Neuroanatomical studies on the information processing system in the primary facial taste center of fish

本研究从神经原子的角度揭示了鱼面部主要味觉中枢面叶（FL）的信息处理系统。本研究主要研究以下内容：1)三叉神经纤维向前叶的投射，2)前叶的细胞结构，3)前叶的传出纤维的测定，4)前叶的传出神经元向脑干的投射，5)鲶鱼的味蕾和神经纤维在倒刺中的分布。在6种鱼类中发现了三叉神经纤维在FL上的突起。这种凸出在鲶鱼身上尤其明显；三叉神经纤维体位性地投射到前叶，分布在除干尾小叶外的整个前叶区域，说明三叉神经纤维在鲶鱼前叶以及面神经的机械感觉纤维中做出了清晰的体感图。小的神经元（7-9个）和大的神经元（15-20 * 12-15个）存在于Plotosus的小叶中。小神经元在小叶中形成细胞簇，大神经元分散在小叶中。高尔基分析显示，小的神经元周围有50-60微米的树突场，而大的神经元周围有150微米长的厚树突。大的神经元及其树突完全被其他纤维的突触末梢所包围。向上（SSTN）或下（ISTN）次级味觉核投射的传出神经元被确定为大类型的神经元。上升神经元数量多且分散在小叶中，而下降神经元数量少且仅位于小叶的外周边缘。每个小叶中的上行神经元投射到位于小脑下方的整个SSTN区域。这表明SSTN中不存在体位组织，并支持了先前的电生理学发现，即SSTN中的每个神经元对体表的机械或味觉刺激具有广泛的感受野。味蕾在杠铃中的分布并不均匀。它们最密集地分布在沿倒刺长轴的吻侧或尾侧表面，少数分布在吻侧和尾侧之间的中间表面。神经纤维在上皮下形成中性网络，每个网络在吻侧或尾侧表面比中间表面小。少

This sutdy was undertaken to reveal neuronatomically the information processing system in the primary facial taste center, facial lobe (FL) of fish. The followings were mainly examined in this study ; 1)the projections of trigeminal fibers to the FL,2)cytoarchitecture of the FL,3)determination of the efferent fibers in the FL,4)projections of the efferent neurons in the FL to the brain stem, and 5)distribution of taste buds and nerve fibers in the barbels in catfish.The projection of trigeminal fibers onto the FL were found in 6 species of fish. This projection was especially noticeable in the catfishes ; the trigeminal fibers project somatotopically to the FL and distribute in the entire region of the FL except the trunk-tail lobule, indicating that trigeminal fibers contribute to make sharply defined somatosensory map in the FL of the catfish as well as the mechanosensory fibers of the facial nerve. Small (7-9 mum) and large sized (15-20 * 12-15 mum) neurons are present in the barbel … More lobules of Plotosus. Small neurons form cell clusters in the lobules and large neurons are scattered in the lobule. Golgi analyzes revealed that the small neurons are possessed of 50-60 mum dendritic fields around them, while the larger ones have thick dendrites of 150 mum in length. Large sized neurons and their dendrites were entirely surrounded by synaptic terminals of other fibers. Efferent neurons projecting to the superior (SSTN) or inferior (ISTN) secondary taste nuclei were determined as large types of neurons. Ascending neurons were numerous and scattered throughout the lobules, while descending neurons were small in number and located only in the peripheral margin of the lobules. Ascending neurons in each lobule projects to the entire regions of the SSTN located under the cerebellum. This shows that somatotopic organization is not present in the SSTN and support the previous electrophysiological findings that each neuron located in the SSTN has a wide receptive field in response to mechanical or taste stimulation of body surface.The taste buds were not uniformaly distributed in the barbels. They were most densely located in the rostral or caudal surface along the long axis of the barbels and few in the intermediate surface between the rostral and caudal surfaces. The nerve fibers make neutral networks under the epithelium and each network becomes smaller in the rostral or caudal surface than in the intermediate surface. Less