BDNF and brain disorder: For example, Pang and Hannan (2013) described enhancement of cognitive function in animal models of brain disease through combined environmental enrichment and physical activity, Novlovic et al. (2015) showed increased levels of BDNF facilitation of hippocampal synaptic plasticity with environmental enrichment, while Kuzumaki et al. (2011) noted that alterations in environmental stimulation induced epigenetic modification of the BDNF gene.