Connections and frequency representation in the auditory brainstem of the mustache bat, Pteronotus parnellii.
Connections and frequency representation in the auditory brainstem of the mustache bat, Pteronotus parnellii.
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小胡子蝙蝠 Pteronotus parnellii 听觉脑干的连接和频率表示。
DOI：
10.1002/cne.902900206
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发表时间：
1989
期刊：
影响因子：
--
通讯作者：
Leake,PA
中科院分区：
文献类型：
--
作者：
Zook,JM;Leake,PA
本研究的目的是描述的耳蜗频率图的胡子蝙蝠，Pteronotus parnellii，并与组织的耳蜗初级传入的二级预测从耳蜗核的上级橄榄复合体。辣根过氧化物酶（HRP）的小存款被放置在耳蜗核的生理特征相对于单位最佳频率的网站。从存款，标记的纤维被追溯到耳蜗的逆行方向和顺行方向的上级橄榄。用光学显微镜和电子显微镜检查实验动物和对照动物的角膜。为了定量的神经支配密度的异常变化沿着耳蜗螺旋的胡子蝙蝠的螺旋神经节神经元的外周轴突计数。在耳蜗底回的起始和结束处发现神经支配密度增加的区域。最高的耳蜗神经支配密度始终发生在上基底回。在辣根过氧化物酶示踪实验中，这个区域包含标记的纤维，只有当HRP存款在耳蜗核内的单位最佳频率约60 kHz的网站。这些发现支持了Kossl和Vater的建议（'85），即耳蜗部位的神经支配密度增加与这种回声定位蝙蝠在60 kHz频带分析时对神经和行为的强调有关。耳蜗、耳蜗核和上级橄榄核内音调定位图的一般排列与以前在这种蝙蝠和其他哺乳动物物种中的观察结果一致。在所有这三个层次上，都有证据表明，60 kHz左右的频率有不成比例的大代表性，类似于小胡子蝙蝠下丘和听觉皮层内报告的放大代表性。在所有的情况下，有一个一致的HRP存款的大小和数量之间的关系和分布的耳蜗逆行标记的神经元。在大多数情况下，存款的大小和终端arborization领域的顺行标记的纤维在上级橄榄之间有类似的关系。然而，在与60 kHz频带相关的沉积物的情况下，标记的树枝状化场的大小是从沉积物的大小和耳蜗中标记的程度预期的两倍多。这些病例表明，在耳蜗和耳蜗核中已经过度代表的60 kHz左右的频率的代表性，可以在上级橄榄复合体的水平上进一步扩展。
The goals of this study were to describe the cochlear frequency map of the mustache bat, Pteronotus parnellii, and to relate the organization of cochlear primary afferents to that of the second-order projections from the cochlear nucleus to the superior olivary complex. Small deposits of horseradish peroxidase (HRP) were placed in the cochlear nucleus at sites that were physiologically characterized with respect to unit-best frequency. From the deposits, labeled fibers were traced in the retrograde direction to the cochlea and in the anterograde direction to the superior olive. Cochleas from both experimental and control animals were examined with light and electron microscopy. The peripheral axons of spiral ganglion neurons were counted in order to quantify the unusual variation in the innervation density along the cochlear spiral of the mustache bat. Regions of increased innervation density were found at the beginning and end of the basal turn of the cochlea. The highest cochlear innervation density consistently occurred in the upper basal turn. In horseradish peroxidase tracing experiments, this region contained labeled fibers only when HRP deposits were made at sites within the cochlear nucleus with unit-best frequencies around 60 kHz. These findings support the suggestion (Kossl and Vater,'85) that the cochlear sites of increased innervation density are related to the neural and behavioral emphasis that this echolocating bat places upon the analysis of the 60 kHz frequency band.The general arrangement of tonotopic maps within the cochlea, cochlear nucleus, and superior olive was consistent with previous observations in this bat and other mammalian species. At all three levels, there was evidence of a disproportionately large representation of frequencies around 60 kHz, similar to the enlarged representation reported within the inferior colliculus and auditory cortex of the mustache bat. In all cases there was a consistent relation between the size of the HRP deposit and the number and distribution of retrogradely labeled neurons in the cochlea. For most cases there was a similar relation between the size of the deposit and the terminal arborization field of anterogradely labeled fibers in the superior olive. However, in cases with deposits associated with the 60 kHz frequency band, the size of the labeled arborization field was more than twice as large as expected from the size of the deposits and from the extent of labeling in the cochlea. These cases suggest that the representation of frequencies around 60 kHz, already overrepresented in both the cochlea and cochlear nucleus, may be further expanded at the level of the superior olivary complex.