To trace the longer pathways that interconnect different brain regions, CBS labs developed a genetic method to label each individual nerve cell a different color to identify and track axons and dendrites over long distances. With light microscopy, scientists image the branching patterns and connections of all the axons within a region of the nervous system in transgenic mice that express a number of different fluorescent proteins in individual neurons. The idea here is to color-code the individual “wires” and “nodes.” The images below (all courtesy of J. Lichtman) give an indication of the power of this approach.


Livet et al., Nature 2007

Lichtman et al., Nature Reviews Neuroscience 2008