Yamamoto T, Samejima A, Oka H
Department of Physiology, Fukui Medical School, Japan.
J Comp Neurol. 1987 Nov 15;265(3):380-90. doi: 10.1002/cne.902650307.
Layer V pyramidal neurons in the cat parietal cortex (areas 5 and 7) were investigated with intracellular HRP staining. Antidromic responses were recorded intracellularly as well as extracellularly with pontine stimulation under Nembutal anesthesia. The relationship between the latency of antidromic responses and the morphology of HRP-stained neurons was analyzed. A total of 65 neurons were stained with HRP, and sixteen of these neurons were activated antidromically with pontine stimulation. Two distinct groups of layer V pyramidal neurons were detected morphologically by intracellular HRP staining; i.e., one (F type) consisted of neurons with relatively large somata (58.4 +/- 8.1 micron X 24.5 +/- 5.1 micron, N = 11) and aspiny or sparsely spinous apical dendrites, and the other (S type) consisted of neurons with smaller somata (44.6 +/- 7.6 micron X 19.3 +/- 3.9 micron, N = 22) and richly spinous apical dendrites. These two groups showed different electrophysiological properties; i.e., the former responded antidromically to pontine stimulation at a latency shorter than 1.5 ms (namely, with a conduction velocity faster than 18 m/second) and the latter responded at a latency longer than 1.5 ms. The two neuronal types in the parietal cortex corresponded respectively to fast and slow pyramidal tract neurons (PTNs) investigated in the sensorimotor cortex. Although their morphological features were almost similar to those of PTNs, the branching pattern of apical dendrites of the F-type pyramidal neuron seemed to be different from that of fast PTNs. In the parietal cortex, apical dendrites of F-type neurons showed rather frequent branching in layer I. This was similar to the pattern of branching in slow PTNs. Such a characteristic branching pattern suggested that, in the cat parietal cortex, layer V pyramidal neurons of both types are adapted to receive cerebellar inputs through the ventroanterior (VA) thalamic nucleus to the superficial cortical layers.
采用细胞内辣根过氧化物酶（HRP）染色法对猫顶叶皮质（5区和7区）的V层锥体神经元进行了研究。在戊巴比妥麻醉下，通过脑桥刺激，细胞内和细胞外记录了逆向反应。分析了逆向反应潜伏期与HRP染色神经元形态之间的关系。共有65个神经元被HRP染色，其中16个神经元在脑桥刺激下被逆向激活。通过细胞内HRP染色在形态学上检测到V层锥体神经元有两种不同的类型；即一种（F型）由胞体相对较大（58.4±8.1微米×24.5±5.1微米，N = 11）且顶树突无棘或棘少的神经元组成，另一种（S型）由胞体较小（44.6±7.6微米×19.3±3.9微米，N = 22）且顶树突有丰富棘的神经元组成。这两组显示出不同的电生理特性；即前者对脑桥刺激的逆向反应潜伏期短于1.5毫秒（即传导速度快于18米/秒），而后者的反应潜伏期长于1.5毫秒。顶叶皮质中的这两种神经元类型分别对应于在感觉运动皮质中研究的快和慢锥体束神经元（PTN）。尽管它们的形态特征与PTN几乎相似，但F型锥体神经元顶树突的分支模式似乎与快PTN不同。在顶叶皮质中，F型神经元的顶树突在I层的分支相当频繁。这与慢PTN的分支模式相似。这种特征性的分支模式表明，在猫顶叶皮质中，两种类型的V层锥体神经元都适合通过腹前（VA）丘脑核接收小脑输入至皮质浅层。
