Malmierca M S, Le Beau F E, Rees A
Department of Physiological Sciences, University of Newcastle upon Tyne Medical School, UK.
Hear Res. 1996 Apr;93(1-2):167-80. doi: 10.1016/0378-5955(95)00227-8.
We describe the descending projections from the central nucleus of the inferior colliculus (CNIC) in guinea pig. Focal injections of the tracer biocytin, made in physiologically defined frequency regions of the CNIC, labelled laminated axonal terminal fields in the ipsilateral dorsal nucleus of the lateral lemniscus, and bilaterally in the ventral nucleus of the trapezoid body and the dorsal cochlear nucleus. Labelling was also present in the rostral periolivary nucleus, but we could not distinguish a clear border between the terminal fields in this nucleus and those in the ventral nucleus of the trapezoid body. Labelling observed in the ventral nucleus of the lateral lemniscus, and to a lesser extent in the dorsal nucleus of the lateral lemniscus, was accompanied by retrogradely labelled somata and therefore we cannot conclude unequivocally that the CNIC projects to these lemniscal nuclei. Where the labelling was ordered topographically, its position varied as a function of the best frequency at the injection site. High-frequency regions in the CNIC project to the medial parts of the ventral nucleus of the trapezoid body and dorsal cochlear nucleus, while low-frequency regions in the CNIC project to the lateral parts of the ventral nucleus of the trapezoid body and dorsal cochlear nucleus. Additional axonal labelling with terminal boutons, but with no apparent topographical arrangement, was present in the ipsilateral horizontal cell group, sagulum, and also bilaterally in the superficial granule cell layer of the ventral cochlear nucleus and layer 2 of the dorsal cochlear nucleus. Our findings are consistent with the existence of tonotopically organised feedback projections from the CNIC to the brainstem nuclei that project to it.
我们描述了豚鼠下丘中央核（CNIC）的下行投射。在CNIC生理定义的频率区域进行示踪剂生物素的局部注射，标记了同侧外侧丘系背核中的分层轴突终末场，以及双侧的斜方体腹核和蜗背侧核。在橄榄周核前部也有标记，但我们无法区分该核与斜方体腹核终末场之间的清晰边界。在外侧丘系腹核观察到的标记，以及在外侧丘系背核中程度较轻的标记，伴有逆行标记的胞体，因此我们不能明确得出CNIC投射到这些丘系核的结论。在标记按拓扑顺序排列的地方，其位置随注射部位的最佳频率而变化。CNIC中的高频区域投射到斜方体腹核和蜗背侧核的内侧部分，而CNIC中的低频区域投射到斜方体腹核和蜗背侧核的外侧部分。在同侧水平细胞群、垂悬束以及双侧的蜗腹侧核浅层颗粒细胞层和蜗背侧核第2层中还存在额外的轴突标记和终末小体，但没有明显的拓扑排列。我们的研究结果与存在从CNIC到投射至其的脑干核的音调组织反馈投射一致。
