Contributions of individual layer 2-5 spiny neurons to local circuits in macaque primary visual cortex
Contributions of individual layer 2-5 spiny neurons to local circuits in macaque primary visual cortex
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DOI：
10.1017/s0952523800009159
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发表时间：
1996-09-01
影响因子：
1.9
通讯作者：
Wiser, AK
中科院分区：
文献类型：
--
作者：
Callaway, EM;Wiser, AK
我们研究了猕猴初级视皮层(V1)的兴奋性局部环路，以探讨它们与大细胞(M)和小细胞(P)流的关系。对2~5层62个细胞内标记的棘神经元进行了分析。我们对轴突的层状和柱状的特异性进行了详细的观察，并注意到与树枝的相关性。我们发现有证据表明，V1中的本地电路相当程度上混合了M和P流。这种混合是由初级膝状受体层4C中的神经元以及颗粒上和颗粒下层的神经元提供的。我们还对具有不同树突形态的神经元的轴突投射可能存在的差异感兴趣。我们发现，4B层棘状星状神经元和锥体神经元具有相似的轴突。然而，我们发现了两种类型的第5层锥体神经元。大多数具有传统的锥体树突形态，在第2-4B层有致密的轴突，不投射到白质。第5层投射神经元具有不寻常的“反向分支”树突形态(顶端树突分支向下而不是向上)，在第2-4B层有弱的或没有轴突树枝，但在5B层有较长的水平轴突投射。我们没有发现从第5层锥体神经元到第6层的强烈投射。在猕猴V1中，似乎没有单一的强局部输入到第6层；只有第2-5层的少数细胞在第6层有轴突分支，这些轴突是稀疏的。我们的结果表明，V1中的局部回路调节了M和P输入之间的相互作用，这些相互作用是复杂的，不容易合并到一个简单的框架中。
We studied excitatory local circuits in the macaque primary visual cortex (V1) to investigate their relationships to the magnocellular (M) and parvocellular (P) streams. Sixty-two intracellularly labeled spiny neurons in layers 2-5 were analyzed. We made detailed observations of the laminar and columnar specificity of axonal arbors and noted correlations with dendritic arbors. We find evidence for considerable mixing of M and P streams by the local circuitry in V1. Such mixing is provided by neurons in the primary geniculate recipient layer 4C, as well as by neurons in both the supragranular and infragranular layers. We were also interested in possible differences in the axonal projections of neurons with different dendritic morphologies. We found that layer 4B spiny stellate and pyramidal neurons have similar axonal arbors. However, we identified two types of layer 5 pyramidal neuron. The majority have a conventional pyramidal dendritic morphology, a dense axonal arbor in layers 2-4B, and do not project to the white matter. Layer 5 projection neurons have an unusual ''backbranching'' dendritic morphology (apical dendritic branches are downward rather than upward) and weak or no axonal arborization in layers 2-4B, but have long horizontal axonal projections in layer 5B. We find no strong projection from layer 5 pyramidal neurons to layer 6. In macaque V1 there appears to be no single source of strong local input to layer 6; only a minority of cells in layers 2-5 have axonal branches in layer 6 and these are sparse. Our results suggest that local circuits in V1 mediate interactions between M and P input that are complex and not easily incorporated into a simple framework.