Adaptive changes in early and late blind: A fMRI study of verb generation to heard nouns
Adaptive changes in early and late blind: A fMRI study of verb generation to heard nouns
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DOI：
10.1152/jn.00129.2002
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发表时间：
2002-12-01
影响因子：
2.5
通讯作者：
Raichle, ME
中科院分区：
文献类型：
--
作者：
Burton, H;Snyder, AZ;Raichle, ME
盲人识字需要学习盲文。沿着其他人，我们已经证明阅读盲文激活视觉皮层。这包括纹状体皮质（VI），即，距状沟的两侧，以及舌、梭状、楔、枕外侧、颞下回和颞中回的几个高级视觉区。视觉皮层中磁共振（MR）信号的空间范围和幅度对于那些早年失明的人来说是最大的。成年后失去视力的人，后来学习盲文，仍然在一些相同的视觉皮层区域表现出活动，特别是VI。这些发现表明，这些视觉皮层区域变得适应处理触觉信息，这种跨模态神经变化可能支持盲文识字。在这里，我们测试的备择假设，这些地区直接响应语言方面的任务。因此，盲人的语言任务执行应该激活相同的视觉皮层区域，无论输入方式。具体来说，盲人的视觉皮层活动应该在涉及听到的单词的语言任务中出现。八个早期失明，六个晚期失明，八个正常人使用功能性磁共振成像（fMRI）进行了研究。控制任务是被动听难以辨认的声音（反向词）匹配的名词在声音强度，持续时间和频谱内容。在个体受试者水平上使用基于一般线性模型的方法分析功能反应，在组水平上使用基于体素的ANOVA和t检验分析。盲人和视力正常的受试者在左下额叶、背外侧前额叶和左后上级颞回的语言区的激活情况相当。主要的区别是双侧的，左优势激活相同的视觉皮层区域以前指出与盲文阅读在所有盲人受试者。在早期失明的个体中，左侧的空间范围和反应幅度最大。在晚盲组的反应主要局限于第VI和附近部分的舌和梭状回。这些结果证实了盲人视觉皮层中存在适应性，但反对盲文阅读过程中这种活动代表体感（触觉）处理的观点。相反，我们认为，这些反应可以最简约的语言操作方面的解释。这些反应仍然可能代表最初用于处理声音或触摸的适应，但随后在盲文阅读技能的获得期间推广到其他模态。
Literacy for blind people requires learning Braille. Along with others, we have shown that reading Braille activates visual cortex. This includes striate cortex (VI), i.e., banks of calcarine sulcus, and several higher visual areas in lingual, fusiform, cuneus, lateral occipital, inferior temporal, and middle temporal gyri. The spatial extent and magnitude of magnetic resonance (MR) signals in visual cortex is greatest for those who became blind early in life. Individuals who lost sight as adults, and subsequently learned Braille, still exhibited activity in some of the same visual cortex regions, especially VI. These findings suggest these visual cortex regions become adapted to processing tactile information and that this cross-modal neural change might support Braille literacy. Here we tested the alternative hypothesis that these regions directly respond to linguistic aspects of a task. Accordingly, language task performance by blind persons should activate the same visual cortex regions regardless of input modality. Specifically, visual cortex activity in blind people ought to arise during a language task involving heard words. Eight early blind, six late blind, and eight sighted subjects were studied using functional magnetic resonance imaging (fMRI) during covert generation of verbs to heard nouns. The control task was passive listening to indecipherable sounds (reverse words) matched to the nouns in sound intensity, duration, and spectral content. Functional responses were analyzed at the level of individual subjects using methods based on the general linear model and at the group level, using voxel based ANOVA and t-test analyses. Blind and sighted subjects showed comparable activation of language areas in left inferior frontal, dorsolateral prefrontal, and left posterior superior temporal gyri. The main distinction was bilateral, left dominant activation of the same visual cortex regions previously noted with Braille reading in all blind subjects. The spatial extent and magnitude of responses was greatest on the left in early blind individuals. Responses in the late blind group mostly were confined to V I and nearby portions of the lingual and fusiform gyri. These results confirm the presence of adaptations in visual cortex of blind people but argue against the notion that this activity during Braille reading represents somatosensory (haptic) processing. Rather, we suggest that these responses can be most parsimoniously explained in terms of linguistic operations. It remains possible that these responses represent adaptations which initially are for processing either sound or touch, but which are later generalized to the other modality during acquisition of Braille reading skills.