Cover legend: The axonal arbors of single nigrostriatal dopaminergic neurons in rat brain visualized with a Sindbis viral vector expressing membrane-targeted green fluorescent protein. The image shows axon fibers in the neostriatum projected onto a parasagittal plane. Red and blue lines indicate the axon fibers located in the striosome and matrix compartments of the neostriatum. The dopaminergic neurons formed wide and dense axonal arborizations, spanning up to 5.7% of the total volume of the neostriatum on one side. All reconstructed dopaminergic neurons innervated both striosome and matrix compartments of the neostriatum. For more information, see the article by Matsuda et al. in this issue (pages 444–453).