Auditory Plasticity in Cochlear Implant Animal Model

每个人工耳蜗（Cl）患者在手术前能获得多少言语辨别能力尚不清楚。本研究旨在寻找一种有效的方法来预测Cl动物模型和患者的言语辨别能力（听觉可塑性）。1 . Cl动物模型的听觉可塑性：将电极插入新生儿聋大鼠耳蜗（Cl动物模型）。比较Cl模型大鼠与对照组大鼠电驱动听觉脑干反应（EABR）。EABR阈值差异不显著，但相对于刺激强度的幅值增长曲线差异显著；动物模型的陡度较小。这说明电刺激引起的听神经纤维数量比对照组少。振幅增长曲线的陡峭程度反映了听神经的存活程度，是判断术后言语识别能力的良好指标。耳蜗电刺激后脑干检测Fos蛋白的出现。由于耳蜗背核中含有大量的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 . Cl患者的听觉可塑性：对Cl患者一年多的言语辨别评分和电生理参数进行了研究。结果显示各参数均有正向变化。因此，在Cl患者中也证实了听觉可塑性。

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.