Fast calcium sensor proteins for monitoring neural activity

• DOI: 10.1117/1.nph.1.2.025008
• Publication Date: 2014-10-17T15:31:05Z
• Authors: Aleksandra Badura; Xiaonan Richard Sun; Andrea Giovannucci; Laura A. Lynch; Samuel S.-H. Wang
• Keywords: Calcium imaging; Biological neural network; Calcium Signaling

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