Laminar and dorsoventral organization of layer 1 interneuronal microcircuitry in superficial layers of the medial entorhinal cortex

• Published in: Cell reports (Cambridge) 2023-07, Vol.42 (7), p.112782-112782, Article 112782
• Main Authors: Shi, Yuying, Cui, Hui, Li, Xiaoyue, Chen, Ligu, Zhang, Chen, Zhao, Xinran, Li, Xiaowan, Shao, Qiming, Sun, Qiang, Yan, Kaiyue, Wang, Guangfu
• Format: Article
• Language: English
• Subjects: connectivity matrix; CP: Cell biology; CP: Neuroscience; dorsoventral gradient; Electrophysiological Phenomena; Entorhinal Cortex - physiology; Interneurons - physiology; layer 1 interneurons; medial entorhinal cortex; morphological reconstruction; motif analysis; Neocortex; neurogliaform cells; neuronal cell-type classification; Neurons - physiology; simultaneous multiple whole-cell recordings; single bouquet-like cells
• ISSN: 2211-1247; 2211-1247
• DOI: 10.1016/j.celrep.2023.112782

Layer 1 (L1) interneurons (INs) participate in various brain functions by gating information flow in the neocortex, but their role in the medial entorhinal cortex (MEC) is still unknown, largely due to scant knowledge of MEC L1 microcircuitry. Using simultaneous triple-octuple whole-cell recordings and morphological reconstructions, we comprehensively depict L1IN networks in the MEC. We identify three morphologically distinct types of L1INs with characteristic electrophysiological properties. We dissect intra- and inter-laminar cell-type-specific microcircuits of L1INs, showing connectivity patterns different from those in the neocortex. Remarkably, motif analysis reveals transitive and clustered features of L1 networks, as well as over-represented trans-laminar motifs. Finally, we demonstrate the dorsoventral gradient of L1IN microcircuits, with dorsal L1 neurogliaform cells receiving fewer intra-laminar inputs but exerting more inhibition on L2 principal neurons. These results thus present a more comprehensive picture of L1IN microcircuitry, which is indispensable for deciphering the function of L1INs in the MEC. [Display omitted] •L1 interneurons of the MEC can be classified into three morphological types•Intra- and inter-laminar connectivity of L1 interneurons are cell-type specific•Higher-order motifs reveal non-random structured features of L1 networks•L1 interneuronal microcircuitry is differentially organized along the dorsoventral axis Using simultaneous triple-octuple whole-cell recordings, Shi et al. identify three morphological types of layer 1 interneurons in the medial entorhinal cortex, a critical brain area for spatial cognition. The authors comprehensively depict the intra- and inter-laminar networks of these interneurons, providing essential information for both behavior and modeling studies.