Lamb C F, Caprio J
Department of Zoology and Physiology, Louisiana State University, Baton Rouge 70803-1725.
J Comp Neurol. 1993 Nov 15;337(3):400-18. doi: 10.1002/cne.903370305.
Vertebrate gustatory systems include a tertiary ascending pathway from a secondary gustatory nucleus in the hindbrain to several forebrain nuclei. This connection is prominent in catfish, corresponding to their highly developed sense of taste. Iontophoretic injections of horseradish peroxidase were used to identify the specific target nuclei of the tertiary gustatory pathway in channel catfish and to characterize those nuclei by their respective connections. Efferents from the secondary gustatory nucleus (nGS) ascend in the tertiary gustatory tract to the caudal inferior lobe, where they terminate caudally in the nucleus lobobulbaris (nLB) and nucleus centralis (nCLI), and rostrally in the nucleus diffusus (nDLI). Secondary projections from the facial lobe (FL) also terminate in the nLB and in the nucleus subglomerulus (nSG). The nLB forms three cell groups (caudal--nLB, rostrolateral--rl nLB, parvicellular--nLBp), which project to the facial lobe, vagal lobe, and telencephalon, respectively. Cells from the nCLI project throughout the caudal inferior lobe and to the acousticolateral torus semicircularis and telencephalon, while the nDLI and nSG have intrinsic connections within the inferior lobe. The lateral thalamic nucleus projects from this region back to the nGS. Through these identified connections several mechanisms for the processing of gustatory information can be proposed. The descending projections from the nLB and nLT could provide feedback to the primary and secondary gustatory nuclei, and could modulate feeding-related motor circuits in the medulla. The connections of nCLI and nLBp with the telencephalon allow for the involvement of gustation in learning processes and other complex behaviors.
脊椎动物的味觉系统包括一条从后脑的二级味觉核到几个前脑核的三级上行通路。这种连接在鲶鱼中很突出，这与它们高度发达的味觉相对应。使用离子电渗法注射辣根过氧化物酶来确定鲶鱼三级味觉通路的特定靶核，并通过它们各自的连接来表征这些核。来自二级味觉核（nGS）的传出纤维在三级味觉束中向上延伸至尾下叶，在那里它们在尾侧终止于延髓球核（nLB）和中央核（nCLI），在前侧终止于弥散核（nDLI）。来自面神经叶（FL）的二级投射也终止于nLB和肾小球下核（nSG）。nLB形成三个细胞群（尾侧——nLB、 rostrolateral——rl nLB、小细胞——nLBp），它们分别投射到面神经叶、迷走神经叶和端脑。来自nCLI的细胞投射到整个尾下叶以及听外侧半规管和端脑，而nDLI和nSG在下叶内有内在连接。外侧丘脑核从这个区域投射回nGS。通过这些已确定的连接，可以提出几种处理味觉信息的机制。来自nLB和nLT的下行投射可以向一级和二级味觉核提供反馈，并可以调节延髓中与进食相关的运动回路。nCLI和nLBp与端脑的连接使得味觉参与学习过程和其他复杂行为。
