An electron microscopic study of the laminar pattern and mode of termination of afferent fibre pathways in the somatic sensory cortex of the cat.
An electron microscopic study of the laminar pattern and mode of termination of afferent fibre pathways in the somatic sensory cortex of the cat.
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猫躯体感觉皮层传入纤维通路的层状模式和终止模式的电子显微镜研究。
DOI：
10.1098/rstb.1970.0007
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发表时间：
1970
期刊：
影响因子：
--
通讯作者：
T. Powell
中科院分区：
文献类型：
--
作者：
E. Jones;T. Powell
在一系列实验中，选择性地中断了通往躯体感觉区的外源性传入通路，并研究了每隔2~6天变性突触末梢的分布和终止方式。退化的连合纤维终止于各皮质层中、小树突上的棘突上，但终末主要集中在第I、III层和第IV层的深层。从SII传递到SI的皮质联合纤维末端主要在皮质的中间层(III、IV和V)的中小型树突的棘上，但在分子层中总是可见少量。后者中的一些可能来自细小的有髓轴突，这些轴突从病变径向扩散，恰好在软脑膜下方运行。变性的丘脑皮质轴突终止于棘突上，少数终止于直径较小的树突干上，主要在第IV层，但与第III层和第V层的相邻部分重叠，另外有少量但一致的数目终止于分子层。因此，分子层和第四层接受所有外部传入的终止，而这些与其他层的关系和它们的终止方式在每种情况下都略有不同。对这一结果的一种解释是，所有三组外源性传入都终止于锥体神经元顶树的中段，丘脑皮质纤维在星状神经元上有额外的终末。讨论了这一安排的功能含义。
In a series of experiments, the extrinsic afferent pathways to the somatic sensory areas have been selectively interrupted and the distribution and mode of termination of degenerating synaptic endings studied at intervals of 2 to 6 days. Degenerating commissural fibres terminate on spines attached to dendrites of medium and small size in all cortical layers, but the endings are concentrated in the deeper parts of layers I and III and in layer IV. Cortical association fibres passing from SII to SI end on spines of small and medium-sized dendrites mainly in the intermediate layers (III, IV and V) of the cortex, but a small number are invariably seen in the molecular layer. Some of the latter are probably derived from thin myelinated axons which spread radially from a lesion and run just beneath the pia mater. Degenerating thalamo-cortical axons terminate on spines and to a lesser extent on shafts of dendrites of small diameter, mainly in layer IV but with overlap into adjacent parts of layers III and V and with an additional small but consistent number ending in the molecular layer. Thus, the molecular layer and layer IV receive the terminations of all extrinsic afferents, while the relations of these to the other laminae and their mode of termination is, in each case, slightly different. One interpretation of the results is that all three sets of extrinsic afferents terminate in the middle portion of the apical dendritic tree of pyramidal neurons, and that thalamo-cortical fibres have additional terminals on stellate neurons. The functional implications of this arrangement are discussed.