Hersch S M, White E L
J Comp Neurol. 1981 Jan 10;195(2):253-63. doi: 10.1002/cne.901950206.
Synapses involving thalamocortical afferents and hitherto unexamined neuron types of the posteromedial barrel subfield (PMBSF) of the mouse have been identified using a combined degeneration and Golgi/EM technique (Peters et al., '77). Degeneration of thalamocortical axon terminals was produced with electrolytic lesions of the nucleus ventralis posterior, pars lateralis thalami, and the nucleus posterior thalami. Four days after receiving lesions, the animals were perfused, and blocks of cortex containing the PMBSF were processed by the Golgi method. The blocks were tissue-chopped at 125 microns and examined with the light microscope. Sections containing neurons of interest were gold-toned and deimpregnated in preparation for electron microscopy (Fairén et al., '77). Portions of selected neurons contained in layers III-IV were serially thin-sectioned and examined with an electron microscope to determine if they were involved in synapses with degenerating thalamocortical axon terminals. Results showed thalamocortical synapses on the apical dendrites of five different sized pyramidal cells whose somata occurred in layers V and VI, and on dendrites of on spiny bitufted neuron and one non-spiny multipolar neuron with somata in layer V. A non-spiny bitufted neuron of layer IV which was not impregnated also received thalamocortical synapses. Although every neuron examined formed at least one thalamocortical synapse, some formed very few, whereas others formed many. Of the pyramidal cells, small layer V and VI pyramidal cells and a large deep layer V pyramidal cell were involved in small numbers of thalamocortical synapses, while a medium superficial layer V pyramidal cell and a large layer VI pyramidal cell each formed many. The spiny bitufted neuron formed a small number of thalamocortical synapses. The findings suggest that, whereas any type of neuron with a dendrite in layer IV likely receives some synaptic input from the thalamus, individual neurons were involved in very different quantities of thalamocortical synapses.
利用联合变性法和高尔基/电子显微镜技术（彼得斯等人，1977年），已鉴定出涉及丘脑皮质传入神经以及小鼠后内侧桶状亚区（PMBSF）中迄今未经研究的神经元类型的突触。通过电解损伤丘脑腹后外侧核、丘脑外侧部和丘脑后核，造成丘脑皮质轴突终末的变性。在接受损伤四天后，对动物进行灌注，并用高尔基方法处理含有PMBSF的皮质块。将这些块切成125微米厚的组织切片，并用光学显微镜检查。含有感兴趣神经元的切片进行镀金黄和脱浸处理，以准备进行电子显微镜检查（法伦等人，1977年）。对位于III - IV层的选定神经元的部分进行连续超薄切片，并用电镜检查，以确定它们是否与变性的丘脑皮质轴突终末形成突触。结果显示，在五个不同大小的锥体细胞的顶端树突上有丘脑皮质突触，这些锥体细胞的胞体位于V层和VI层，在一个棘状双簇神经元的树突上以及一个胞体位于V层的无棘多极神经元的树突上也有丘脑皮质突触。IV层中一个未被浸染的无棘双簇神经元也接受丘脑皮质突触。尽管检查的每个神经元至少形成一个丘脑皮质突触，但有些形成的很少，而有些则形成很多。在锥体细胞中，V层和VI层的小锥体细胞以及V层深部的一个大锥体细胞参与的丘脑皮质突触数量较少，而V层中部的一个中锥体细胞和VI层的一个大锥体细胞各自形成了许多突触。棘状双簇神经元形成的丘脑皮质突触数量较少。这些发现表明，虽然IV层中任何带有树突的神经元类型可能都从丘脑接受一些突触输入，但单个神经元参与的丘脑皮质突触数量差异很大。
