INFLUENCE OF ELECTRIC-FIELDS ON THE EXCITABILITY OF GRANULE CELLS IN GUINEA-PIG HIPPOCAMPAL SLICES
INFLUENCE OF ELECTRIC-FIELDS ON THE EXCITABILITY OF GRANULE CELLS IN GUINEA-PIG HIPPOCAMPAL SLICES
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DOI：
10.1113/jphysiol.1981.sp013897
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发表时间：
1981-01-01
影响因子：
5.5
通讯作者：
JEFFERYS, JGR
中科院分区：
文献类型：
--
作者：
JEFFERYS, JGR
在体外保存的豚鼠海马颗粒细胞层记录单突触诱发电位。持续时间为25-250 m的电流脉冲在沐浴液中的总电极之间穿过切片。极化电流改变了颗粒细胞的兴奋性，这是通过突触后反应中颗粒细胞数量放电的变化来判断的。所有持续时间的极化至少在质量上有相似的效果。从树突到细胞体的常规电流增加了兴奋性（反之亦然）。这与在颗粒细胞体上或靠近颗粒细胞体的尖峰触发区膜电位的改变是一致的，这是由细胞内流动的极化电流的分数所施加的。在一些实验中，极化还影响突触前截击和突触电位。当这种情况发生时，解释随之而来的人口激增的变化是错误的。当电流在树突中部或外部的小电极和远处的粗电极之间穿过细胞体层时，聚焦极化改变了颗粒细胞的兴奋性。注入树突电极的常规电流增加了其兴奋性。最小的有效极化电流引起的细胞外电压梯度为5-10 mV/mm，这比神经元同步激活或癫痫发作时在该组织中发生的电压梯度要小。这种场电位可增加颗粒细胞放电的同步性。
Monosynaptic evoked potentials were recorded from the granule cell layer of slices of guinea pig hippocampus maintained in vitro. Current pulses of 25-250 m duration were passed across the slices, between gross electrodes in the bathing liquid. Polarizing current modified the excitability of the granule cells as judged by changes in their population discharge during postsynaptic responses. All durations of polarization had at least qualitatively similar effects. Conventional current from dendrites to cell bodies increased excitability (and vice versa). This is consistent with altered membrane potential of a spike trigger zone, at or close to the granule cell bodies, imposed by the fraction of polarizing current which flows intracellularly. In some experiments polarization also affected the presynaptic volley and the synaptic potential. When this occurred, it was in the wrong sense to explain the concomitant changes in population spike. Focal polarization, where currents were applied across the cell body layer between a small electrode on the mid or outer dendritic regions and a remote gross electrode, altered granule cell excitability. Conventional current injected at the dendritic electrode increased excitability. The smallest effective polarizing currents caused extracellular voltage gradients of 5-10 mV/mm, which is less than occurs in this tissue during synchronous activation of the neurons or during seizure activity. Such field potentials could increase the synchrony of discharge of the granule cells.