Genetic variants in oxytocin receptor and arginine-vasopressin receptor 1A are associated with the neural correlates of maternal and paternal affection towards their child

There is extensive evidence in animal studies, particularly in vole species (Microtus), that oxytocin (OT) receptor and arginine-vasopressin (AVP) receptor 1a is critical for the regulation of maternal and paternal behavior, respectively. Human studies have gained insight into the relationship between both hormone receptor gene variants and behavior, but not between the variants and the underlying brain activity. To study this, we investigated the association between neural activation of the anterior prefrontal cortex (APFC) in mothers and fathers in response to their child smiling video stimuli to induce the positive affect related to attachment with their child, and genetic variants of OT receptor (OXTR) and AVP receptor 1A (AVPR1A). Overall, 43 mothers and 41 fathers participated, and each parent's child smiling was video recorded. Participants were then genotyped and underwent near-infrared spectroscopy to measure neural activation of the APFC while observing their own child smiling compared with an unfamiliar child. We found that the right inferior APFC was activated in response to child video stimuli in mothers and differential hemispheric activation of the inferior APFC in OXTR rs2254298-G/G mothers compared with -A carrier mothers, but not in fathers. Furthermore, we found a difference in the left inferior APFC activation between AVPR1A RS3-non-334 and -334 carrier fathers, but not mothers. Our results indicate a sex-dependent association between the genetic variants and the inferior APFC activations of maternal and paternal positive affect, analogous to the results reported in voles.