Zeng Fan Gang
Departments of Otolaryngology, Anatomy and Neurobiology, Biomedical Engineering and Cognitive Sciences, University of California, Irvine, CA 92697, USA.
Hear Res. 2002 Dec;174(1-2):101-6. doi: 10.1016/s0378-5955(02)00644-5.
Both place and temporal codes in the peripheral auditory system contain pitch information, however, their actual use by the brain is unclear. Here pitch data are reported from users of the cochlear implant, which provides the ability to change the temporal code independently from the place code. With fixed electrode stimulation, both frequency discrimination and pitch estimate data show that the cochlear implant users can only discern differences in pitch for frequencies up to about 300 Hz. An integration model can predict pitch estimation from frequency discrimination, reinforcing Fechner's hypothesis relating sensation magnitude to stimulus discriminability. The present results suggest that 300 Hz is the upper boundary of the temporal code and that the absolute place information should be included in the present pitch models. They further suggest that future cochlear implants need to increase the number of independent electrodes to restore normal pitch range and resolution.
在外周听觉系统中，位置编码和时间编码都包含音高信息，然而，大脑对它们的实际使用情况尚不清楚。在此报告了来自人工耳蜗使用者的音高数据，人工耳蜗能够独立于位置编码来改变时间编码。在固定电极刺激下，频率辨别和音高估计数据均表明，人工耳蜗使用者只能辨别高达约300赫兹频率的音高差异。一个整合模型可以根据频率辨别来预测音高估计，这强化了费希纳将感觉强度与刺激辨别力相关联的假设。目前的结果表明，300赫兹是时间编码的上限，并且当前的音高模型应纳入绝对位置信息。这些结果还表明，未来的人工耳蜗需要增加独立电极的数量，以恢复正常的音高范围和分辨率。
