Evolution of cerebellum-like structures
Evolution of cerebellum-like structures
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DOI：
10.1159/000063567
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发表时间：
2002-01-01
影响因子：
1.7
通讯作者：
Bell, CC
中科院分区：
文献类型：
--
作者：
Bell, CC
所有脊椎动物的大脑都有一个小脑，其中大多数还有一个或多个在组织学上与小脑相似的额外结构。小脑样结构包括大多数水生脊椎动物的内侧八侧核、许多具有电感觉系统的水生脊椎动物的背侧八侧核、辐鳍鱼的视顶盖边缘层、少数具有电感觉系统的高级硬骨鱼群的电感觉叶、少数广泛分布的硬骨鱼群的丘脑吻外侧核、少数具有电感觉系统的硬骨鱼群的视顶盖边缘层、少数具有电感觉系统的高级硬骨鱼群的视顶盖边缘层和少数具有电感觉系统的高级硬骨鱼群的视顶盖边缘层。和耳蜗背核，除了单孔类动物。所有这些结构都在其深层接受地形组织的感觉输入。浦肯野样细胞在其细胞体附近接收感觉输入。这些细胞将顶端树突延伸到分子层，在那里它们接收来自平行纤维的突触输入。小脑本身也可以被包括在这个特征中，因为它的攀爬纤维至少部分地是感觉信息的传送者，并且在更基底的脊椎动物中，攀爬纤维终止于靠近索马的光滑树突上。从三个不同的系统的生理研究结果表明，小脑样结构删除可预测的功能，从感觉流入的假设。系统发生同源性可以解释某些类型小脑样结构在不同分类群之间的相似性，但其他类型的相似性不能以这种方式解释。此外，系统发育同源性不能解释不同类型小脑样结构之间的相似性。进化趋同为所有这些不能用同源性来解释的相似性提供了最好的解释。几乎可以肯定的是，这种趋同性受到两个因素的限制：一是创造类似小脑的电路的遗传发育程序的可用性，二是许多不同系统都需要类似小脑的电路所能提供的信息处理类型。版权所有（C）2002 S. Karger AG，巴塞尔。
All vertebrate brains have a cerebellum, and most of them have one or more additional structures that are histologically similar to the cerebellum. The cerebellum-like structures include the medial octavolateral nucleus in most aquatic vertebrates; the dorsal octavolateral nucleus in many aquatic vertebrates with an electrosensory system; the marginal layer of the optic tectum in ray-finned fishes; electrosensory lobes in the few groups of advanced bony fish with an electrosensory system; the rostrolateral nucleus of the thalamus in a few widely scattered groups of bony fish; and the dorsal cochlear nucleus in all mammals except monotremes. All of these structures receive topographically organized sensory input in their deep layers. Purkinje-like cells receive the sensory input near their cell bodies. These cells extend apical dendrites up into the molecular layer where they receive synaptic input from parallel fibers. The cerebellum itself can be included within this characterization by considering the climbing fiber as at least in part a conveyor of sensory information and by recalling that climbing fibers in more basal vertebrates terminate on smooth dendrites close to the soma. Physiological findings from three different systems suggest the hypothesis that cerebellum-like structures remove predictable features from the sensory inflow. Phylogenetic homology can explain the similarities across different taxa for some types of cerebellum-like structures, but similarities within other types cannot be explained in this way. Moreover, phylogenetic homology cannot explain the similarities among different types of cerebellum-like structures. Evolutionary convergence provides the best explanation for all these similarities that cannot be explained by homology. The convergence is almost surely constrained by the availability of a genetic-developmental program for creating cerebellum-like circuitry and by the need within many different systems for the type of information processing that cerebellum-like circuitry can provide. Copyright (C) 2002 S. Karger AG, Basel.