Department of Neurobiology and Anatomical Sciences, University of Mississippi Medical Center, Jackson, Mississippi, 39216.
J Comp Neurol. 2013 Oct 15;521(15):3524-40. doi: 10.1002/cne.23369.
Perception of linear acceleration and head position is the function of the utricle and saccule in mammals. Nonmammalian vertebrates possess a third otolith endorgan, the macula lagena. Different functions have been ascribed to the lagena in arboreal birds, including hearing, equilibrium, homing behavior, and magnetoreception. However, no conclusive evidence on the function of the lagena in birds is currently available. The present study is aimed at providing a neuroanatomical substrate for the function of the lagena in the chicken as an example of terrestrial birds. The afferents from the lagena of chick embryos (E19) to the brainstem and cerebellum were investigated by the sensitive lipophilic tracer Neuro Vue Red in postfixed ears. The results revealed that all the main vestibular nuclei, including the tangential nucleus, received lagenar projections. No lagenar terminals were found in auditory centers, including the cochlear nuclei. In the cerebellum, the labeled terminals were found variably in all of the cerebellar nuclei. In the cerebellar cortex, the labeled fibers were found mostly in the uvula, with fewer afferents in the flocculus and paraflocculus. None was seen in the nodulus. The absence of lagenar afferent projections in auditory nuclei and the presence of a projection pattern in the vestibular nuclei and cerebellum similar to that of the utricle and saccule suggest that the primary role of the lagena in the chick lies in the processing of vestibular information related to linear acceleration and static head position.
哺乳动物的内淋巴囊和椭圆囊负责感知线性加速度和头部位置。非哺乳动物的脊椎动物拥有第三个耳石器官，即侧斑器。侧斑器在树栖鸟类中具有不同的功能，包括听觉、平衡、归巢行为和磁感觉。然而，目前尚无关于鸟类侧斑器功能的确凿证据。本研究旨在为鸡的侧斑器功能提供神经解剖学基础，鸡是陆地鸟类的代表。通过在固定后的耳朵中使用脂溶性示踪剂 NeuroVue Red，研究了鸡胚胎（E19）的侧斑器传入到脑干和小脑的传入纤维。结果表明，所有主要的前庭核，包括切线核，都接收侧斑器的投射。在听觉中枢，包括耳蜗核，都没有发现侧斑器末端。在小脑，标记的末端在所有小脑核中都有不同程度的出现。在小脑皮质中，标记的纤维主要出现在绒球，在小脑前叶和小脑后叶的传入纤维较少。在小结中则没有。侧斑器传入纤维在听觉核中的缺失以及在前庭核和小脑中的投射模式类似于内淋巴囊和椭圆囊，这表明侧斑器在鸡中的主要作用是处理与线性加速度和头部静态位置相关的前庭信息。
