Lund J S, Hawken M J, Parker A J
Department of Psychiatry, University of Pittsburgh, Pennsylvania 15261.
J Comp Neurol. 1988 Oct 1;276(1):1-29. doi: 10.1002/cne.902760102.
This study investigates the intrinsic organization of axons and dendrites of aspinous, local circuit neurons of the macaque monkey visual striate cortex. These investigations use Golgi Rapid preparations of cortical tissue from monkey aged 3 weeks postnatal to adult. We have earlier (Lund, '87) described local circuit neurons found within laminae 5A and 4C; this present account is of neurons found in the infragranular laminae 5B and 6. Since the majority of such neurons are GABAergic and therefore believed to be inhibitory, their role in laminae 5B and 6, the principal sources of efferent projections to subcortical regions, is of considerable importance. We find laminae 5B and 6 to have in common at least one general class of local circuit neuron-the "basket" neuron. However, a major difference is seen in the axonal projections to the superficial layers made by these and other local circuit neurons in the two laminae; lamina 5B has local circuit neurons with principal rising axon projections to lamina 2/3A, areas whereas lamina 6 has local circuit neurons with principal rising axon projections to divisions of 4C, 4A, and 3B. These local circuit neuron axon projections mimic the different patterns of apical dendritic and recurrent axon projections of pyramidal neurons lying within laminae 5B and 6, which are linked together by both dendritic and axonal arbors of local circuit neurons in their neuropils extending between the two laminae. The border zone between 5B and 6 is a specialized region with its own variety of horizontally oriented local circuit neurons, and it also serves as a special focus for pericellular axon arrays from a particular variety of local circuit neuron lying within lamina 6. These pericellular axon "baskets" surround the somata and initial dendritic segments of the largest pyramidal neurons of layer 6, which are known to project both to cortical area MT (V5) and to the superior colliculus (Fries et al., '85). Many of the local circuit neurons of layer 5B send axon trunks into the white matter, and we therefore, suspect them of providing efferent projections. The axons of lamina 6 local circuit neurons have not been found to make such clear-cut contributions to the white matter.
本研究调查了猕猴视纹状皮层无棘局部回路神经元轴突和树突的内在组织。这些研究使用了出生后3周龄至成年猴子的皮质组织的高尔基快速染色标本。我们之前（伦德，1987年）描述了在5A层和4C层中发现的局部回路神经元；本报告是关于在颗粒下层5B层和6层中发现的神经元。由于这类神经元中的大多数是γ-氨基丁酸能的，因此被认为具有抑制作用，它们在5B层和6层（向皮质下区域发出传出投射的主要来源）中的作用相当重要。我们发现5B层和6层至少有一类共同的局部回路神经元——“篮状”神经元。然而，这两层中这些和其他局部回路神经元向表层的轴突投射存在一个主要差异；5B层的局部回路神经元主要有上升的轴突投射到2/3A层区域，而6层的局部回路神经元主要有上升的轴突投射到4C、4A和3B层的分区。这些局部回路神经元的轴突投射模仿了位于5B层和6层的锥体细胞的顶树突和回返轴突投射的不同模式，它们通过局部回路神经元在两层之间延伸的神经毡中的树突和轴突分支连接在一起。5B层和6层之间的边界区域是一个特殊区域，有其自身各种水平方向的局部回路神经元，并且它也是来自6层中一种特定类型局部回路神经元的细胞周轴突阵列的特殊聚焦点。这些细胞周轴突“篮”围绕着6层最大锥体细胞的胞体和初始树突段，已知这些锥体细胞既投射到皮质区域MT（V5），也投射到上丘（弗里斯等人，1985年）。5B层的许多局部回路神经元将轴突主干送入白质，因此，我们怀疑它们提供传出投射。尚未发现6层局部回路神经元的轴突对白质有如此明确的贡献。
