Cover legend: High-magnification confocal image showing the fine structure of a perineuronal net (green) surrounding a neuron. Perineuronal nets are a special type of extracellular matrix with high content in hyaluronan and associated primarily with interneurons. Anti-vesicular glutamate transporter-1 (red) and anti-vesicular inhibitory amino acid transporter (blue) antibodies were used to detect excitatory and inhibitory synapses, respectively. For related information, see the article by Arranz et al. (pages 6164–6176).