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PNAS:早产的人类大脑就能区分出音节

一项研究发现,最早至足月前的3个月的时候,未成熟的人类大脑就建立了帮助解读人类语音的神经功能。

在出生的时候,儿童能够分辨某些音节并识别出人类语言,但是尚不清楚这些未成熟的神经回路是如何处理语音的。

Fabrice Wallois及其同事使用床边功能光学成像设备对12名28到32周孕期年龄的早产儿进行了扫描——这是能够记录下皮层对外部刺激做出响应的最早年龄——从而研究这些未成熟的早产大脑是否能够感受音节的语言和非语言差异。

这组作者发现了早产的和成年的语言处理的一些相似性,包括对从“ba”到“ga”音节的变化以及从男性到女性语音变化的神经响应。此外,尽管这些测试都引起了在胎儿发育期首先形成的右额区的响应,音节变化还引起了左半球的响应,这提示某些大脑语言区最早至足月前的3个月的时候就表现出了复杂的组织程度。

这些发现表明人类大脑在发育的过程中会及早地组织起来从而帮助解读语音。

了解更多:

Syllabic discrimination in premature human infants prior to complete formation of cortical layers

PNAS, February 25, 2013, | doi:10.1073/pnas.1212220110

The ontogeny of linguistic functions in the human brain remains elusive. Although some auditory capacities are described before term, whether and how such immature cortical circuits might process speech are unknown. Here we used functional optical imaging to evaluate the cerebral responses to syllables at the earliest age at which cortical responses to external stimuli can be recorded in humans (28- to 32-wk gestational age). At this age, the cortical organization in layers is not completed. Many neurons are still located in the subplate and in the process of migrating to their final location. Nevertheless, we observed several points of similarity with the adult linguistic network. First, whereas syllables elicited larger right than left responses, the posterior temporal region escaped this general pattern, showing faster and more sustained responses over the left than over the right hemisphere. Second, discrimination responses to a change of phoneme (ba vs. ga) and a change of human voice (male vs. female) were already present and involved inferior frontal areas, even in the youngest infants (29-wk gestational age). Third, whereas both types of changes elicited responses in the right frontal region, the left frontal region only reacted to a change of phoneme. These results demonstrate a sophisticated organization of perisylvian areas at the very onset of cortical circuitry, 3 mo before term. They emphasize the influence of innate factors on regions involved in linguistic processing and social communication in humans.

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