Kisvarday Z F, Martin K A, Friedlander M J, Somogyi P
J Comp Neurol. 1987 Jun 1;260(1):1-19. doi: 10.1002/cne.902600102.
An interlaminar, ascending, and GABAergic projection is demonstrated in the striate cortex of the cat. We have examined a basket cell, with soma and smooth dendrites in layers V and VI, that was injected intracellularly with HRP in the kitten. Three-dimensional reconstruction of its axon revealed a horizontal plexus in layer V and upper VI, extending about 1.8 mm anteroposteriorly and 0.8 mm mediolaterally; a dense termination in the vicinity of the soma in layers V and VI; and an ascending tuft terminating in layers II and III in register above the soma and about 250 microns in diameter. Many boutons of this cell contacted neuronal somata and apical dendrites of pyramidal cells and subsequent electron microscopy showed that these boutons formed type II synaptic contacts with these structures. A random sample of postsynaptic targets (n = 199) in layers III, V, and VI showed that somata (20.1%), dendritic shafts (38.2%), and dendritic spines (41.2%) were contacted. The fine structural characteristics of postsynaptic elements indicated that the majority originated from pyramidal cells. Direct identification of postsynaptic neurons was achieved by Golgi impregnation of four large pyramidal cells in layer V, which were contacted on their somata and apical dendrites by between three and 34 boutons of the HRP-filled basket cell. Layer IV neurons were not contacted. Golgi-impregnated neurons similar to the HRP-filled basket cell were also found in the deep layers. The axonal boutons of one of them were studied; it also formed type II synapses with somata and apical dendrites of pyramidal cells. Boutons of the HRP-filled neuron were shown to be GABA-immunoreactive by the immunogold method. This is direct evidence in favour of the GABAergic nature of deep layer basket cells with ascending projections. The existence of an ascending GABAergic pathway was also demonstrated by injecting [3H]GABA into layers II and III. The labelled amino acid was transported retrogradely by a subpopulation of GABA-immunoreactive cells in layers V and VI, in addition to cells around the injection site. The axonal pattern and mode of termination of deep basket cells make them a candidate for producing or enhancing directional selectivity, a characteristic of layer V cells.(ABSTRACT TRUNCATED AT 400 WORDS)
在猫的纹状皮质中发现了一种层间、上行且为γ-氨基丁酸（GABA）能的投射。我们研究了一只小猫体内的一个篮状细胞，其胞体和光滑的树突位于V层和VI层，对其进行了细胞内辣根过氧化物酶（HRP）注射。对其轴突的三维重建显示，在V层和VI层上部有一个水平神经丛，前后延伸约1.8毫米，内外侧延伸约0.8毫米；在V层和VI层胞体附近有密集的终末；还有一个上行的簇状终末，终止于胞体上方的II层和III层，直径约250微米。该细胞的许多终扣与神经元胞体以及锥体细胞的顶端树突相接触，随后的电子显微镜观察表明，这些终扣与这些结构形成了II型突触联系。对III层、V层和VI层中随机抽取的突触后靶点（n = 199）进行观察发现，胞体（20.1%）、树突干（38.2%）和树突棘（41.2%）都有被接触。突触后成分的精细结构特征表明，大多数起源于锥体细胞。通过对V层的四个大型锥体细胞进行高尔基染色，直接鉴定出了突触后神经元，这些锥体细胞的胞体和顶端树突被填充HRP的篮状细胞的3至34个终扣所接触。IV层神经元未被接触。在深层中也发现了与填充HRP的篮状细胞相似的高尔基染色神经元。对其中一个神经元的轴突终扣进行了研究；它也与锥体细胞的胞体和顶端树突形成了II型突触。通过免疫金法显示，填充HRP的神经元的终扣具有GABA免疫反应性。这是支持具有上行投射的深层篮状细胞为GABA能性质的直接证据。通过向II层和III层注射[3H]GABA，也证明了上行GABA能通路的存在。除了注射部位周围的细胞外，标记的氨基酸还被V层和VI层中一群GABA免疫反应性细胞逆行转运。深层篮状细胞的轴突模式和终末方式使其成为产生或增强方向选择性的候选细胞，方向选择性是V层细胞的一个特征。（摘要截取自400字）
