Department of Neurosciences, Case Western Reserve University, Cleveland, Ohio, USA.
Nat Neurosci. 2010 Feb;13(2):213-22. doi: 10.1038/nn.2458. Epub 2009 Dec 27.
Here we found that perforant path stimulation in rat hippocampal slices evoked long-lasting barrages of synaptic inputs in subpopulations of dentate gyrus mossy cells and hilar interneurons. Synaptic barrages triggered persistent firing in hilar neurons (hilar up-states). We found that synaptic barrages originate from semilunar granule cells (SGCs), glutamatergic neurons in the inner molecular layer that generate long-duration plateau potentials in response to excitatory synaptic input. MK801, nimodipine and nickel all abolished both stimulus-evoked plateau potentials in SGCs and synaptic barrages in downstream hilar neurons without blocking fast synaptic transmission. Hilar up-states triggered functional inhibition in granule cells that persisted for more than 10 s. Hilar cell assemblies, identified by simultaneous triple and paired intracellular recordings, were linked by persistent firing in SGCs. Population responses recorded in hilar neurons accurately encoded stimulus identity. Stimulus-evoked up-states in the dentate gyrus represent a potential cellular basis for hippocampal working memory.
在这里，我们发现，在大鼠海马切片中，穿通通路刺激可引发齿状回颗粒细胞和门区中间神经元亚群中的长时突触传入爆发。突触爆发触发门区神经元的持续放电（门区兴奋状态）。我们发现，突触爆发源自半月形颗粒细胞（SGC），即内分子层中的谷氨酸能神经元，它们对兴奋性突触输入产生长时程平台电位。MK801、尼莫地平、镍离子均能消除 SGC 中刺激诱发的平台电位和下游门区神经元中的突触爆发，而不阻断快速突触传递。门区兴奋状态触发颗粒细胞的功能抑制，持续时间超过 10 秒。通过同时进行的三重和成对细胞内记录鉴定的门区细胞集合，通过 SGC 的持续放电而相互连接。在门区神经元中记录的群体反应准确地编码了刺激的特征。齿状回中的刺激诱发兴奋状态代表了海马工作记忆的潜在细胞基础。
