title: A highly sensitive fluorescent indicator dye for calcium imaging of neural activity in vitro and in vivo.
abstract: 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.
authors.affiliation: Department of Neurophysiology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.
authors.forename: Mayumi
authors.initials: M
authors.lastname: Tada
authors.forename: Atsuya
authors.initials: A
authors.lastname: Takeuchi
authors.forename: Miki
authors.initials: M
authors.lastname: Hashizume
authors.forename: Kazuo
authors.initials: K
authors.lastname: Kitamura
authors.forename: Masanobu
authors.initials: M
authors.lastname: Kano
mesh_terms: D000200:Action Potentials; D000814:Aniline Compounds / Q000494:pharmacology / Q000592:standards; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling; D002478:Cells, Cultured; D005452:Fluoresceins / Q000494:pharmacology / Q000592:standards; D005456:Fluorescent Dyes / Q000494:pharmacology / Q000592:standards*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008856:Microscopy, Fluorescence / Q000379:methods*; D019579:Neocortex / Q000166:cytology / Q000378:metabolism; D011689:Purkinje Cells / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D017966:Pyramidal Cells / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D059629:Signal-To-Noise Ratio
chemical_list: D000814:Aniline Compounds; D005452:Fluoresceins; D005456:Fluorescent Dyes; C503942:Oregon green 488 BAPTA-1; D002118:Calcium
keywords: cerebellum; mouse; neocortex; population activity; two-photon imaging