Lübke J, Frotscher M, Spruston N
Anatomisches Institut, Albert-Ludwigs-Universität Freiburg, D-79104 Freiburg, Germany.
J Neurophysiol. 1998 Mar;79(3):1518-34. doi: 10.1152/jn.1998.79.3.1518.
Because of their strategic position between the granule cell and pyramidal cell layers, neurons of the hilar region of the hippocampal formation are likely to play an important role in the information processing between the entorhinal cortex and the hippocampus proper. Here we present an electrophysiological characterization of anatomically identified neurons in the fascia dentata as studied using patch-pipette recordings and subsequent biocytin-staining of neurons in slices. The resting potential, input resistance (RN), membrane time constant (taum), "sag" in hyperpolarizing responses, maximum firing rate during a 1-s current pulse, spike width, and fast and slow afterhyperpolarizations (AHPs) were determined for several different types of hilar neurons. Basket cells had a dense axonal plexus almost exclusively within the granule cell layer and were distinguishable by their low RN, short taum, lack of sag, and rapid firing rates. Dentate granule cells also lacked sag and were identifiable by their higher RN, longer taum, and lower firing rates than basket cells. Mossy cells had extensive axon collaterals within the hilus and a few long-range collaterals to the inner molecular layer and CA3c and were characterized physiologically by small fast and slow AHPs. Spiny and aspiny hilar interneurons projected primarily either to the inner or outer segment of the molecular layer and had a dense intrahilar axonal plexus, terminating onto somata within the hilus and CA3c. Physiologically, spiny hilar interneurons generally had higher RN values than mossy cells and a smaller slow AHP than aspiny interneurons. The specialized physiological properties of different classes of hilar neurons are likely to be important determinants of their functional operation within the hippocampal circuitry.
由于海马结构门区的神经元处于颗粒细胞层和锥体细胞层之间的战略位置，它们可能在内嗅皮质和海马本身之间的信息处理中发挥重要作用。在此，我们展示了对齿状回中解剖学上已确定的神经元的电生理特性研究，该研究使用膜片钳记录以及随后对切片中的神经元进行生物胞素染色。我们测定了几种不同类型的门区神经元的静息电位、输入电阻（RN）、膜时间常数（taum）、超极化反应中的“下垂”、1秒电流脉冲期间的最大放电率、动作电位宽度以及快速和慢速超极化后电位（AHPs）。篮状细胞几乎仅在颗粒细胞层内有密集的轴突丛，其特征为低RN、短taum、无下垂以及快速放电率。齿状颗粒细胞也无下垂，且与篮状细胞相比，其具有更高的RN、更长的taum以及更低的放电率，以此可识别。苔藓细胞在门区内有广泛的轴突侧支，并向分子层内侧和CA3c有一些长距离侧支，其生理特征为小的快速和慢速AHPs。有棘和无棘的门区中间神经元主要投射到分子层的内侧或外侧段，且在门区内有密集的轴突丛，终止于门区和CA3c内的胞体上。在生理上，有棘门区中间神经元的RN值通常比苔藓细胞高，且慢速AHP比无棘中间神经元小。不同类别的门区神经元的特殊生理特性可能是它们在海马回路中功能运作的重要决定因素。
