Woolf T B, Shepherd G M, Greer C A
Section of Neurobiology, Yale University School of Medicine, New Haven, Connecticut 06510.
J Neurosci. 1991 Jun;11(6):1837-54. doi: 10.1523/JNEUROSCI.11-06-01837.1991.
The anaxonic granule cell of the olfactory bulb is believed to inhibit mitral and tufted cells through reciprocal dendrodendritic synapses. However, little is known about the detailed input-output properties of the granule cell. This study explores the functional properties of granule cells by using detailed reconstructions of Golgi-impregnated granule cells as the basis for computational models. Three Golgi-impregnated granule cells from the olfactory bulbs of C57BL/6j mice were selected for detailed analysis. Measurements were made of the diameter and length of all spine heads, spine necks, and dendritic branches. These measurements formed the basis of a compartmental model of each cell in which simulations of the spread of synaptic potentials within the dendritic tree were performed with SABER (Analogy, Inc.), a circuit analysis program. The results show that the degree of spread of synaptic potentials can define functionally related subsets of spines within the dendritic tree. The size of these subsets varies with the anatomical location of the input spine, the magnitude of the input, the time course of the input, the size of the spine neck resistance, and the activity of other spines. The data indicate that the functional organization of granule cell dendritic arbors is more complex than previously thought: between the level of the individual spine and the entire dendritic tree are several levels of subsets of spines that can mediate discrete localized inhibition onto subsets of mitral or tufted cell secondary dendrites within the external plexiform layer of the olfactory bulb.
嗅球的无轴突颗粒细胞被认为通过相互的树突-树突突触抑制二尖瓣细胞和簇状细胞。然而，关于颗粒细胞详细的输入-输出特性却知之甚少。本研究以高尔基浸染的颗粒细胞的详细重建为计算模型的基础，探索颗粒细胞的功能特性。从C57BL/6j小鼠的嗅球中选取了三个高尔基浸染的颗粒细胞进行详细分析。对所有棘突头部、棘突颈部和树突分支的直径和长度进行了测量。这些测量结果构成了每个细胞的房室模型的基础，在该模型中，使用电路分析程序SABER（Analogy公司）对树突状树内突触电位的传播进行了模拟。结果表明，突触电位的传播程度可以定义树突状树内功能相关的棘突子集。这些子集的大小随输入棘突的解剖位置、输入的大小、输入的时间进程、棘突颈部电阻的大小以及其他棘突的活动而变化。数据表明，颗粒细胞树突状分支的功能组织比以前认为的更为复杂：在单个棘突水平和整个树突状树之间，存在几个棘突子集水平，它们可以介导对嗅球外丛状层内二尖瓣或簇状细胞二级树突子集的离散局部抑制。
