DNA Methylation of the Oxytocin Receptor Gene Maps Increases in Conditioned Learning Rates at the Late Positive Potential

Associative learning is a fundamental building block of information acquisition. Organisms learn from environmental cues to detect signals that predict reward or punishment, and update beliefs on how to respond accordingly. Demands on the human brain are uniquely complex, requiring advanced abilities to recognize, manipulate and respond to socially relevant information. This includes the ability to construct representations of environmental contingencies predicting safety and threat. Individual differences contribute to the ability to flexibly learn and update responses appropriately. Here we investigate a potential biological feature for capturing individual differences in associative learning, epigenetic modification (i.e., DNA methylation) of the oxytocin receptor (OXTR). Leveraging the sensitivity of slow-wave event-related potentials, we provide new evidence that OXTR methylation (OXTRm) is theoretically relevant for understanding electrophysiological brain function as it pertains to human associative learning. This work demonstrates modulation of associative learning rates as a function of OXTRm indexed by the late positive potential (LPP). The results suggest that oxytocin may play a primitive role in signaling survival behaviors (i.e., approaching appetitive resources, avoiding aversive environments). By integrating theoretical perspectives from psychology, neuroscience, and epigenetics, this work enriches understanding of how the brain reflects oxytocin's allostatic functionality, by investigating its manifestation of fear acquisition embedded in electrophysiological conditioned responses.