The contribution of Shaker K+ channels to the information capacity of Drosophila photoreceptors
The contribution of Shaker K+ channels to the information capacity of Drosophila photoreceptors
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DOI：
10.1038/nature01384
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发表时间：
2003-02-06
期刊：
影响因子：
64.8
通讯作者：
Weckström, M
中科院分区：
文献类型：
--
作者：
Niven, JE;Vähäsöyrinki, M;Weckström, M
一系列快速失活的电压门控K+通道分布在脊椎动物和无脊椎动物的神经系统中（1-5）。虽然这些通道被认为是通过衰减电压信号来调节神经元的兴奋性，但它们的具体功能往往知之甚少。我们通过记录野生型和Shaker突变型光感受器的细胞内记录，研究了果蝇光感受器中典型的失活K+电导Shaker（6，7）的作用（8，9）。在这里，我们表明，Shaker K+电导的损失会导致光感受器的信噪比显著降低，在完全光适应的条件下，这些细胞的信息容量会降低50%。通过将实验与建模相结合，我们表明Shaker K+通道的失活放大了电压信号，使感光细胞能够更有效地利用其电压范围。振荡器电导的损失衰减了电压信号，并引起阻抗的补偿性降低。我们的结果证明了Shaker K+电导对于神经编码精确性的重要性，以及作为选择性放大神经元中分级信号的机制，并强调了补偿机制对神经元信息处理的影响。
An array of rapidly inactivating voltage-gated K+ channels is distributed throughout the nervous systems of vertebrates and invertebrates(1-5). Although these channels are thought to regulate the excitability of neurons by attenuating voltage signals, their specific functions are often poorly understood. We studied the role of the prototypical inactivating K+ conductance, Shaker(6,7), in Drosophila photoreceptors(8,9) by recording intracellularly from wild-type and Shaker mutant photoreceptors. Here we show that loss of the Shaker K+ conductance produces a marked reductionin the signal-to-noise ratio of photoreceptors, generating a 50% decrease in the information capacity of these cells in fully light-adapted conditions. By combining experiments with modelling, we show that the inactivation of Shaker K+ channels amplifies voltage signals and enables photoreceptors to use their voltage range more effectively. Loss of the Shaker conductance attenuated the voltage signal and induced a compensatory decrease in impedance. Our results demonstrate the importance of the Shaker K+ conductance for neural coding precision and as a mechanism for selectively amplifying graded signals in neurons, and highlight the effect of compensatory mechanisms on neuronal information processing.