Akers R M, Killackey H P
J Comp Neurol. 1978 Oct 1;181(3):513-37. doi: 10.1002/cne.901810305.
An analysis based on Nissl, anterograde degeneration, and succinic dehydrogenase histochemical techniques reveals that there are two distinct regions of parietal cortex which are characterized by different cytoarchitectonic features and anatomical connections. The "granular" cortical zone possesses a well-defined fourth layer composed of small, densely-packed cells, receives dense projections from the ventral posterior nucleus of the thalamus, and is essentially free of callosal inputs. "Agranular" cortical areas which surround or lie embedded within the granular zone lack a well-defined fourth layer, receive sparse projection from the ventral posterior nucleus, but send and receive extensive callosal projections. These findings suggest that thalamic and callosal projections to the parietal cortex maintain a pattern of areal segregation. The granular cortical zone, which apparently corresponds to SmI, projects ipsilaterally to motor cortex, SmII, and adjacent agranular areas. The superficial layers of the granular cortex also project heavily upon the underlying layer V. This intracortical projection is not organized in discrete clusters within the "barrel field" cortex. This suggests that the specialized organization of thalamic afferents and granule cells within the "barrel field" is not maintained in the intracortical circuitry of this region.
基于尼氏染色、顺行性变性和琥珀酸脱氢酶组织化学技术的分析表明，顶叶皮层存在两个不同区域，其特征在于不同的细胞构筑特征和解剖学连接。“颗粒状”皮质区具有由小而密集排列的细胞组成的明确的第四层，接受来自丘脑腹后核的密集投射，并且基本上没有胼胝体输入。围绕或嵌入颗粒区的“无颗粒”皮质区域缺乏明确的第四层，接受来自腹后核的稀疏投射，但发送和接受广泛的胼胝体投射。这些发现表明，丘脑和胼胝体向顶叶皮层的投射保持区域分离模式。颗粒状皮质区显然对应于SmI，同侧投射到运动皮层、SmII和相邻的无颗粒区。颗粒状皮层的表层也大量投射到下层V。这种皮质内投射在“桶状区”皮层内不是以离散簇的形式组织的。这表明“桶状区”内丘脑传入纤维和颗粒细胞的特殊组织在该区域的皮质内回路中没有得到维持。
