Harvard university researchers developed a system that causes neural circuitry to glow in any of 90 different colors. The "Brainbow" process involves inserting genes borrowed from bioluminescent jellyfish, corals, or synthetic sources. Those genes produce proteins that color individual neurons. So far, neurobiologist Jeff Lichtman and his colleagues have tested the Brainbow process on mice but unfortunately the genetic modification can't be used on humans. From Chemistry World:
The researchers will next use Brainbow to compare how these changes occur in other groups of animals and plan to create transgenic fish, insects and nematode worms incorporating the genes. But the technique may also have applications in other areas such as drug development, Lichtman says. 'This may be a good tool to study certain disorders of the nervous system where the synaptic circuitry may be miswired (such as autism spectrum disorders). If there were potential therapies being developed for these conditions this tool might be used to see the effects of these therapies in animal models,' he suggests.