Abstract

GABAergic interneurons in different cortical areas play important roles in diverse higher-order cognitive functions. The heterogeneity of interneurons is well characterized in different sensory cortices, in particular in primary somatosensory and visual cortex. However, the structural and functional properties of the medial prefrontal cortex (mPFC) interneurons have received less attention. In this study, a cluster analysis based on axonal projection patterns revealed four distinct clusters of L6 interneurons in rat mPFC: Cluster 1 interneurons showed axonal projections similar to Martinotti-like cells extending to layer 1, cluster 2 displayed translaminar projections mostly to layer 5, and cluster 3 interneuron axons were confined to the layer 6, whereas those of cluster 4 interneurons extend also into the white matter. Correlations were found between neuron location and axonal distribution in all clusters. Moreover, all cluster 1 L6 interneurons showed a monotonically adapting firing pattern with an initial high-frequency burst. All cluster 2 interneurons were fast-spiking, while neurons in cluster 3 and 4 showed heterogeneous firing patterns. Our data suggest that L6 interneurons that have distinct morphological and physiological characteristics are likely to innervate different targets in mPFC and thus play differential roles in the L6 microcircuitry and in mPFC-associated functions.

中文翻译：

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大鼠前额皮质第 6 层中间神经元的层特异性抑制微电路。

摘要

不同皮质区域的 GABA 能中间神经元在多种高阶认知功能中发挥着重要作用。中间神经元的异质性在不同的感觉皮层中得到了很好的表征，特别是在初级体感和视觉皮层中。然而，内侧前额叶皮层（mPFC）中间神经元的结构和功能特性受到的关注较少。在这项研究中，基于轴突投影模式的聚类分析揭示了大鼠 mPFC 中 L6 中间神经元的四个不同簇：簇 1 中间神经元显示类似于 Martinotti 样细胞的轴突投影，延伸至第 1 层，簇 2 显示主要延伸至第 5 层的跨层投影，第 3 簇中间神经元的轴突仅限于第 6 层，而第 4 簇中间神经元的轴突也延伸到白质中。所有簇中的神经元位置和轴突分布之间都存在相关性。此外，所有簇 1 L6 中间神经元都表现出单调适应的放电模式，并具有初始高频爆发。所有簇 2 中间神经元均快速放电，而簇 3 和簇 4 中的神经元则表现出异质放电模式。我们的数据表明，具有不同形态和生理特征的 L6 中间神经元可能支配 mPFC 中的不同靶点，从而在 L6 微电路和 mPFC 相关功能中发挥不同的作用。