The neural and genetic correlates of satisfying sexual activity in heterosexual pair-bonds

In humans, satisfying sexual activity within a pair-bond plays a significant role in relationship quality and maintenance, beyond reproduction. However, the neural and genetic correlates for this basic species-supporting function, in response to a pair-bonded partner, are unknown.

We examined the neural correlates of oxytocin- (Oxtr rs53576) and vasopressin- (Avpr1a rs3) receptor genotypes with sexual satisfaction and frequency, among a group of individuals in pair-bonds (M relationship length = 4.1 years). Participants were scanned twice (with functional MRI), about 1-year apart, while viewing face images of their spouse and a familiar, neutral acquaintance.

Sex satisfaction scores showed significant interactions with Oxtr and Avpr variants associated with social behaviors in a broad network of regions involved in reward and motivation (ventral tegmental area, substantia nigra [SN], and caudate), social bonding (ventral pallidum), emotion and memory (amygdala/hippocampus), hormone control (hypothalamus); and somatosensory and self-other processing (SII, frontal, and temporal lobe). Sexual frequency interactions also showed activations in the SN and paraventricular hypothalamus for Avpr, and the prefrontal cortex for Oxtr.

Satisfying sexual activity in pair-bonds is associated with activation of subcortical structures that support basic motivational and physiological processes; as well as cortical regions that mediate complex thinking, empathy, and self-other processes highlighting the multifaceted role of sex in pair-bonds. Oxtr and Avpr gene variants may further amplify both basic and complex neural processes for pair-bond conservation and well-being.