Auditory Plasticity in Cochlear Implant Animal Model

目前尚不清楚每个人工耳蜗术前患者能获得多少言语辨别能力。本研究旨在为应用氯化动物模型预测言语辨别能力(听觉可塑性)提供有用的方法。1.氯化动物模型的听觉可塑性：将电极植入新生耳聋大鼠的耳蜗处(氯化动物模型)。比较电驱动听性脑干反应(EABR)模型大鼠和对照组大鼠的EABR。EABR阈值无差异，但波幅增长曲线与刺激强度有显著差异，动物模型的波幅增长曲线的陡度较小。提示耳聋动物电刺激诱发的听神经纤维数量明显少于对照组。由于波幅增长曲线的陡度反映了听神经存活的程度，因此可作为术后言语辨别能力的良好指标。电刺激耳蜗区后，观察脑干Fos蛋白的表达。由于耳蜗背核内含有大量的Fos阳性神经元，该区域被认为是电驱动听觉的重要部位之一。II.认知障碍患者的听觉可塑性：对认知障碍患者的言语辨别能力和电生理参数进行了一年多的研究。结果显示，各项参数均有正向变化。因此，CL患者的听觉可塑性也得到了证实。

It was not known that each Cochlear Implant (Cl) patients can obtain how much speech discrimination ability prior to the operation. This study aimed to find the useful method in order to predict speech discrimination ability (auditory plasticity) in using Cl animal model and also with the patients.I.Auditory plasticity in Cl animal model : The electrodes were inserted in the cochlea of neonatally deafended rats (Cl animal model). Electricaly driven auditory brainstem response (EABR) was compared between Cl model and control rats. The threshold of EABR showed no difference, but the ampltitude growth curve relative to the stimulus intensity showed significant difference ; the steepness was smaller in animal model. This indicated that the number of auditory nerve fibers evoked by the electric stimulation was smaller in deafended animal than the controls. As the steepness of amplitude growth curve reflected the extent of surviving auditory nerve, it became a good indicator for post-operative speech discrimination ability. The brainstem was examined for the appearance of Fos protein following the electric stimulation in the cochlea. As the dorsal conchlear nucleus contained large number of Fos positive neurons, this region was thought to be one of the important site for electrically driven auditory sensation.II.Auditory plasticity in Cl patients : Speech discrimination scores and the electrophysiological parameters were studied for over a year in Cl patients. The results revealed positive change in each parameters. Thus, auditory plasticity was also proved in Cl patients.