This image shows a perineuronal net surrounding a projection neuron in the deep medial nucleus of mouse cerebellum. The tissue is stained with Wisteria floribunda agglutinin to label the perineuronal net (pink) and SMI32 (blue) to label neurons. Perineuronal nets are extracellular matrix structures that help stabilize synaptic changes. They may play roles in synaptic plasticity, learning and memory, schizophrenia, Alzheimer's disease, and addiction. For more information, see the symposium review article by Sorg et al. (pages 11459–11468).