耳蜗术后患儿声源定位训练的作用及其中枢机制

Patients with cochlear implants (CI) have sound source localization disorder and poor speech recognition ability under noise. Sound source localization ability is an important part of the listening function and one of the key factors in speech recognition. Our previous research based on event-related potential (ERP) technology found that the sound source localization training can specifically induce central plasticity changes and establish effective network connections in the brain, which can be used as a means of improving the sound source localization of patients with hearing impairment. However, there are few reports on the effectiveness and central mechanism of sound source localization training for patients after CI. On the other hand, our study found that there is a process of development and remodeling of the auditory center in children after CI. Now, this project intends to combine behavior and event-related potential (ERP) technology, and take children with unilateral or bilateral CI and normal children as subjects to investigate the following questions :(1) whether the neural mechanism of sound localization of children with CI is different from that of normal hearing children?(2) can sound localization training improve the ability of sound localization and its neural mechanism?(3) can sound source localization training improve speech recognition ability under noise and its neural mechanism? This project will make use of the advantages of interdisciplinary study to deeply understand the neural mechanism of human sound source localization, and the research results will be helpful to further improve the rehabilitation of CI patients.

人工耳蜗（CI）植入患者存在声源定位障碍及噪声下言语识别能力下降。声源定位能力是听功能的重要组成部分，也是言语识别的关键因素之一。我们前期基于事件相关电位（ERP）技术研究发现，通过声源定位训练可针对性诱导中枢可塑性改变，建立脑区间有效网络连接，可作为改善听力损伤患者声源定位的康复手段。但CI术后患者的声源定位训练的有效性及中枢机制方面研究报道甚少。另一方面，我们研究发现CI术后患儿存在听觉中枢的发育及重塑过程。本项目拟结合行为和ERP技术，以单、双侧CI植入患儿及正常儿童作为被试，考察如下问题：（1）CI术后患儿的声源定位中枢处理机制是否与正常儿童存在差异？（2）声源定位训练是否可以改善声源定位能力及其中枢机制？（3）声源定位训练是否可以提高噪声下言语识别能力及其中枢机制？本项目将利用交叉学科的优势，深入了解人类声源定位的中枢处理机制，且研究成果有助于进一步提高CI术后患者的康复效果。

本项目拟结合行为学和功能性近红外脑成像技术，以单、双侧CI植入患儿及正常儿童作为被试，研究语前聋人工耳蜗植入患儿声源定位特点及其中枢表现，探讨发现了语前聋晚植入耳蜗儿童静息态EEG功能网络连接异常。我们的研究结果显示行为学上双侧耳蜗植入儿童的声源定位特点为双侧声源定位能力大致对称，辨别0°方位的定位能力最佳，这与正常听力儿童表现一致，但在各个方位均差于正常听力儿童。而单侧耳蜗植入儿童的声源定位特点为植入侧与植入对侧声源定位能力不对称，声源定位能力范围局限于植入侧，且显著差于正常听力儿童和双侧耳蜗植入儿童。我们进一步发现在声源定位任务中，正常听力儿童出现了双侧颞上回区域的激活，提示双侧颞上回区域参与声源定位过程。双侧耳蜗植入儿童也出现了此区的激活，且强度较正常听力儿童更高。除此之外，双侧耳蜗植入儿童还出现了双侧Broca区激活。这说明双侧耳蜗植入儿童可能利用了与正常听力儿童相同的听觉信息，并通过类似的脑区处理过程进行声源定位，但由于皮层发育不成熟及其通过耳蜗获取的信息量不足，需要调用更多的脑区和更多的能量完成声源定位任务。在声源定位任务中，单侧耳蜗植入儿童在双侧颞上回、双侧Broca区未出现激活，而表现为左侧颞叶皮层的整体非特异性激活。这提示单侧耳蜗植入儿童的声源定位仍处于早期的阶段，无法利用与正常听力儿童一致的声源定位信息并通过类似的脑区处理过程进行声源定位，其声源定位能力弱于正常听力儿童和双侧耳蜗植入儿童。更进一步我们发现语前聋晚植入耳蜗儿童静息态EEG功能网络连接异常，结果显示，晚期人工耳蜗植入儿童听觉和视觉区域之间的功能连接更强但在θ和α波段的整体网络连接降低。说明植入年龄对大脑可塑性程度有重要影响，大脑功能网络连接的特征可能可以反映人工耳蜗植入儿童的康复程度。我们还发现皮质的激活情况与耳蜗儿的言语理解能力存在相关性，镜像刺激成功诱发了视听交互现象，且镜像机制可能能够反映或影响个体的言语水平。