Kelsey Martin's team at the University of California focused their imaging on the synapse, the communication junction between two neuron cells. Scientists first coated certain proteins with a fluorescent dye that starts out green, but turns red when exposed to UV light. They blasted the neurons with UV light and shifted everything to red, just to prove the dye was there. Then they bathed the cells in serotonin, a chemical that can stimulate memory formation. They were then able to watch as new green fluorescent proteins were created as the memory was made.