A highly sensitive fluorescent indicator dye for calcium imaging of neural activity in vitro and in vivo.
Bottom Line: 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.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.
Affiliation: Department of Neurophysiology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.Show MeSH
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Mentions: As both the mean amplitude and mean SNR for each calcium transient, which we quantified above (Figs2F and G, and 4C and D), included different numbers of APs/transient, further quantification was required to compare the true performance of these indicators. Therefore, we performed simultaneous loose-seal cell-attached recordings and high-speed linescan imaging to clarify the relationship between the calcium transients and APs (Fig.5A). The amplitude of the calcium transients linearly correlated with the number of APs (Fig.5B), and the amplitude of calcium transients per spike, which was calculated as the peak amplitude divided by the number of APs, was significantly larger for Cal-520 than for OGB-1 (0.188 ± 0.008 and 0.052 ± 0.009 ΔF/F, nine and four cells, respectively, P=0.0008) (Fig.5C). The SNR per spike was also superior for Cal-520 (1.69 ± 0.08 and 0.54 ± 0.04, nine and four cells, respectively, P=0.002) (Fig.5D). It is notable that Cal-520 could clearly detect calcium signals evoked by single APs, which were barely detectable using OGB-1 (Fig.5E).
Affiliation: Department of Neurophysiology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.