GCaMP is a genetically encoded calcium indicator (GECI) which was created from a fusion of green fluorescent protein (GFP), calmodulin, and M13, a peptide sequence from myosin light chain kinase. GECI binds Ca2+ and induce a change in fluorescence signal, which allows measuring action potentials and other receptor activation events that trigger Ca2+ fluxes. The advantage of GECI's are that they can be genetically specified for studies in living organisms.The new novel GCaMP6 have increased ΔF/F0 and faster kinetics compared to previous GCaMP3 and GCaMP5G.This adenovirus expresses GCaMP6s.