Cell type-specific and time-dependent light exposure contribute to silencing in neurons expressing Channelrhodopsin-2
Cell type-specific and time-dependent light exposure contribute to silencing in neurons expressing Channelrhodopsin-2
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DOI：
10.7554/elife.01481
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发表时间：
2014-01-28
期刊：
影响因子：
7.7
通讯作者：
Arenkiel, Benjamin R.
中科院分区：
文献类型：
--
作者：
Herman, Alexander M.;Huang, Longwen;Arenkiel, Benjamin R.
通道视紫红质-2(ChR2)作为一种诱导遗传靶向神经元激活的强大工具而迅速流行起来。然而，关于光遗传刺激在不同神经元亚型之间的反应动力学的报道很少。在过度刺激的情况下，神经元可以被驱使进入去极化阻滞区，在这种状态下，神经元停止释放动作电位。在这里，我们证明了表达ChR2的神经元中的光诱导去极化阻断对特定细胞类型的稳定激活构成了实验挑战，并可能混淆对实验的解释，而实际上‘激活的’神经元在功能上是沉默的。我们在体外和体内都表明，随着光脉冲持续时间的增加，某些针对ChR2表达的神经元亚型变得越来越容易受到去极化阻断。我们发现中间神经元群体比主要兴奋性神经元对这种效应更敏感，主兴奋性神经元对光诱导的去极化阻断更具抵抗力。我们的结果强调了在使用ChR2时经验上确定目标神经元的光反应特性的必要性，特别是在旨在引发体内复杂电路反应的研究中，其中神经元活动不会与光刺激同时被记录下来。
Channelrhodopsin-2 (ChR2) has quickly gained popularity as a powerful tool for eliciting genetically targeted neuronal activation. However, little has been reported on the response kinetics of optogenetic stimulation across different neuronal subtypes. With excess stimulation, neurons can be driven into depolarization block, a state where they cease to fire action potentials. Herein, we demonstrate that light-induced depolarization block in neurons expressing ChR2 poses experimental challenges for stable activation of specific cell types and may confound interpretation of experiments when 'activated' neurons are in fact being functionally silenced. We show both ex vivo and in vivo that certain neuronal subtypes targeted for ChR2 expression become increasingly susceptible to depolarization block as the duration of light pulses are increased. We find that interneuron populations have a greater susceptibility to this effect than principal excitatory neurons, which are more resistant to light-induced depolarization block. Our results highlight the need to empirically determine the photo-response properties of targeted neurons when using ChR2, particularly in studies designed to elicit complex circuit responses in vivo where neuronal activity will not be recorded simultaneous to light stimulation.