Natural variation in maternal sensitivity Is reflected in maternal brain responses to infant stimuli

Increasing evidence suggests that discrete neural networks that mediate emotion processing are activated when mothers respond to infant's images or cries. Accumulating data also indicate that natural variation in maternal caregiving behavior is related to maternal oxytocin (OT) levels. However, brain activation to infant cues has not been studied comparing mothers at disparate ends of the "maternal sensitivity" spectrum. Based on observed mother-infant play interaction at 4-6 months postpartum in 80 antenatally recruited mothers, 15 mothers with the highest sensitivity (HSMs) and 15 mothers with the lowest sensitivity (LSMs) were followed at 7-9 months using functional magnetic resonance imaging (fMRI) to examine brain responses to viewing videos of their "own" versus an "unknown" infant in 3 affect states (neutral, happy, and sad). Plasma OT measurements were taken from mothers following play interactions with their infant. Compared with LSMs, HSMs showed significantly greater brain activation in right superior temporal gyrus (STG) in response to own versus unknown neutral infant and to own happy versus neutral control. Changes in brain activation were significantly negatively correlated with plasma OT responses in HSMs mothers. Conversely, compared with HSMs, LSMs showed no significant activation difference in response to own infant separately or in contrast to unknown infant. Activation of STG may index sensitive maternal response to own infant stimuli. Sensitive parenting may have its unique profile in relation to brain responses which can act as biomarkers for future intervention studies that enhance sensitivity of maternal care.