Nerve Fiber-circuits of Gustatory Sence

采用顺行示踪剂（生物素化右旋糖酐胺：BDA）和顺行/逆行示踪剂（小麦-胚芽凝集酶-辣根过氧化酶：WGA-HRP）的示踪方法，研究了大鼠丘脑味觉核即后内侧腹侧丘脑核（VPMpc）的细胞内部分向前脑区域的投射。BDA注射到VPMpc后，在岛叶皮质、杏仁核复合体和纹状眼底观察到末端标记。杏仁核复合体的末端标记分布在外侧杏仁核吻侧背外侧区和中央杏仁核外侧分支吻侧区。中央杏仁核的末端标记延伸至纹状眼底。WGA-HRP逆行示踪研究显示，从VPMpc到杏仁核复合体的投射纤维起源于VPMpc内侧部分，也起源于VPMpc内侧的丘脑区。在脑岛皮层和杏仁核复合体分别注射氟金和WGA-HRP的大鼠，VPMpc内未发现双标记的神经元细胞体，但VPMpc内内侧单氟金标记的神经元与单WGA-HRP标记的神经元混杂在一起。结果表明，投射到杏仁核复合体的VPMpc神经元与投射到岛叶皮层的VPMpc神经元构成不同的群体。

Projections from the thalamic gustatory nucleus, i.e. the parvicellular part of the posteromedial ventral thalamic nucleus (VPMpc) to the forebrain regions were studied in the rat by the tract-tracing methods with anterograde tracer (biotinylated dextran amine: BDA) and anterogfade/retrograde tracer (wheat-germ aggluti ni n-horseradish peroxidase: WGA-HRP). After BDA injection into the VPMpc, terminal labeling was observed in the insular cortex, amygdaloid complex, and fundus striati. The terminal labeling in the amygdaloid complex was distributed in dorsolateral area of the rostral part of the lateral amygdaloid nucleus and the rostral part of the lateral subdivision of the central amygdaloid nucleus. The terminal labeling in the central amygdaloid nucleus extended to the fundus striati. The retrograde tracing study with WGA-HRP revealed that the projection fibers from the VPMpc to the amygdaloid complex originated from the medial part of the VPMpc and also from the thalamic area medial to the VPMpc. In the rats injected with Fluoro-Gold and WGA-HRP respectively into the insular cortex and amygdaloid complex, no double-labeled neuronal cell bodies were found in the VPMpc, although neurons labeled singly with Fluoro-Gold were intermingled with those singly labeled with WGA-HRP in the- medial part of the VPMpc. The results indicated that VPMpc neurons projecting to the amygdaloid complex constituted a population different from VPMpc neurons projecting to the insular cortex.