Laboratory of Systems Neuroscience, Tohoku University Graduate School of Life Sciences, Sendai, Japan; Kavli Institute for Systems Neuroscience, Center for Computational Neuroscience, Egil and Pauline Braathen and Fred Kavli Center for Cortical Microcircuits, NTNU Norwegian University of Science and Technology, Trondheim, Norway; PRESTO, Japan Science and Technology Agency (JST), Tokyo, Japan.
Institute of Physiology and Pathophysiology, Medical Faculty, Heidelberg University, Heidelberg, Germany.
Cell Rep. 2023 Jan 31;42(1):112001. doi: 10.1016/j.celrep.2023.112001. Epub 2023 Jan 20.
The general understanding of hippocampal circuits is that the hippocampus and the entorhinal cortex (EC) are topographically connected through parallel identical circuits along the dorsoventral axis. Our anterograde tracing and in vitro electrophysiology data, however, show a markedly different dorsoventral organization of the hippocampal projection to the medial EC (MEC). While dorsal hippocampal projections are confined to the dorsal MEC, ventral hippocampal projections innervate both dorsal and ventral MEC. Further, whereas the dorsal hippocampus preferentially targets layer Vb (LVb) neurons, the ventral hippocampus mainly targets cells in layer Va (LVa). This connectivity scheme differs from hippocampal projections to the lateral EC, which are topographically organized along the dorsoventral axis. As LVa neurons project to telencephalic structures, our findings indicate that the ventral hippocampus regulates LVa-mediated entorhinal-neocortical output from both dorsal and ventral MEC. Overall, the marked dorsoventral differences in hippocampal-entorhinal connectivity impose important constraints on signal flow in hippocampal-neocortical circuits.
人们通常认为，海马体和内嗅皮层（entorhinal cortex，EC）通过沿背腹轴的平行相同回路进行拓扑连接。然而，我们的顺行示踪和体外电生理学数据显示，海马体投射到内侧 EC（medial EC，MEC）的背腹组织具有明显不同的组织。虽然背侧海马体的投射仅限于背侧 MEC，但腹侧海马体的投射支配背侧和腹侧 MEC。此外，背侧海马体优先靶向 LVb 神经元，而腹侧海马体主要靶向 LVa 细胞。这种连接模式与海马体投射到外侧 EC 不同，后者沿背腹轴进行拓扑组织。由于 LVa 神经元投射到端脑结构，我们的发现表明，腹侧海马体调节来自背侧和腹侧 MEC 的 LVa 介导的内嗅皮层-新皮层输出。总的来说，海马体-内嗅皮层连接的明显背腹差异对海马体-新皮层回路中的信号流施加了重要限制。
