Department of Neurophysiology, Nara Medical University, Kashihara, Nara 634-8521, Japan.
Department of Genetic and Behavioral Neuroscience, Gunma University Graduate School of Medicine, Maebashi, Gunma 371-8511, Japan.
eNeuro. 2017 Sep 13;4(5). doi: 10.1523/ENEURO.0180-17.2017. eCollection 2017 Sep-Oct.
Gaze holding is primarily controlled by neural structures including the prepositus hypoglossi nucleus (PHN) for horizontal gaze and the interstitial nucleus of Cajal (INC) for vertical and torsional gaze. In contrast to the accumulating findings of the PHN, there is no report regarding the membrane properties of INC neurons or the local networks in the INC. In this study, to verify whether the neural structure of the INC is similar to that of the PHN, we investigated the neuronal and network properties of the INC using whole-cell recordings in rat brainstem slices. Three types of afterhyperpolarization (AHP) profiles and five firing patterns observed in PHN neurons were also observed in INC neurons. However, the overall distributions based on the AHP profile and the firing patterns of INC neurons were different from those of PHN neurons. The application of burst stimulation to a nearby site of a recorded INC neuron induced an increase in the frequency of spontaneous EPSCs. The duration of the increased EPSC frequency of INC neurons was not significantly different from that of PHN neurons. The percent of duration reduction induced by a Ca-permeable AMPA (CP-AMPA) receptor antagonist was significantly smaller in the INC than in the PHN. These findings suggest that local excitatory networks that activate sustained EPSC responses also exist in the INC, but their activation mechanisms including the contribution of CP-AMPA receptors differ between the INC and the PHN.
凝视保持主要由神经结构控制，包括舌下神经前置核（PHN）控制水平凝视，以及 Cajal 间质核（INC）控制垂直和扭转凝视。与 PHN 的累积发现相反，目前尚无关于 INC 神经元的膜特性或 INC 内局部网络的报道。在这项研究中，为了验证 INC 的神经结构是否与 PHN 相似，我们使用大鼠脑干切片中的全细胞记录来研究 INC 的神经元和网络特性。在 PHN 神经元中观察到的三种后超极化（AHP）形态和五种放电模式也在 INC 神经元中观察到。然而，INC 神经元的 AHP 形态和放电模式的总体分布与 PHN 神经元的不同。在记录的 INC 神经元附近的一个部位施加爆发刺激会导致自发 EPSC 频率增加。INC 神经元中 EPSC 频率增加的持续时间与 PHN 神经元的无显著差异。钙通透性 AMPA（CP-AMPA）受体拮抗剂引起的持续时间减少百分比在 INC 中显著小于 PHN。这些发现表明，在 INC 中也存在激活持续 EPSC 反应的局部兴奋性网络，但它们的激活机制包括 CP-AMPA 受体的贡献在 INC 和 PHN 之间存在差异。
