Raabe Tobias, Köppl Christine
Lehrstuhl für Zoologie, Technische Universität München, Lichtenbergstrasse 4, 85748 Garching, Germany.
Brain Res. 2003 Oct 3;986(1-2):124-31. doi: 10.1016/s0006-8993(03)03221-9.
The efferent innervation of the auditory basilar papilla of birds and mammals is provided by a dedicated population of brainstem neurones that are separate from those supplying the vestibular organs. This study addresses the question whether a population of bilaterally-projecting efferents, contacting hair cells in both basilar papillae, is consistently present in birds. The chicken and the barn owl were chosen, two species where the total number of efferents was already known and which represent two extremes of an auditory generalist and an auditory specialist, respectively. Fluorogold and Choleratoxin, two potent retrograde tracers, were injected into one cochlear duct each of all individuals. Labelled neurones were subsequently identified in the brainstem using standard fluorescence techniques. A small proportion (up to 2% of the total population) of double-labelled cells was found in both species. The great majority of those double-labelled neurones could be assigned to the ventrolateral group of efferents, which has previously been shown to project exclusively to the auditory basilar papilla. Thus, in birds, like in mammals, a small subgroup of auditory efferents innervates both basilar papillae.
鸟类和哺乳动物听觉基底乳头的传出神经支配由一群专门的脑干神经元提供，这些神经元与供应前庭器官的神经元不同。本研究探讨了在鸟类中是否始终存在一群双侧投射的传出神经元，它们与两个基底乳头中的毛细胞接触。研究选择了鸡和仓鸮，这两个物种的传出神经元总数已经为人所知，它们分别代表听觉通才和听觉专家的两个极端。将两种有效的逆行示踪剂荧光金和霍乱毒素分别注入所有个体的一个耳蜗管中。随后使用标准荧光技术在脑干中识别标记的神经元。在这两个物种中都发现了一小部分（占总数的2%）双标记细胞。这些双标记神经元中的绝大多数可归为传出神经元的腹外侧组，先前已证明该组仅投射到听觉基底乳头。因此，与哺乳动物一样，在鸟类中，一小部分听觉传出神经元支配两个基底乳头。
