brigitte Röder及其同事研究了出生失明,、至多14年后視力恢復(fù)的11個人，并且研究了匹配的健康受試者以及有部分視力的受試者,。在一次持續(xù)的腦電圖檢測中,，這組作者記錄下了受試者對人臉及房屋的完整的和混亂的照片做出響應(yīng)的事件相關(guān)性電位。該研究表明盡管所有的受試者都可以識別這些照片,，但是無論有沒有向曾在出生時失明的人展示人臉或房屋的照片,，他們都會出現(xiàn)一個被稱為N170的電位——它通常是在對人臉做出響應(yīng)的時候才出現(xiàn)的。相比之下,，健康人和有部分視力的受試者僅僅在對人臉做出響應(yīng)的時候才出現(xiàn)了N170電位,。這組作者說，這些發(fā)現(xiàn)揭示出了人類出生就擁有面部處理系統(tǒng)的基本神經(jīng)回路,，但是大腦依賴于生命早期的視覺經(jīng)驗微調(diào)這些神經(jīng)回路,，從而增強對視覺的處理。（生物谷 Bioon.com）
生物谷推薦的英文摘要
PNAS doi: 10.1073/pnas.1309963110
Sensitive periods for the functional specialization of the neural system for human face processing
Brigitte Rödera,1, Pia Leya, Bhamy H. Shenoyb, Ramesh Kekunnayab, and Davide Bottari
The aim of the study was to identify possible sensitive phases in the development of the processing system for human faces. We tested the neural processing of faces in 11 humans who had been blind from birth and had undergone cataract surgery between 2 mo and 14 y of age. Pictures of faces and houses, scrambled versions of these pictures, and pictures of butterflies were presented while event-related potentials were recorded. Participants had to respond to the pictures of butterflies (targets) only. All participants, even those who had been blind from birth for several years, were able to categorize the pictures and to detect the targets. In healthy controls and in a group of visually impaired individuals with a history of developmental or incomplete congenital cataracts, the well-known enhancement of the N170 (negative peak around 170 ms) event-related potential to faces emerged, but a face-sensitive response was not observed in humans with a history of congenital dense cataracts. By contrast, this group showed a similar N170 response to all visual stimuli, which was indistinguishable from the N170 response to faces in the controls. The face-sensitive N170 response has been associated with the structural encoding of faces. Therefore, these data provide evidence for the hypothesis that the functional differentiation of category-specific neural representations in humans, presumably involving the elaboration of inhibitory circuits, is dependent on experience and linked to a sensitive period. Such functional specialization of neural systems seems necessary to archive high processing proficiency.
