Zhou Xiao-Qing, Zhang Qing-Ling, Xi Xin, Leng Ming-Rong, Liu Hao, Liu Shu, Zhang Ting, Yuan Wei
Department of Otolaryngology, Chongqing Medical University, Chongqing, China.
Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing, China.
Front Neurosci. 2023 Jun 2;17:1126813. doi: 10.3389/fnins.2023.1126813. eCollection 2023.
Cochlear implantation is currently the most successful intervention for severe-to-profound sensorineural hearing loss, particularly in deaf infants and children. Nonetheless, there remains a significant degree of variability in the outcomes of CI post-implantation. The purpose of this study was to understand the cortical correlates of the variability in speech outcomes with a cochlear implant in pre-lingually deaf children using functional near-infrared spectroscopy (fNIRS), an emerging brain-imaging technique.
In this experiment, cortical activities when processing visual speech and two levels of auditory speech, including auditory speech in quiet and in noise with signal-to-noise ratios of 10 dB, were examined in 38 CI recipients with pre-lingual deafness and 36 normally hearing children whose age and sex matched CI users. The HOPE corpus (a corpus of Mandarin sentences) was used to generate speech stimuli. The regions of interest (ROIs) for the fNIRS measurements were fronto-temporal-parietal networks involved in language processing, including bilateral superior temporal gyrus, left inferior frontal gyrus, and bilateral inferior parietal lobes.
The fNIRS results confirmed and extended findings previously reported in the neuroimaging literature. Firstly, cortical responses of superior temporal gyrus to both auditory and visual speech in CI users were directly correlated to auditory speech perception scores, with the strongest positive association between the levels of cross-modal reorganization and CI outcome. Secondly, compared to NH controls, CI users, particularly those with good speech perception, showed larger cortical activation in the left inferior frontal gyrus in response to all speech stimuli used in the experiment.
In conclusion, cross-modal activation to visual speech in the auditory cortex of pre-lingually deaf CI children may be at least one of the neural bases of highly variable CI performance due to its beneficial effects for speech understanding, thus supporting the prediction and assessment of CI outcomes in clinic. Additionally, cortical activation of the left inferior frontal gyrus may be a cortical marker for effortful listening.
人工耳蜗植入是目前治疗重度至极重度感音神经性听力损失最成功的干预手段，尤其是对于失聪婴幼儿和儿童。尽管如此，人工耳蜗植入术后的效果仍存在很大程度的差异。本研究的目的是使用功能近红外光谱技术（fNIRS）这一新兴的脑成像技术，了解语前聋儿童人工耳蜗植入后言语结果差异的皮层相关性。
在本实验中，对38名语前聋人工耳蜗植入者和36名年龄和性别与人工耳蜗使用者匹配的听力正常儿童进行了研究，检测他们在处理视觉言语以及两种水平的听觉言语（包括安静环境下的听觉言语和信噪比为10 dB的噪声环境下的听觉言语）时的皮层活动。使用HOPE语料库（一个汉语句子语料库）生成言语刺激。fNIRS测量的感兴趣区域（ROI）是参与语言处理的额颞顶网络，包括双侧颞上回、左侧额下回和双侧顶下小叶。
fNIRS结果证实并扩展了先前神经影像学文献中报道的研究结果。首先，人工耳蜗使用者颞上回对听觉和视觉言语的皮层反应与听觉言语感知分数直接相关，跨模态重组水平与人工耳蜗植入效果之间的正相关最强。其次，与听力正常的对照组相比，人工耳蜗使用者，尤其是那些言语感知良好的使用者，在对实验中使用的所有言语刺激做出反应时，左侧额下回的皮层激活更大。
总之，语前聋人工耳蜗植入儿童听觉皮层对视觉言语的跨模态激活可能至少是人工耳蜗植入效果高度可变的神经基础之一，因为它对言语理解有有益影响，从而支持临床中人工耳蜗植入效果的预测和评估。此外，左侧额下回的皮层激活可能是努力聆听的皮层标志。
