TOPOGRAPHY OF DESCENDING PROJECTIONS FROM THE INFERIOR COLLICULUS TO AUDITORY BRAIN-STEM NUCLEI IN THE RAT
TOPOGRAPHY OF DESCENDING PROJECTIONS FROM THE INFERIOR COLLICULUS TO AUDITORY BRAIN-STEM NUCLEI IN THE RAT
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DOI：
10.1002/cne.903280305
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发表时间：
1993-02-15
影响因子：
2.5
通讯作者：
HERBERT, H
中科院分区：
文献类型：
--
作者：
CAICEDO, A;HERBERT, H
应用顺行轴突示踪剂菜豆-白细胞凝集素（Phaseolusvulgaris-leucoagglutinin，PHA-L）研究了大鼠下丘（IC）向听性脑干核团、脑桥核团和网状核团的下行投射的组织结构。将PHA-L注射到IC的细胞学上确定的亚核中，发现每个亚核都有独特的传出投射模式，IC的中央核按拓扑顺序投射到外侧丘系背核（DLL）、头侧橄榄周核（RPO）、斜方体腹侧核（VNTB）和耳蜗背核（DCN）。假设该地形图表示耳蜗位置布置。IC的外部皮质投射到鞍核（Sag）、RPO、VNTB和DCN。小的投射被发现到脑桥和网状核。来自IC背侧皮质的传出纤维主要终止于凹陷，而听觉和听外脑干的其他核团仅接收较小的投射。丘间区向DLL发送中等数量的纤维，很少（如果有的话）向其余的听觉脑干核团发送纤维。相比之下，从丘间区到网状结构的投射相当强。目前的数据表明，IC的四个亚核具有向脑桥和延髓脑干核的下行投射的差异模式。这些平行的离丘神经通路，假设属于功能独立的电路，可能会调节听觉处理在不同层次的听觉神经轴。
We examined the organization of descending projections from the inferior colliculus (IC) to auditory brainstem nuclei and to pontine and reticular nuclei in the rat by employing the anterograde axonal tracer Phaseolus vulgaris-leucoagglutinin (PHA-L). Small PHA-L injections into cytologically defined subnuclei of the IC revealed that each subnucleus has a unique pattern of efferent projections.The central nucleus of the IC projects in a topographic order to the dorsal nucleus of the lateral lemniscus (DLL), the rostral periolivary nucleus (RPO), the ventral nucleus of the trapezoid body (VNTB), and the dorsal cochlear nucleus (DCN). It is assumed that this topography represents a cochleotopic arrangement. The external cortex of the IC projects to the nucleus sagulum (Sag), the RPO, the VNTB, and the DCN. Minor projections were found to pontine and reticular nuclei. Efferent fibers from the dorsal cortex of the IC terminate mainly in the Sag, while other nuclei of the auditory and extra-auditory brainstem receive only minor projections. The intercollicular zone sends a moderate number of fibers to the DLL and very few, if any, to the remaining auditory brainstem nuclei. In contrast, fairly strong projections from the intercollicular zone to the reticular formation were found.The present data demonstrate that the four subnuclei of the IC have a differential pattern of descending projections to nuclei in the pontine and medullary brainstem. These parallel colliculofugal pathways, assumed to belong to functionally separate circuits, may modulate auditory processing at different levels of the auditory neuraxis.