Cover legend: A hippocampal pyramidal neuron (red) innervated by GABAergic axons (black) depicted in traditional Chinese watercolor. Elevation of neuronal activity rapidly increases the strength of these synapses, as well as the number of active contacts, through BDNF-dependent signaling. Artwork by Jiafeng Zhao of the Oriental Morning Post, Shanghai, China. For more information, see the article by Peng et al. in this issue (pages 16220–16231).