Twomey Tae, Waters Dafydd, Price Cathy J, Evans Samuel, MacSweeney Mairéad
ESRC Deafness, Cognition and Language Research Centre, University College London, WC1H 0PD, United Kingdom.
Institute of Cognitive Neuroscience, University College London, WC1N 3AR, United Kingdom.
J Neurosci. 2017 Sep 27;37(39):9564-9573. doi: 10.1523/JNEUROSCI.0846-17.2017. Epub 2017 Aug 18.
To investigate how hearing status, sign language experience, and task demands influence functional responses in the human superior temporal cortices (STC) we collected fMRI data from deaf and hearing participants (male and female), who either acquired sign language early or late in life. Our stimuli in all tasks were pictures of objects. We varied the linguistic and visuospatial processing demands in three different tasks that involved decisions about (1) the sublexical (phonological) structure of the British Sign Language (BSL) signs for the objects, (2) the semantic category of the objects, and (3) the physical features of the objects.Neuroimaging data revealed that in participants who were deaf from birth, STC showed increased activation during visual processing tasks. Importantly, this differed across hemispheres. Right STC was consistently activated regardless of the task whereas left STC was sensitive to task demands. Significant activation was detected in the left STC only for the BSL phonological task. This task, we argue, placed greater demands on visuospatial processing than the other two tasks. In hearing signers, enhanced activation was absent in both left and right STC during all three tasks. Lateralization analyses demonstrated that the effect of deafness was more task-dependent in the left than the right STC whereas it was more task-independent in the right than the left STC. These findings indicate how the absence of auditory input from birth leads to dissociable and altered functions of left and right STC in deaf participants. Those born deaf can offer unique insights into neuroplasticity, in particular in regions of superior temporal cortex (STC) that primarily respond to auditory input in hearing people. Here we demonstrate that in those deaf from birth the left and the right STC have altered and dissociable functions. The right STC was activated regardless of demands on visual processing. In contrast, the left STC was sensitive to the demands of visuospatial processing. Furthermore, hearing signers, with the same sign language experience as the deaf participants, did not activate the STCs. Our data advance current understanding of neural plasticity by determining the differential effects that hearing status and task demands can have on left and right STC function.
为了研究听力状况、手语经验和任务要求如何影响人类颞上叶皮质（STC）的功能反应，我们收集了聋人和听力正常参与者（男性和女性）的功能磁共振成像（fMRI）数据，这些参与者在生命早期或晚期习得手语。我们在所有任务中的刺激物都是物体的图片。我们在三个不同任务中改变了语言和视觉空间处理要求，这些任务涉及对（1）物体的英国手语（BSL）手语的次词汇（语音）结构、（2）物体的语义类别和（3）物体的物理特征做出决策。神经成像数据显示，在先天性耳聋的参与者中，STC在视觉处理任务期间显示出激活增加。重要的是，这种情况在不同半球有所不同。无论任务如何，右侧STC始终被激活，而左侧STC对任务要求敏感。仅在BSL语音任务中，左侧STC检测到显著激活。我们认为，该任务对视觉空间处理提出了比其他两个任务更高的要求。在有听力的手语使用者中，在所有三个任务期间，左右侧STC均未出现增强激活。侧化分析表明，耳聋的影响在左侧STC比右侧STC更依赖任务，而在右侧STC比左侧STC更不依赖任务。这些发现表明，先天性缺乏听觉输入如何导致聋人参与者左右侧STC功能的分离和改变。那些先天性耳聋的人可以为神经可塑性提供独特的见解，特别是在主要对听力正常者的听觉输入做出反应的颞上叶皮质（STC）区域。在这里，我们证明，在那些先天性耳聋的人中，左右侧STC具有改变的和可分离的功能。无论对视觉处理的要求如何，右侧STC都会被激活。相比之下，左侧STC对视觉空间处理的要求敏感。此外，与聋人参与者有相同手语经验的有听力的手语使用者并未激活STC。我们的数据通过确定听力状况和任务要求对左右侧STC功能可能产生的不同影响，推进了当前对神经可塑性的理解。
