Table 1.

Advantages and disadvantages of in vivo GCaMP imaging.

Advantages	Disadvantages
Simultaneous visualization of Ca2+ transients in large populations of cells	Can be difficult to observe targets in highly scattering tissue
Excellent spatial resolution	Limited temporal resolution
Improved preservation of physiological condition	Not a direct measurement of action potential firing
Does not require application or injection of Ca2+-sensitive dyes	Can be susceptible to effects of Ca2+-buffering
Uses minimally-invasive properties of light	Cannot measure neurophysiological characteristics such as action potential number, frequency, duration
Maintenance of somatotopic organization	Level of fluorescence can be affected by variable GCaMP expression levels
Can be inserted into mouse genome, allowing for easy and repeatable expression between generations	Susceptible to effects of phototoxicity
Can be combined with other fluorophores for multichannel imaging