Ecole Normale Supérieure, INSERM U960 and Université Paris 6, Paris F-75005, France.
Hum Brain Mapp. 2013 May;34(5):1208-19. doi: 10.1002/hbm.21504. Epub 2012 Jan 30.
Post-lingual deafness induces a decline in the ability to process phonological sounds or evoke phonological representations. This decline is paralleled with abnormally high neural activity in the right posterior superior temporal gyrus/supramarginal gyrus (PSTG/SMG). As this neural plasticity negatively relates to cochlear implantation (CI) success, it appears important to understand its determinants. We addressed the neuro-functional mechanisms underlying this maladaptive phenomenon using behavioral and functional magnetic resonance imaging (fMRI) data acquired in 10 normal-hearing subjects and 10 post-lingual deaf candidates for CI. We compared two memory tasks where subjects had to evoke phonological (speech) and environmental sound representations from visually presented items. We observed dissociations in the dynamics of right versus left PSTG/SMG neural responses as a function of duration of deafness. Responses in the left PSTG/SMG to phonological processing and responses in the right PSTG/SMG to environmental sound imagery both declined. However, abnormally high neural activity was observed in response to phonological visual items in the right PSTG/SMG, i.e., contralateral to the zone where phonological activity decreased. In contrast, no such responses (overactivation) were observed in the left PSTG/SMG in response to environmental sounds. This asymmetry in functional adaptation to deafness suggests that maladaptive reorganization of the right PSTG/SMG region is not due to balanced hemispheric interaction, but to a specific take-over of the right PSTG/SMG region by phonological processing, presumably because speech remains behaviorally more relevant to communication than the processing of environmental sounds. These results demonstrate that cognitive long-term alteration of auditory processing shapes functional cerebral reorganization.
后天性耳聋会导致处理语音声音或唤起语音表象的能力下降。这种下降与右后上颞叶/缘上回（PSTG/SMG）的异常高神经活动相平行。由于这种神经可塑性与人工耳蜗植入（CI）的成功呈负相关，因此了解其决定因素似乎很重要。我们使用从 10 名正常听力受试者和 10 名后天性耳聋人工耳蜗植入候选者中获得的行为和功能磁共振成像（fMRI）数据，研究了这种适应性不良现象的神经功能机制。我们比较了两项记忆任务，在这些任务中，受试者必须从视觉呈现的项目中唤起语音（言语）和环境声音的表象。我们观察到，右与左 PSTG/SMG 神经反应的动力学随耳聋时间的不同而分离。对语音处理的左 PSTG/SMG 反应和对环境声音意象的右 PSTG/SMG 反应都下降了。然而，在右 PSTG/SMG 中，对语音视觉项目的反应却出现了异常高的神经活动，即与语音活动减少的区域相对应。相比之下，在左 PSTG/SMG 中，对环境声音的反应没有观察到这种过度兴奋（过度激活）。这种对耳聋的功能适应的不对称性表明，右 PSTG/SMG 区域的适应性重组不是由于半球间的平衡相互作用，而是由于语音处理对右 PSTG/SMG 区域的特定接管，可能是因为言语在行为上比环境声音的处理更与交流相关。这些结果表明，听觉处理的认知长期改变塑造了功能大脑重组。
