Auditory Plasticity in Cochlear Implant Animal Model

目前尚不清楚每位植入人工耳蜗（CI）的患者在术前能获得多少言语辨别能力。本研究的目的是寻找一种有效的方法，以预测言语辨别能力（听觉可塑性），在使用Cl动物模型，也与病人。I. Cl动物模型的听觉可塑性：电极插入耳蜗的大鼠（Cl动物模型）。比较模型组和对照组大鼠电驱动听性脑干反应（EABR）的差异。EABR阈值无明显差异，但相对于刺激强度的振幅增长曲线有显著差异，动物模型的陡度较小。这表明电刺激诱发的听神经纤维数目在实验组明显少于对照组。由于波幅增长曲线的陡度反映了听神经存活的程度，因此可以作为术后言语辨别能力的良好指标。电刺激耳蜗后，检测脑干Fos蛋白的出现。由于背侧皮质核含有大量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患者的言语辨别评分和电生理参数进行了一年多的研究。结果显示，各参数均出现了积极变化。因此，在CI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.