Lamb C F, Finger T E
Department of Cellular and Structural Biology, University of Colorado Health Sciences Center, Denver 80262, USA.
J Comp Neurol. 1996 Feb 19;365(4):585-93. doi: 10.1002/(SICI)1096-9861(19960219)365:4<585::AID-CNE6>3.0.CO;2-0.
The second gustatory nucleus of teleost fishes receives ascending fibers from the primary gustatory center in the medulla and sends efferent fibers to several nuclei in the inferior lobe of the diencephalon. Similar to the corresponding parabrachial nucleus in birds and mammals, the secondary gustatory nucleus of catfish consists of several cytoarchitectonically distinct subnuclei which receive input from different portions of the primary gustatory nuclei. However, it is unclear how the subnuclear organization relates to the processing of gustatory information in the hindbrain and the subsequent transmission of that information to the forebrain. To determine whether cells within different subnuclei of the secondary gustatory nucleus of channel catfish project to different diencephalic targets, single cells were intracellularly labeled with biocytin. Three subnuclei have been identified in the secondary gustatory nucleus: a medial subnucleus spanning most of the rostrocaudal extent of the nucleus, a central subnucleus and a dorsal subnucleus, the latter two located in the rostrolateral portion of the complex. Cells throughout the secondary gustatory nucleus typically possessed similar collateral projections to several nuclei in the inferior lobe, although four of the six cells filled in the medial subnucleus projected only to nucleus centralis. The only apparent subnucleus-specific projection pattern involved cells at the rostral edge of the secondary gustatory nucleus and in the secondary visceral nucleus. Axons of these cells terminated only in restricted portions of nucleus lobobulbaris. These results suggest that efferents from different subnuclei of the secondary gustatory nucleus of catfish, like those of the parabrachial nucleus of birds and mammals, do not possess simple, topographical projections to target nuclei in the diencephalon.
硬骨鱼的第二味觉核接收来自延髓初级味觉中枢的上行纤维，并将传出纤维发送至间脑下叶的几个核。与鸟类和哺乳动物中相应的臂旁核相似，鲶鱼的次级味觉核由几个细胞结构上不同的亚核组成，这些亚核接收来自初级味觉核不同部分的输入。然而，尚不清楚亚核组织如何与后脑味觉信息的处理以及随后该信息向前脑的传递相关。为了确定鲶鱼次级味觉核不同亚核内的细胞是否投射到不同的间脑靶标，用生物胞素对单细胞进行细胞内标记。在次级味觉核中已鉴定出三个亚核：一个内侧亚核，跨越该核大部分的前后范围；一个中央亚核和一个背侧亚核，后两者位于复合体的 rostrolateral 部分。整个次级味觉核中的细胞通常对下叶的几个核具有相似的侧支投射，尽管在内侧亚核中填充的六个细胞中有四个仅投射到中央核。唯一明显的亚核特异性投射模式涉及次级味觉核 Rostral 边缘和次级内脏核中的细胞。这些细胞的轴突仅终止于 lobobulbaris 核的受限部分。这些结果表明，鲶鱼次级味觉核不同亚核的传出纤维，与鸟类和哺乳动物的臂旁核一样，对间脑靶核不具有简单的拓扑投射。
