Mora, F., Segovia, G.&del Arco, A. 'Aging, plasticity and environmental enrichment: structural changes and neurotransmitter dynamics in several areas of the brain'. Brain Research Review, 55, 78–88 (2007). Kozorovitskiy, Y. et al. 'Experience induces structural and biochemical changes in the adult primate brain'. Proceedings of the National Academy of Sciences of the United States of America, 102, 17478–82 (2005).