Training of ultra-fast speech comprehension induces functional reorganization of the central-visual system in late-blind humans
Training of ultra-fast speech comprehension induces functional reorganization of the central-visual system in late-blind humans
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DOI：
10.3389/fnhum.2013.00701
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发表时间：
2013-10-23
影响因子：
2.9
通讯作者：
Ackermann, Hermann
中科院分区：
文献类型：
--
作者：
Dietrich, Susanne;Hertrich, Ingo;Ackermann, Hermann
患有外周来源视力丧失的人可能会以每秒约22个音节(Syl)的速度学习理解口语(S)--远远超过未经训练的听者的最高表现水平(约8 Syl/S)。以前的发现表明，中央视觉系统对盲人受试者加速语音的处理起到了作用。作为延伸，本培训研究解决了获得超快(18Syl/S)言语感知技能是否会导致晚期失明参与者重新激活中枢-视觉血流动力学的问题。此外，我们还询问了视力正常或残留的受试者通过特定的训练措施可以在多大程度上提高对加速言语的理解。为此，在大约6个月的训练前后，受试者在听中快音率和超快音率(8或18 Syl/S)的正反向句子时进行了功能磁共振成像(FMRI)。六名参与者中有四名表现出超快语音感知的显著增强(约70%正确重复单词)，而其余两名参与者的行为表现没有改变。只有视力非常低的受试者才表现出训练诱导的中央视觉系统的血流动力学激活。相比之下，视力中度受损甚至正常的参与者在训练后表现出右半球额叶或双侧前颞叶反应的增加。所有训练效果显著的受试者都表现出左半球SMA血流动力学激活的伴随增加。尽管行为表现相似，但受过训练的“专家”似乎使用了不同的超高速语音处理策略，这取决于枕叶皮质是否仍用于视觉处理。
Individuals suffering from vision loss of a peripheral origin may learn to understand spoken language at a rate of up to about 22 syllables (syl) per seconds (s)-exceeding by far the maximum performance level of untrained listeners (ca. 8 syl/s). Previous findings indicate the central-visual system to contribute to the processing of accelerated speech in blind subjects. As an extension, the present training study addresses the issue whether acquisition of ultra-fast (18 syl/s) speech perception skills induces de novo central-visual hemodynamic activation in late-blind participants. Furthermore, we asked to what extent subjects with normal or residual vision can improve understanding of accelerated verbal utterances by means of specific training measures. To these ends, functional magnetic resonance imaging (fMRI) was performed while subjects were listening to forward and reversed sentence utterances of moderately fast and ultra-fast syllable rates (8 or 18 syl/s) prior to and after a training period of ca. 6 months. Four of six participants showed-independently from residual visual functions-considerable enhancement of ultra-fast speech perception (about 70% points correctly repeated words) whereas behavioral performance did not change in the two remaining participants. Only subjects with very low visual acuity displayed training-induced hemodynamic activation of the central-visual system. By contrast, participants with moderately impaired or even normal visual acuity showed, instead, increased right-hemispheric frontal or bilateral anterior temporal lobe responses after training. All subjects with significant training effects displayed a concomitant increase of hemodynamic activation of left-hemispheric SMA. In spite of similar behavioral performance, trained "experts" appear to use distinct strategies of ultra-fast speech processing depending on whether the occipital cortex is still deployed for visual processing.