Abstract
Genetically encoded fluorescent indicators, combined with optical imaging, enable the detection of physiologically or behaviorally relevant neural activity with high spatiotemporal resolution. Recent developments in protein engineering and screening strategies have improved the dynamic range, kinetics, and spectral properties of genetically encoded fluorescence indicators of brain chemistry. Such indicators have detected neurotransmitter and calcium dynamics with high signal-to-noise ratio at multiple temporal and spatial scales in vitro and in vivo. This review summarizes the current trends in these genetically encoded fluorescent indicators of neurotransmitters and calcium, focusing on their key metrics and in vivo applications.
Highlights
The expansion of animal driver lines expressing a recombinase, including zebrafish Tol2kit [5], GAL4 fly lines [6], Cre-lox [7,8], and FLP-FRT mice systems [9], have enabled more robust and sophisticated control of gene expression [10,11]. These advancements in viral vectors and transgenic systems have tailored the expression of genetically encoded fluorescent indicators and narrowly specified the detection of neural activity
This work reviews bacterial periplasmic-binding protein (PBP)-based indicators (Figure 1a,d), Gprotein-coupled receptor (GPCR)-based indicators (Figure 1b,e), and calcium-binding protein-based indicators (Figure 1c,f). Both classes use two architectures to report the action of the sensing domain with a fluorescence change, either through a Förster resonance energy transfer (FRET) architecture or a circularly permuted fluorescent protein architecture
GECIs typically consist of a calcium-binding domain, a binding domain target peptide, and a reporter element based either on a single fluorescent proteins (FPs) or a FRET pair
Summary
The calcium ions activate various vesicle transport proteins to induce neurotransmitter exocytosis Neurotransmitters reach their postsynaptic targets by traversing the extracellular space in multiple ways. The interrogation of complex and diverse neural processes requires a detailed examination of how specific neuron types contribute to neural circuit functions Such investigations have demanded tools that allow the noninvasive detection of neural activity with genetic specificity in vivo. This challenge is partially met by recently engineered genetically encoded voltage indicators (GEVIs) and genetically encoded fluorescent indicators of brain chemistry.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
