This confocal image shows a topdown view of two serotonergic modulatory neurons, the CSD neurons, in the Drosophila brain. The CSD neurons are visualized with GFP (green) and serotonin antibody labeling is shown in magenta. The CSD neurons interconnect multiple neural networks that support olfactory processing. For more information, see the article by Coates et al. (pages 7318–7331).