Calcium indicator GCaMP6m lentivirus is a preparation of highly purified lentiviral particles, ready-to-use for monitoring calcium signal in virtually any type of mammalian cells. GCaMP is one of the most widely used calcium indicators in neuronal imaging and calcium cell biology. When calcium is present, fusion calcium indicator undergoes a conformational change and GFP fluorescence is activated from quenched status. The newly developed GCaMP6 shows superior brightness and ultrasensitivity to calcium concentration change. This lentivirus expresses the medium version of GCaMP6 (GCaMP6m) under the control of the human neuron-specific synapsin 1 promoter with puromycin as a selection marker.