Fast calcium sensor proteins for monitoring neural activity

Aleksandra Badura; Xiaonan R. Sun; Andrea Giovannucci; Laura A. Lynch; Samuel S.. H. Wang

doi:10.1117/1.NPh.1.2.025008

17 October 2014 Fast calcium sensor proteins for monitoring neural activity

Aleksandra Badura, Xiaonan R. Sun, Andrea Giovannucci, Laura A. Lynch, Samuel S.. H. Wang

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Neurophotonics, Vol. 1, Issue 2, 025008 (October 2014). https://doi.org/10.1117/1.NPh.1.2.025008

Abstract

A major goal of the BRAIN Initiative is the development of technologies to monitor neuronal network activity during active information processing. Toward this goal, genetically encoded calcium indicator proteins have become widely used for reporting activity in preparations ranging from invertebrates to awake mammals. However, slow response times, the narrow sensitivity range of Ca²+ and in some cases, poor signal-to-noise ratio still limit their usefulness. Here, we review recent improvements in the field of neural activity-sensitive probe design with a focus on the GCaMP family of calcium indicator proteins. In this context, we present our newly developed Fast-GCaMPs, which have up to 4-fold accelerated off-responses compared with the next-fastest GCaMP, GCaMP6f. Fast-GCaMPs were designed by destabilizing the association of the hydrophobic pocket of calcium-bound calmodulin with the RS20 binding domain, an intramolecular interaction that protects the green fluorescent protein chromophore. Fast-GCaMP6f-RS06 and Fast-GCaMP6f-RS09 have rapid off-responses in stopped-flow fluorimetry, in neocortical brain slices, and in the intact cerebellum in vivo. Fast-GCaMP6f variants should be useful for tracking action potentials closely spaced in time, and for following neural activity in fast-changing compartments, such as axons and dendrites. Finally, we discuss strategies that may allow tracking of a wider range of neuronal firing rates and improve spike detection.

CC BY: © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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Aleksandra Badura, Xiaonan R. Sun, Andrea Giovannucci, Laura A. Lynch, and Samuel S.. H. Wang "Fast calcium sensor proteins for monitoring neural activity," Neurophotonics 1(2), 025008 (17 October 2014). https://doi.org/10.1117/1.NPh.1.2.025008

Published: 17 October 2014

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