Also at the Janelia Research Campus, a new fluorescent molecules known as CaMPARI (calcium-modulated photoactivatable ratiometric integrator) was developed using EosFP.  The permanent green to red conversion signal was coupled with a calcium-sensitive protein, calmodulin, so that color change in the fusion construct depended on the release of calcium accompanied by neural activity. CaMPARI is able to permanently mark neurons that are active at an any time and can also be targeted to synapses.  This visualization is possible across a wide amount of brain tissue as opposed to the limited view available with using a microscope.  It also allows for the visualization of neural activity during complicated behaviors as the organism under study is allowed to move freely, rather than under a microscope. It also allows for the observation of neurons during specific behavior periods.  CaMPARI has, thus far, been used to label active neural circuits in mice, zebrafish and fruit flies.