Møller Aage R
School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, Tex., USA.
Adv Otorhinolaryngol. 2006;64:206-223. doi: 10.1159/000094653.
Cochlear implants bypass functions of the cochlea that have been regarded to be fundamental for discrimination of the frequency (or spectrum). Frequency discrimination is essential for discrimination of sounds, including speech sounds, and the normal auditory system is assumed to make use of both (power) spectral and temporal information for frequency discrimination. Spectral information is represented by the place on the basilar membrane that generates the largest amplitude of vibration on the basilar membrane. Evidence has been presented that the temporal representation of frequency is more robust than the place representation and thus regarded more important for speech discrimination. The fact that some cochlear implants provide good speech discrimination using only information about the energy in a few spectral bands seems to contradict these studies. In that way, frequency discrimination may be similar to trichromatic color vision, which is based on the energy in only three different spectral bands of light, accomplished by different color-sensitive pigments in the cones of the retina. Cochlear nucleus implants (ABIs) also bypass the auditory nerve, which does not perform any processing. Therefore, it may be expected that ABIs are equally efficient as cochlear implants. However, experience from the use of ABIs in patients with bilateral vestibular schwannoma has not been encouraging, but recent studies of the use of ABIs in patients with other causes of injuries to the auditory nerve have shown similar speech discrimination as achieved with modern cochlear implants. Cochlear implants and ABIs are successful in providing speech discrimination because of redundancy in the processing in the ear, redundancy of the speech signal and because the auditory nervous system has a high degree of plasticity. Expression of neural plasticity makes the auditory nervous system adapt to the change in demands of processing of the information provided by cochlear implants.
人工耳蜗绕过了耳蜗中那些被认为对频率（或频谱）辨别至关重要的功能。频率辨别对于包括语音在内的声音辨别至关重要，正常听觉系统被认为利用（功率）频谱和时间信息来进行频率辨别。频谱信息由基底膜上产生最大振动幅度的位置来表示。已有证据表明，频率的时间表征比位置表征更稳健，因此被认为对语音辨别更重要。一些人工耳蜗仅使用少数几个频谱带中的能量信息就能实现良好的语音辨别，这一事实似乎与这些研究相矛盾。这样一来，频率辨别可能类似于三色视觉，后者仅基于光的三个不同频谱带中的能量，由视网膜视锥细胞中不同的颜色敏感色素来完成。耳蜗核植入物（ABI）也绕过了不进行任何处理的听神经。因此，可以预期ABI与人工耳蜗的效率相当。然而，双侧前庭神经鞘瘤患者使用ABI的经验并不令人鼓舞，但最近对其他听神经损伤原因患者使用ABI的研究表明，其语音辨别能力与现代人工耳蜗相当。人工耳蜗和ABI能够成功实现语音辨别，是因为耳朵处理过程中的冗余、语音信号的冗余以及听觉神经系统具有高度可塑性。神经可塑性的表达使听觉神经系统能够适应人工耳蜗所提供信息处理需求的变化。
