Epigenetic mechanisms underlying learning and the inheritance of learned behaviors

• Fear conditioning is an excellent tool to understand epigenetic memory regulation.
• Epigenetic marks in gametes may allow signals to be passed to the next generation.
• Noncoding RNA provides a mechanism by which signals may be transmitted across genomes.
• Epigenetics enhances understanding of gene–environment interactions in psychiatry.

Gene expression and regulation is an important sculptor of the behavior of organisms. Epigenetic mechanisms regulate gene expression not by altering the genetic alphabet but rather by the addition of chemical modifications to proteins associated with the alphabet or of methyl marks to the alphabet itself. Being dynamic, epigenetic mechanisms of gene regulation serve as an important bridge between environmental stimuli and genotype. In this review, we outline epigenetic mechanisms by which gene expression is regulated in animals and humans. Using fear learning as a framework, we then delineate how such mechanisms underlie learning and stress responsiveness. Finally, we discuss how epigenetic mechanisms might inform us about the transgenerational inheritance of behavioral traits that are being increasingly reported.