Inserm U1127, CNRS UMR7225, UPMC Université Paris 6 UMR S1127, Institut du Cerveau et de la Moelle Epinière, Sorbonne Universités, Paris 75013, France.
CNRS UMR 8119, Université Paris Descartes, France.
eNeuro. 2017 May 15;4(2). doi: 10.1523/ENEURO.0370-16.2017. eCollection 2017 Mar-Apr.
The presubiculum (PrS) is part of an interconnected network of distributed brain regions where individual neurons signal the animals heading direction. PrS sends axons to medial entorhinal cortex (MEC), it is reciprocally connected with anterior thalamic nuclei (ATNs), and it sends feedback projections to the lateral mammillary nucleus (LMN), involved in generating the head direction signal. The intrinsic properties of projecting neurons will influence the pathway-specific transmission of activity. Here, we used projection-specific labeling of presubicular neurons to identify MEC-, LMN-, and ATN-projecting neurons in mice. MEC-projecting neurons located in superficial layers II/III were mostly regular spiking pyramidal neurons, and we also identified a Martinotti-type GABAergic neuron. The cell bodies of LMN-projecting neurons were located in a well-delimited area in the middle portion of the PrS, which corresponds to layer IV. The physiology of LMN projecting, pyramidal neurons stood out with a tendency to fire in bursts of action potentials (APs) with rapid onset. These properties may be uniquely adapted to reliably transmit visual landmark information with short latency to upstream LMN. Neurons projecting to ATN were located in layers V/VI, and they were mostly regular spiking pyramidal neurons. Unsupervised cluster analysis of intrinsic properties suggested distinct physiological features for the different categories of projection neurons, with some similarities between MEC- and ATN-projecting neurons. Projection-specific subpopulations may serve separate functions in the PrS and may be engaged differently in transmitting head direction related information.
前下托（PrS）是分布于大脑区域的互联网络的一部分，其中个体神经元信号动物的行进方向。PrS 将轴突发送到内侧内嗅皮层（MEC），它与前丘脑核（ATN）呈双向连接，并将反馈投射发送到外侧乳状核（LMN），参与产生头方向信号。投射神经元的内在特性将影响活动的特定路径传递。在这里，我们使用前下托神经元的投射特异性标记来鉴定小鼠中的 MEC、LMN 和 ATN 投射神经元。位于浅层 II/III 的 MEC 投射神经元大多是规则放电的锥体神经元，我们还鉴定出一种 Martinotti 型 GABA 能神经元。LMN 投射神经元的胞体位于 PrS 的中部，有一个明确限定的区域，相当于第四层。LMN 投射的锥体神经元的生理学特征突出表现在具有快速起始的动作电位（AP）爆发性放电的趋势。这些特性可能特别适应于可靠地传递具有短潜伏期的视觉地标信息到上游的 LMN。投射到 ATN 的神经元位于 V/VI 层，它们大多是规则放电的锥体神经元。对内在特性的无监督聚类分析表明，不同投射神经元类别具有不同的生理特征，MEC 和 ATN 投射神经元之间存在一些相似之处。投射特异性亚群可能在前下托中具有不同的功能，并且可能以不同的方式参与传递与头方向相关的信息。
