Gulyás A I, Miles R, Sík A, Tóth K, Tamamaki N, Freund T F
Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest.
Nature. 1993 Dec 16;366(6456):683-7. doi: 10.1038/366683a0.
Morphologically a synapse consists of a presynaptic release site containing vesicles, a postsynaptic element with membrane specialization, and a synaptic cleft between them. The number of release sites shapes the properties of synaptic transmission between neurons. Although excitatory interactions between cortical neurons have been examined, the number of release sites remains unknown. We have now recorded excitatory postsynaptic potentials evoked by single pyramidal cells in hippocampal interneurons and visualized both cells using biocytin injections. Light and electron microscopy showed that excitatory postsynaptic potentials were mediated by a single synapse. We also reconstructed the entire axon arborization of single pyramidal cells, filled in vivo, in sections counterstained for parvalbumin, which selectively marks basket and axo-axonic cells. Single synaptic contacts between pyramidal cells and parvalbumin-containing neurons were dominant (> 80%), providing evidence for high convergence and divergence in hippocampal networks.
从形态学上讲，一个突触由一个含有囊泡的突触前释放位点、一个具有膜特化的突触后元件以及它们之间的突触间隙组成。释放位点的数量决定了神经元之间突触传递的特性。尽管已经对皮质神经元之间的兴奋性相互作用进行了研究，但释放位点的数量仍然未知。我们现在记录了海马中间神经元中单个锥体细胞诱发的兴奋性突触后电位，并通过生物素注射对这两个细胞进行了可视化。光学显微镜和电子显微镜显示，兴奋性突触后电位由单个突触介导。我们还重建了在体内填充的单个锥体细胞的整个轴突分支，在对小白蛋白进行复染的切片中，小白蛋白选择性地标记篮状细胞和轴-轴突细胞。锥体细胞与含小白蛋白的神经元之间的单个突触接触占主导地位（>80%），这为海马网络中的高度汇聚和发散提供了证据。
