BACKGROUND:Epigenetic regulation is a level of transcriptional regulation that occurs in addition to the genetic programming found in biological systems.In the brain,the epigenetic machinery gives the system an opportunity to adapt to a given environment to help not only the individual but also the species survive and expand.However,such a regulatory system has risks,as mutations resulting from epigenetic regulation can cause severe neurological or psychiatric disorders.OBJECTIVE:Here,we review the most recent findings regarding the epigenetic mechanisms that control the activitydependent gene transcription leading to synaptic plasticity and brain fimction and the defects in these mechanisms that lead to neurological disorders.METHODS:A search was carried out systematically,searching all relevant publications up to June 2017,using the PubMed search engine.The following keywords were used:"activity induced epigenetic," "gene transcription," and "neurological disorders."RESULTS:A wide range of studies focused on the roles of epigenetics in transgenerational inheritance,neural differentiation,neural circuit assembly and brain diseases.Thirty-one articles focused specifically on activity-induced epigenetic modifications that regulated gene transcription and memory formation and consolidation.CONCLUSION:Activity-dependent epigenetic mechanisms of gene expression regulation contribute to basic neuronal physiology,and defects were associated with an elevated risk for brain disorders.