Department of Neurophysiology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.
Eur J Neurosci. 2014 Jun;39(11):1720-8. doi: 10.1111/ejn.12476. Epub 2014 Jan 9.
Calcium imaging of individual neurons is widely used for monitoring their activity in vitro and in vivo. Synthetic fluorescent calcium indicator dyes are commonly used, but the resulting calcium signals sometimes suffer from a low signal-to-noise ratio (SNR). Therefore, it is difficult to detect signals caused by single action potentials (APs) particularly from neurons in vivo. Here we showed that a recently developed calcium indicator dye, Cal-520, is sufficiently sensitive to reliably detect single APs both in vitro and in vivo. In neocortical neurons, calcium signals were linearly correlated with the number of APs, and the SNR was > 6 for in vitro slice preparations and > 1.6 for in vivo anesthetised mice. In cerebellar Purkinje cells, dendritic calcium transients evoked by climbing fiber inputs were clearly observed in anesthetised mice with a high SNR and fast decay time. These characteristics of Cal-520 are a great advantage over those of Oregon Green BAPTA-1, the most commonly used calcium indicator dye, for monitoring the activity of individual neurons both in vitro and in vivo.
钙成像技术广泛应用于体外和体内单个神经元活性的监测。常用的合成荧光钙指示剂染料，但得到的钙信号有时信噪比（SNR）较低。因此，很难检测到单个动作电位（APs）引起的信号，特别是来自体内神经元的信号。本文作者表示，最近开发的钙指示剂染料 Cal-520 足够灵敏，可在体外和体内可靠地检测到单个 APs。在新皮层神经元中，钙信号与 APs 的数量呈线性相关，体外切片制备的 SNR ＞6，麻醉小鼠的 SNR ＞1.6。在麻醉小鼠的小脑浦肯野细胞中，通过 climbing fiber 输入诱发的树突钙瞬变具有高 SNR 和快速衰减时间，可清晰观察到。与最常用的钙指示剂 Oregon Green BAPTA-1 相比，Cal-520 的这些特性对于体外和体内单个神经元活性的监测具有很大优势。
