Liu X, McPhee G, Seldon H L, Clark G M
Department of Otolaryngology, The University of Melbourne, Australian Bionic Ear and Hearing Research Institute, Vic.
Hear Res. 1997 Dec;114(1-2):264-74. doi: 10.1016/s0378-5955(97)00170-6.
To rehabilitate profoundly deaf patients who are not suitable for cochlear implants, central auditory prostheses have been implanted. To compare two possible electrode configurations - penetrating and surface ones - electrical stimulation of the cochlear nucleus with both types of arrays was tested on guinea pigs and cats. Electrophysiological, autoradiographic and histological measures were used to study effects of the central auditory prostheses on the auditory pathway. The results showed that a successful electrically evoked auditory brainstem response could be recorded with both surface and penetrating electrodes in cats and guinea pigs. In guinea pigs the penetrating electrodes had advantages over surface arrays in the sense of lower thresholds and wider dynamic ranges. In cats penetrating electrodes showed lower thresholds than surface ones. In cats and guinea pigs stimulated with either surface or penetrating electrodes, evoked 2-deoxyglucose (2-DG) label was found in the auditory pathway from the cochlear nucleus to the inferior colliculus. No non-auditory tissues were found with evoked 2-DG label. Histological results showed that in subdivisions of the guinea pig cochlear nucleus stimulated with penetrating electrodes the neurone density was decreased, and the mean soma area was increased compared with the control side. In the cat, penetrating electrodes were associated only with increased mean soma area in parts of the stimulated cochlear nucleus. These results suggest that the physiological advantages of penetrating electrodes over surface ones were achieved with some trade-off in safety, especially in the guinea pig.
为了使不适合植入人工耳蜗的极重度聋患者恢复听力，已植入了中枢听觉假体。为了比较两种可能的电极配置——穿透式和表面式，在豚鼠和猫身上测试了用这两种阵列对耳蜗核进行电刺激的效果。采用电生理、放射自显影和组织学测量方法来研究中枢听觉假体对听觉通路的影响。结果表明，在猫和豚鼠身上，使用表面电极和穿透电极都能成功记录到电诱发听觉脑干反应。在豚鼠中，穿透电极在阈值较低和动态范围较宽方面比表面阵列具有优势。在猫中，穿透电极的阈值比表面电极低。在用表面电极或穿透电极刺激的猫和豚鼠中，在从耳蜗核到下丘的听觉通路中发现了诱发的2-脱氧葡萄糖（2-DG）标记。未发现有诱发2-DG标记的非听觉组织。组织学结果表明，在豚鼠耳蜗核中，用穿透电极刺激的亚区与对照侧相比，神经元密度降低，平均胞体面积增加。在猫中，穿透电极仅与受刺激的部分耳蜗核中的平均胞体面积增加有关。这些结果表明，穿透电极相对于表面电极的生理优势是以安全性方面的一些权衡为代价的，尤其是在豚鼠中。
