A confocal image, rendered as an oil painting, shows the hippocampal dentate gyrus, with the primary excitatory cell type, the dentate granule cells, in blue. Hilar mossy cells and their axons were labelled using a viral method shown in red. New work shows that activating versus inhibiting mossy cells often produces opposing effects on cognitive and anxiety-like behaviors. See Botterill et al. for details. (pages 2475–2495). Cover image: Justin Botterill