大鼠扣带皮质V层锥体细胞的电生理学和形态学特征的研究

THE ELECTROPHYSIOLOGICAL PROPERTIES AND MORPHOLOGICAL CHARACTERISTICS OF THE PYRAMIDAL CELLS IN THE LAYER V OF THE CINGULATE CORTEX IN THE RAT

本文用细胞内记录、Ｂｉｏｃｙｔｉｎ注入和细胞内染色相结合的方法，在大鼠离体脑片上，对扣带皮质Ｖ层锥体细胞的基本电生理学特性和形态学特征进行了研究．注入Ｂｉｏｃｒｔｉｎ的锥体细胞位于扣带皮质１区（Ｃｓｌ区）和２区（Ｃｇ２区），Ｃｇ１区和Ｃｇ２区性体细胞的电生理学特性不同，特别是后电位有差异。Ｃｇ１区锥体细胞的锋电位出现后有显著的快速后超极化跟随；Ｃｇ２区神经元的快速后超极化较小，但出现中等范围后超极化和会极化后电位。两区锥体细胞在形态学特征上也存在差异，Ｃｇ１区锥体细胞的顶树突比Ｃｇ２区者长，且在皮质浅层内分支较少；而Ｃｇ２区锥体细胞的顶树突则有较多分支。Ｃｇ２区锥体细胞的基树突比Ｃｇ１区神经元者延伸范围广且密集。所有的锥体细胞都有一条伸入皮质下白质的主轴突，Ｃｇ１区神经元的轴突侧支主要沿顶树突在垂直方向上分布，而Ｃｇ２区神经元的轴突侧支则延伸至较广泛的区域．

The basic electrical properties and morphological characteristics of the pyramidal cells in layer V of the cingulate cortexwere examined by a combined method of intracellular recording, Biocytin injection, and intracellular staining using in vitroslice preparations of the rat brain. The results showed that Biocytin-injected pyramidal cells were located in the layer V ofthe area 1 and area 2 of the cingulate cortex (Cgl and CgZ). The Cgl and CgZ pyramidal cells showed differences in theirelectrical properties, especially in spike aftetpotentials. The pyramidal cells in Cgl displayed a larger fast afterhyperpolarization (fAHP), whereas CgZ neurons showed a smaller fAHP. Medium-range AHP (mAHP) and depolarizing afterpotential (DAP) were observed only in CgZ pyramidal cells. Thus, these Biocytin-labeled pyramidal cells were separated intotwo groups: Cgl pyramidal cell and CgZ pyramidal cell. These p,yramidal cells in those two areas also clearly exhibited morphological differences. The apical dendrites were longer in Cgl pyramidal cells than those in CgZ cells. The apical dendrite ofpyramidal cells in Cgl hardly branched within the superficial layers, but cells in CgZ had many arborizations. The hasal dendrites were more devdoped and denser in CgZ pyrsmidal cells than those in Cgl cells. The main a-cons of all the pyramidalcells entered the subcortical white matter. The axon collaterals of Cgl pyramidal cells were mainly distributed vertically along the apical dendrite, whereas those of CgZ cells were widely spread. The present results indicated that layer V pyramidalcells of the cingulate cortex might be separated into two groups, which were sup-ported not only by their electrical propertiesbut also by their morphological characteristics.