Cover picture: Pseudocolor image of the mushroom bodies in the Drosophila brain expressing camgaroo-2, a calcium indicator derived from yellow fluorescent protein. This image highlights the neuropil areas that contain the axonal projections from mushroom body neurons. The neuropil areas include the  lobe (the ankle portion of the image), the heel, and the , ', and  lobes (the three toes in the image from bottom to top, respectively). Camgaroo indicators supplied as transgenes were used to monitor calcium concentrations in the mushroom body axons as the neurons depolarize. Warmer colors indicate higher concentrations of calcium as reported by the indicator. For details, see the article by Yu et al. in this issue (pages 64–72).