Local potential connectivity in cat primary visual cortex
Local potential connectivity in cat primary visual cortex
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DOI：
10.1093/cercor/bhm027
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发表时间：
2008-01-01
期刊：
影响因子：
3.7
通讯作者：
Chklovskii, Dmitri B.
中科院分区：
文献类型：
--
作者：
Stepanyants, Armen;Hirsch, Judith A.;Chklovskii, Dmitri B.
皮层回路中突触连接的时不变描述可能被伴随突触形成和消除的树突棘的持续生长和收缩所排除。另一方面，轴突和树枝的空间排列似乎稳定。这表明，连接性的不变描述可以用潜在的突触来描述，突触是神经元中一个神经元的轴突分支接近另一个神经元的树突分支的位置。在本文中，我们试图重建猫初级视觉皮质（V1）局部皮质回路的潜在连接性。基于多个单神经元重建的轴突和树突的乔木在3个维度，我们评估的预期数量的潜在突触和潜在的兴奋性（锥体和棘星状）神经元和抑制性篮细胞之间的连接的概率。结果提供了一个定量描述的局部皮层电路的结构组织。对于来自不同皮层层的兴奋性神经元，我们计算局部域，其中包含它们潜在的突触前和突触后兴奋性伙伴。这些域具有层状特定半径的柱状形状，并且大致为眼优势柱的大小。因此，眼优势柱中大多数兴奋性神经元之间的连接可以通过局部突触发生来实现。抑制性篮状细胞的结构连接通常比兴奋性连接弱。在这里，只有附近的神经元能够建立一个以上的潜在突触，这意味着在眼优势柱内，这些连接具有更有限的电路重塑潜力。
Time invariant description of synaptic connectivity in cortical circuits may be precluded by the ongoing growth and retraction of dendritic spines accompanied by the formation and elimination of synapses. On the other hand, the spatial arrangement of axonal and dendritic branches appears stable. This suggests that an invariant description of connectivity can be cast in terms of potential synapses, which are locations in the neuropil where an axon branch of one neuron is proximal to a dendritic branch of another neuron. In this paper, we attempt to reconstruct the potential connectivity in local cortical circuits of the cat primary visual cortex (V1). Based on multiple single-neuron reconstructions of axonal and dendritic arbors in 3 dimensions, we evaluate the expected number of potential synapses and the probability of potential connectivity among excitatory (pyramidal and spiny stellate) neurons and inhibitory basket cells. The results provide a quantitative description of structural organization of local cortical circuits. For excitatory neurons from different cortical layers, we compute local domains, which contain their potentially pre- and postsynaptic excitatory partners. These domains have columnar shapes with laminar specific radii and are roughly of the size of the ocular dominance column. Therefore, connections between most excitatory neurons in the ocular dominance column can be implemented by local synaptogenesis. Structural connectivity involving inhibitory basket cells is generally weaker than excitatory connectivity. Here, only nearby neurons are capable of establishing more than one potential synapse, implying that within the ocular dominance column these connections have more limited potential for circuit remodeling.