Fitted parameters of the simplified models.

GABAergic inhibitory neurons fundamentally shape the activity and plasticity of cortical circuits. A major subset of these neurons contains somatostatin (SOM); these cells play crucial roles in neuroplasticity, learning, and memory in many brain areas including the hippocampus, and are implicated in several neuropsychiatric diseases and neurodegenerative disorders. Two main types of SOM-containing cells in area CA1 of the hippocampus are oriens-lacunosum-moleculare (OLM) cells and hippocampo-septal (HS) cells. These cell types show many similarities in their soma-dendritic architecture, but they have different axonal targets, display different activity patterns in vivo, and are thought to have distinct network functions. However, a complete understanding of the functional roles of these interneurons requires a precise description of their intrinsic computational properties and their synaptic interactions. In the current study we generated, analyzed, and make available several key data sets that enable a quantitative comparison of various anatomical and physiological properties of OLM and HS cells in mouse. The data set includes detailed scanning electron microscopy (SEM)-based 3D reconstructions of OLM and HS cells along with their excitatory and inhibitory synaptic inputs. Combining this core data set with other anatomical data, patch-clamp electrophysiology, and compartmental modeling, we examined the precise morphological structure, inputs, outputs, and basic physiological properties of these cells. Our results highlight key differences between OLM and HS cells, particularly regarding the density and distribution of their synaptic inputs and mitochondria. For example, we estimated that an OLM cell receives about 8,400, whereas an HS cell about 15,600 synaptic inputs, about 16% of which are GABAergic. Our data and models provide insight into the possible basis of the different functionality of OLM and HS cell types and supply essential information for more detailed functional models of these neurons and the hippocampal network.

γ-氨基丁酸能抑制性神经元（GABAergic inhibitory neurons）从根本上塑造大脑皮层环路的活动与可塑性。这类神经元的一个主要亚群表达生长抑素（somatostatin, SOM）；这些细胞在包括海马体在内的多个脑区的神经可塑性、学习与记忆过程中发挥关键作用，并与多种神经精神疾病及神经退行性病症密切相关。

海马CA1区中存在两类主要的含生长抑素细胞，即原层-腔隙层-分子层（OLM）细胞与海马-隔核（HS）细胞。这两类细胞在胞体-树突结构上存在诸多相似之处，但轴突投射靶点各不相同，活体中的活动模式也存在差异，被认为具有独特的网络功能。

然而，要全面阐明这些中间神经元的功能角色，需精准描述其内在计算特性与突触相互作用。本研究中，我们生成、分析并公开了多组关键数据集，可用于定量比较小鼠OLM细胞与HS细胞的多项解剖学与生理学特性。该数据集包含基于扫描电子显微镜（SEM）的OLM细胞与HS细胞及其兴奋性、抑制性突触输入的精细三维重建结果。

结合该核心数据集与其他解剖学数据、膜片钳电生理学数据及隔室建模结果，我们对这些细胞的精确形态结构、输入输出模式与基本生理特性开展了研究。研究结果揭示了OLM细胞与HS细胞之间的关键差异，尤其是在突触输入与线粒体的密度及分布方面。例如，我们估算得到OLM细胞接收约8400个突触输入，而HS细胞约接收15600个，其中约16%为γ-氨基丁酸能突触输入。

本研究的数据与模型为理解OLM细胞与HS细胞的功能差异提供了潜在依据，并为这类神经元及海马环路的更精细功能模型提供了关键信息。