Banks Paul J, Warburton E Clea, Bashir Zafar I
School of Physiology, Pharmacology & Neuroscience, University of Bristol, Biomedical Sciences Building, University Walk, Bristol BS8 1TD, UK.
Cereb Cortex Commun. 2021 Apr 14;2(2):tgab029. doi: 10.1093/texcom/tgab029. eCollection 2021.
The nucleus reuniens and rhomboid nuclei of the thalamus (ReRh) are reciprocally connected to a range of higher order cortices including hippocampus (HPC) and medial prefrontal cortex (mPFC). The physiological function of ReRh is well predicted by requirement for interactions between mPFC and HPC, including associative recognition memory, spatial navigation, and working memory. Although anatomical and electrophysiological evidence suggests ReRh makes excitatory synapses in mPFC there is little data on the physiological properties of these projections, or whether ReRh and HPC target overlapping cell populations and, if so, how they interact. We demonstrate in ex vivo mPFC slices that ReRh and HPC afferent inputs converge onto more than two-thirds of layer 5 pyramidal neurons, show that ReRh, but not HPC, undergoes marked short-term plasticity during theta frequency transmission, and that HPC, but not ReRh, afferents are subject to neuromodulation by acetylcholine acting via muscarinic receptor M2. Finally, we demonstrate that pairing HPC followed by ReRh (but not pairing ReRh followed by HPC) at theta frequency induces associative, NMDA receptor dependent synaptic plasticity in both inputs to mPFC. These data provide vital physiological phenotypes of the synapses of this circuit and provide a novel mechanism for HPC-ReRh-mPFC encoding.
丘脑的 reunien 核和菱形核（ReRh）与包括海马体（HPC）和内侧前额叶皮质（mPFC）在内的一系列高级皮质相互连接。mPFC 和 HPC 之间相互作用的需求，包括联想识别记忆、空间导航和工作记忆，很好地预测了 ReRh 的生理功能。尽管解剖学和电生理学证据表明 ReRh 在 mPFC 中形成兴奋性突触，但关于这些投射的生理特性的数据很少，也不清楚 ReRh 和 HPC 是否靶向重叠的细胞群体，如果是，它们如何相互作用。我们在离体的 mPFC 切片中证明，ReRh 和 HPC 的传入输入汇聚到超过三分之二的 5 层锥体神经元上，表明 ReRh 在 θ 频率传递过程中经历显著的短期可塑性，而 HPC 则没有，并且 HPC 的传入纤维受到通过毒蕈碱受体 M2 起作用的乙酰胆碱的神经调节，而 ReRh 的传入纤维则不受影响。最后，我们证明在 θ 频率下先给予 HPC 再给予 ReRh（而不是先给予 ReRh 再给予 HPC）的配对会在 mPFC 的两个输入中诱导出联想性的、NMDA 受体依赖性的突触可塑性。这些数据提供了该回路突触的重要生理表型，并为 HPC - ReRh - mPFC 编码提供了一种新机制。
