Functional properties of electrical synapses between inhibitory interneurons of neocortical layer 4
Functional properties of electrical synapses between inhibitory interneurons of neocortical layer 4
复制标题
DOI：
10.1152/jn.00520.2004
复制
发表时间：
2005-01-01
影响因子：
2.5
通讯作者：
Connors, BW
中科院分区：
文献类型：
--
作者：
Gibson, JR;Beierlein, M;Connors, BW
大脑皮层内GABA能抑制性中间神经元之间存在电突触已被证实，但其功能特性尚未详细描述。我们从成对的电耦合快速放电(FS)或低阈值放电(LTS)神经元中进行了全细胞记录，并在一些细胞中填充了生物细胞素以进行形态重建。数据被用来建立隔室电缆模型并指导数学分析。我们分析了FS和LTS神经元突触后电位(EPSPS)的时程和幅度，EPSPS是由突触前动作电位产生的阈值下事件。这些结果表明，EPSP的产生在两种类型的细胞中都是一个主要的线性过程，突触前放电既有单个的，也有重复的。非线性使EPSP接近尖峰阈值，但我们的数据表明，潜在的突触电流仍然是一个线性过程。在更长的时间尺度上，细胞间的电信号也似乎是线性的。电耦合的FS和LTS神经元的电缆模型表明，所分析的电突触平均在距离胞体50微米以内。最后，我们证明了两个抑制细胞之间的电耦合促进了所有尖峰频率的同步性。这与由相同细胞诱发的相互抑制突触后电位(IPSP)的效果形成对比，IPSP促进频率低于约100赫兹的反同步放电。电耦合抵消了IPSP诱导的反同步行为，促进了峰同步。我们的结果表明，抑制性中间神经元之间的电突触最容易被描述为促进放电同步性的低通线性滤波器。
The existence of electrical synapses between GABAergic inhibitory interneurons in neocortex is well established, but their functional properties have not been described in detail. We made whole cell recordings from pairs of electrically coupled fast-spiking (FS) or low threshold spiking (LTS) neurons, and filled some cells with biocytin for morphological reconstruction. Data were used to create compartmental cable models and to guide mathematical analysis. We analyzed the time course and amplitude of electrical postsynaptic potentials (ePSPs), the subthreshold events generated by presynaptic action potentials, in both FS and LTS neurons. The results imply that the generation of ePSPs is predominantly a linear process in both cell types for presynaptic firing of both single and repetitive spikes. Nonlinearities shape ePSPs near spike threshold, but our data suggest that the underlying synaptic current is still a linear process. Cell-to-cell electrical signaling on longer timescales also appears to be linear. Cable models of electrically coupled FS and LTS neurons imply that the analyzed electrical synapses are, on average, within 50 mum of the soma. Finally, we show that electrical coupling between 2 inhibitory cells promotes synchrony at all spiking frequencies. This contrasts with the effect of reciprocal inhibitory postsynaptic potentials (IPSPs) evoked by the same cells, which promote antisynchronous firing at frequencies less than about 100 Hz. Electrical coupling counteracts the antisynchronous behavior induced by IPSPs and facilitates spiking synchrony. Our results suggest that electrical synapses among inhibitory interneurons are most readily described as low-pass linear filters that promote firing synchrony.