Synaptic transmission monitoring has been problematic due to several shortcomings from measuring instruments and the miniature nature of nerve terminals. The advent of fluorescent protein calcium sensors has improved our understanding, especially of lighting neural circuit and monitoring calcium transients. Notably among them is the GCaMP family of fluorescent sensors. Subsequent development of numerous types of GCAMP's has improved our understanding of neural circuitry and mechanism behind

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... rous neurodegenerative diseases. The attachment of a vesicular protein synaptophysin to GCaMP2 which led to SyGCaMP2 has two major advantages over existing cytoplasmic GECI in detecting electrical activities of neurones; (a) it identified the locations of synapses and (b) had a linear response over a wider range of spike frequencies [23]. Here we explored the various GCaMP fluorescent sensors, their advantages and disadvantages.