Institute of Neuroscience and Medicine, INM-10 Function of Cortical Microcircuits Group, Research Centre Jülich, 52425 Jülich, Germany.
Department of Biosystems Science and Engineering, ETH Zürich, Basel, Switzerland.
Cereb Cortex. 2021 Jan 1;31(1):32-47. doi: 10.1093/cercor/bhaa201.
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.
不同皮质区域的 GABA 能中间神经元在各种高级认知功能中发挥重要作用。不同感觉皮层中的中间神经元具有很好的异质性，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，基于轴突投射模式的聚类分析揭示了大鼠 mPFC 中的 L6 中间神经元有四个不同的簇：簇 1 中间神经元表现出类似于 Martinotti 样细胞的轴突投射，延伸到第 1 层；簇 2 显示出跨层投射，主要投射到第 5 层；簇 3 中间神经元的轴突局限于第 6 层，而簇 4 中间神经元的轴突也延伸到白质中。在所有簇中，神经元的位置与轴突分布之间存在相关性。此外，所有簇 1 的 L6 中间神经元均表现出具有初始高频爆发的单调适应放电模式。所有簇 2 的中间神经元均为快速放电，而簇 3 和 4 的神经元表现出异质的放电模式。我们的数据表明，具有不同形态和生理特征的 L6 中间神经元可能投射到 mPFC 的不同靶标，从而在 L6 微电路和 mPFC 相关功能中发挥不同的作用。
