Table 2. Characteristics of FGCaMP and GCaMP6s calcium indicators responses to electrical intracellular stimulation of neurons expressing these indicators.

Protein	Number of cells	Number of APs	Rise half-time, s a	Decay half-time, s b	ΔF/ F c	SNR d
FGCaMP (493-form)	7	10	0.28±0.01	2.1±0.4	0.029±0.006	17±5
FGCaMP (402-form)	7	10	0.29±0.02	2.0±0.2	0.030±0.007	12±3
GCaMP6s	6	10	0.45±0.07	3.4±0.4	0.5±0.2	190±50

^a Rise half-time was measured as the time between the stimulus onset and the half-peak of response.

^b Decay half-time was calculated as the time from the peak to the half-peak at the end of the response.

^c ΔF/F₀ was calculated as (F − F₀)/F₀, where F₀ is the baseline fluorescence signal averaged over a 1-s period immediately after the start of imaging. 400 and 470 nm excitation light were used for imaging of 402- and 493-form, respectively.

^d Signal-to-noise ratio (SNR) was quantified as the peak ΔF/F₀ response over the standard deviation of the signal during a one-second period before stimulation. Values are shown as the means  ±  standard errors of the mean.