Total number and distribution of inhibitory and excitatory synapses on hippocampal CA1 pyramidal cells
Total number and distribution of inhibitory and excitatory synapses on hippocampal CA1 pyramidal cells
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DOI：
10.1016/s0306-4522(00)00496-6
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发表时间：
2001-01-01
期刊：
影响因子：
3.3
通讯作者：
Gulyás, AI
中科院分区：
文献类型：
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作者：
Megías, M;Emri, Z;Gulyás, AI
神经元的整合特性强烈依赖于它们接收的兴奋性和抑制性突触输入的数量、比例和分布。本研究通过测量大鼠海马CA1区锥体细胞树突树的三维几何形状和不同细胞室的对称性和非对称性突触密度来计算单个细胞上兴奋性和抑制性输入的总数和分布。单个锥体细胞具有类似于12000个神经元的树突，接受大约30000个兴奋性和1700个抑制性输入，其中40%集中在腔隙分子层的树突上，40%集中在腔隙分子层的树突上。突触前和突触后的特征提示CA1锥体细胞树突是异质性的。放射状地层和东方树枝状结构既相似又不同于孔洞-分子树状结构。近端顶层和基底层放射状，东方树突无刺或疏生刺状。远端的放射状和东方层的树突(占锥体细胞树的68.5%)是密集刺状的；它们的兴奋性输入仅终止于树突棘，而抑制性输入仅针对树突轴。远端棘状地层、放射状地层和东方树突的抑制输入比例很低(接近3%)。相反，近端的树突节段大部分(70%-100%)接受抑制性输入。只有抑制性输入支配躯体(每个细胞77-103个)和轴突起始节段。腔隙分子层中的树突具有中到少量的刺。兴奋性突触：腔隙分子层上的树突比其他层的突触大，常穿孔(约占40%)，可位于树突干上。我们的结果表明：(I)到达锥体细胞远端树突的高度会聚的兴奋主要由近端的抑制所控制；(Ii)在接受Schaffer侧支输入(放射体/东方)和贯通通路输入(腔隙-分子)的各层中，兴奋性和抑制性输入的组织结构明显不同。(C)2001年IBRO。爱思唯尔科学有限公司出版。版权所有。
The integrative properties of neurons depend strongly on the number, proportions and distribution of excitatory and inhibitory synaptic inputs they receive. In this study the three-dimensional geometry of dendritic trees and the density of symmetrical and asymmetrical synapses on different cellular compartments of rat hippocampal CA1 area pyramidal cells was measured to calculate the total number and distribution of excitatory and inhibitory inputs on a single cell.A single pyramidal cell has similar to 12,000 mum dendrites and receives around 30,000 excitatory and 1700 inhibitory inputs, of which 40% are concentrated in the perisomatic region and 20% on dendrites in the stratum lacunosum-moleculare. The pre and post-synaptic features suggest that CA 1 pyramidal cell dendrites are heterogeneous. Strata radiatum and oriens dendrites are similar and differ from stratum lacunosum-moleculare dendrites. Proximal apical and basal strata radiatum and oriens dendrites are spine-free or sparsely spiny. Distal strata radiatum and oriens dendrites (forming 68.5% of the pyramidal cells ' dendrite tree) are densely spiny; their excitatory inputs terminate exclusively on dendritic spines, while inhibitory inputs target only dendritic shafts. The proportion of inhibitory inputs on distal spiny strata radiatum and oriens dendrites is low (similar to3%). In contrast, proximal dendritic segments receive mostly (70-100%) inhibitory inputs. Only inhibitory inputs innervate the somata (77-103 per cell) and axon initial segments. Dendrites in the stratum lacunosum-moleculare possess moderate to small amounts of spines. Excitatory synapses: on stratum lacunosum-moleculare dendrites are larger than the synapses in other layers, are frequently perforated (similar to 40%) and can be located on dendritic shafts. Inhibitory inputs, whose percentage is relatively high (similar to 14-17%), also terminate on dendritic spines.Our results indicate that: (i) the highly convergent excitation arriving onto the distal dendrites of pyramidal cells is primarily controlled by proximally located inhibition; (ii) the organization of excitatory and inhibitory inputs in layers receiving Schaffer collateral input (radiatum/oriens) versus perforant path input (lacunosum-moleculare) is significantly different. (C) 2001 IBRO. Published by Elsevier Science Ltd. All rights reserved.