Köppl C
Institut für Zoologie, Technische Universität München, Garching, Germany.
J Assoc Res Otolaryngol. 2001 Mar;2(1):41-53. doi: 10.1007/s101620010027.
The nucleus angularis (NA), one of the two cochlear nuclei of birds, plays an important role in the processing of sound intensity. To begin investigating the NA in detail in the barn owl, which is a popular animal model for neural mechanisms of sound localization, a frequency map for this nucleus is presented here. Focal injections of horseradish peroxidase or neurobiotin were placed either in the NA or in the cochlear nucleus magnocellularis, labeling small groups of auditory nerve fibers of known characteristic frequency (CF) from 0.25 to 9.6 kHz. The courses of their axonal branches were used to construct a composite average map of the tonotopic frequency representation in the nucleus angularis. Nucleus angularis in the barn owl, as seen in frontal sections, resembles a sheet of cells bent approximately into an S shape. The lowest frequencies were found represented at the ventromedial extreme. The representation of increasingly higher frequencies then followed the S shape, with the highest frequencies located at the ventrolateral tip. Auditory nerve fibers of a given CF always entered the nucleus angularis within a well-restricted area and then traveled along their isofrequency band within the NA while branching off terminals. The isofrequency bands were typically slanted from caudo-ventro-medial to rostro-dorso-lateral. The basic tonotopic organization is comparable to that found in other birds, the major differences being the large size and unusual shape of the barn owl's nucleus angularis.
角状核（NA）是鸟类的两个耳蜗核之一，在声音强度处理中起重要作用。为了开始在谷仓猫头鹰中详细研究NA，谷仓猫头鹰是声音定位神经机制的常用动物模型，本文给出了该核的频率图。将辣根过氧化物酶或神经生物素局部注射到NA或耳蜗大细胞核中，标记出特征频率（CF）从0.25至9.6千赫兹的小群听觉神经纤维。利用它们轴突分支的走向构建了角状核中音频频率表征的复合平均图。在额状切面上观察到，谷仓猫头鹰的角状核类似于一片大致弯曲成S形的细胞。最低频率出现在腹内侧极端。随后，越来越高的频率表征沿S形分布，最高频率位于腹外侧尖端。给定CF的听觉神经纤维总是在一个严格受限的区域内进入角状核，然后在NA内沿着它们的等频带行进，同时分支形成终末。等频带通常从尾腹内侧向嘴背外侧倾斜。基本的音频组织与在其他鸟类中发现的类似，主要区别在于谷仓猫头鹰角状核的尺寸大且形状异常。
