Amplification of high-frequency synaptic inputs by active dendritic membrane processes
Amplification of high-frequency synaptic inputs by active dendritic membrane processes
复制标题
DOI：
10.1038/379639a0
复制
发表时间：
1996-02-15
期刊：
影响因子：
64.8
通讯作者：
Borst, A
中科院分区：
文献类型：
--
作者：
Haag, J;Borst, A
在许多神经细胞的树突中发现了活跃的膜机制(1-7)。然而，它们对树突信号处理的贡献仍不清楚(8)，因为很少有实验制剂能够详细表征正常条件下的树突生理学。为了研究体内制剂中活性树突过程的功能含义，我们比较了果蝇视觉系统的不同类型的非尖峰、运动敏感中间神经元的响应特性，其中只有一个在其轴突和树突中配备了快速钠内向电流。我们在此报告，具有快速激活钠电流的细胞可以对其突触输入信号的时间变化做出反应，其频率比缺乏此类电流的细胞高得多。因此，快速的钠电流会导致突触信号的频率依赖性放大，从而增强细胞对瞬态输入的响应，否则这些响应会因树突树的被动特性而减弱。
ACTIVE membrane mechanisms have been found in the dendrites of many nerve cells(1-7). Their contribution to dendritic signal processing, however, remains unclear(8) because few experimental preparations allow for detailed characterization of dendritic physiology under normal conditions, To investigate the functional implications of active dendritic processes in an in vivo preparation, we compared the response properties of different types of non-spiking, motion-sensitive interneurons of the fly visual system, only one of which is equipped with a fast sodium inward current in its axon as well as in its dendrite. We report here that cells with fast activating sodium currents can respond to temporal changes in their synaptic input signals up to much higher frequencies than can those which lack such currents. Thus fast sodium currents lead to a frequency-dependent amplification of synaptic signals, enhancing cellular responses specifically to transient inputs which otherwise would be attenuated because of the passive properties of the dendritic tree.