In this project we address by a combination of in vivo imaging and molecular techniques the question how brain plasticity is regulated at the cellular level in two songbird models with different song learning and neuroplasticity characteristics. Our hypothesis is that hormones and the environment induce brain plasticity at least in part through epigenetic changes defined as alterations in gene expression that are self-perpetuating in the absence of the original signal that caused them. Recent evidence indicates that DNA methylation, histone modifications (acetylation, methylation) and noncoding RNAs (miRNA, long ncRNA) may serve as a contributing mechanism in memory formation and storage as well as neuronal plasticity. These mechanisms may be relevant for brain plasticity but also more generally in the control of a variety of clinical conditions such as Alzheimer’s disease, depression, anxiety, schizophrenia and Rett syndrome. Their analysis is thus of broad interest.