Parvalbumin Interneurons Are Differentially Connected to Principal Cells in Inhibitory Feedback Microcircuits along the Dorsoventral Axis of the Medial Entorhinal Cortex
Parvalbumin Interneurons Are Differentially Connected to Principal Cells in Inhibitory Feedback Microcircuits along the Dorsoventral Axis of the Medial Entorhinal Cortex
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DOI：
10.1523/eneuro.0354-20.2020
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发表时间：
2021-01-01
期刊：
影响因子：
3.4
通讯作者：
Vida, Imre
中科院分区：
文献类型：
--
作者：
Grosser, Sabine;Barreda, Federico J.;Vida, Imre
内侧内嗅皮层（mEC）表现出高度的空间调谐，主要是网格细胞活动，这依赖于局部中间神经元（INs）提供的强大的动态抑制。事实上，反馈抑制微电路涉及快速尖峰小白蛋白篮细胞（BCs），被认为是主细胞（PrCs）中网格细胞放电的主要原因。然而，PV - bc介导的对prc的抑制强度在该区域并不均匀，但在背侧mEC高，而在腹侧mEC弱。这与不同的网格场大小有很好的相关性，但潜在的形态和生理机制尚不清楚。在这项研究中，我们检测了幼年大鼠mEC (L)2/3层的PV bc，表征了它们的内在生理、形态和突触连通性。我们发现，虽然背腹轴上的内在生理和形态大致相似，但PV bc与背侧mEC中的局部prc形成更多的连接，与靶细胞类型无关。反过来，主要的PrC亚型，锥体细胞（PC）和星状细胞（SC），以较低但相同的概率与PV bc形成连接。因此，这些数据确定抑制连通性是抑制梯度的来源，合理地解释了沿mEC背腹侧轴形成的发散网格场。
The medial entorhinal cortex (mEC) shows a high degree of spatial tuning, predominantly grid cell activity, which is reliant on robust, dynamic inhibition provided by local interneurons (INs). In fact, feedback inhibitory microcircuits involving fast-spiking parvalbumin (PV) basket cells (BCs) are believed to contribute dominantly to the emergence of grid cell firing in principal cells (PrCs). However, the strength of PV BC-mediated inhibition onto PrCs is not uniform in this region, but high in the dorsal and weak in the ventral mEC. This is in good correlation with divergent grid field sizes, but the underlying morphologic and physiological mechanisms remain unknown. In this study, we examined PV BCs in layer (L)2/3 of the mEC characterizing their intrinsic physiology, morphology and synaptic connectivity in the juvenile rat. We show that while intrinsic physiology and morphology are broadly similar over the dorsoventral axis, PV BCs form more connections onto local PrCs in the dorsal mEC, independent of target cell type. In turn, the major PrC subtypes, pyramidal cell (PC) and stellate cell (SC), form connections onto PV BCs with lower, but equal probability. These data thus identify inhibitory connectivity as source of the gradient of inhibition, plausibly explaining divergent grid field formation along this dorsoventral axis of the mEC.