Fiber Photometry System

How the Fiber Photometry System Works

To understand how the fiber photometry system works, the calcium indicators are a good place to start. From a microscopic perspective, several important processes,including neurotransmitter release and membrane excitability, are regulated by calcium ions in neurons. GECIs change their ability to fluoresce based on whether or not they are bound to calcium. Since the internal concentration of calcium in neurons is very tightly regulated and voltage-gated calcium channels open when a neuron fires an action potential,transient increases in internal calcium concentration, which result in a transient rise in the ability of a GECI to fluorescence, can be a good proxy for neuronal firing. A two-wavelength GCaMP fiber photometry system ( 405nm + 470nm ) is utilized for GCaMP recording. Given that GCaMP fluoresces only when bound to calcium ions, 405 nm LED source is used to photoexcite isosbestic points of the fluorophore. The GCaMP fiber photometry system can provide critical insight into calcium dynamics by recording the calcium-independent GCaMP fluorescence .