What you’re seeing is the brain of an axolotl, an organism known for its ability to regenerate many organs including the limb, heart, and spinal cord. The different colors (blue, green, red) represent some of the neuronal cell types present within the brain. Incredibly, when this region of the brain is injured, the brain regenerates with fidelity, and all of these cell types are remade. This means that, somehow, the brain knows exactly which neurons were injured and will replace those, and only those, neurons.
Contributed by Ryoji Amamoto, a sixth year graduate student in the Biological and Biomedical Sciences Program at Harvard Medical School.