Recent evidence suggests that postpartum depression is associated with reduced amygdala (AMY) response to negative stimuli. However, given the anhedonic features of PPD, it is important to consider mothers' brain response specifically to positive infant and to other positive stimuli. Mothers with (n = 28) and without (n = 17) clinically determined PPD (n = 28) viewed smiling pictures of infants (Own and Other), and positive non-infant stimuli (Non-Infant). First, we examined group differences in AMY response across conditions. Next, psychophysiological interaction was used to examine group differences in AMY connectivity across conditions. Connectivity estimates were then correlated with measures of maternal mood and anxiety. PPD mothers, compared to non-PPD mothers, showed overall increased AMY response across conditions in the right AMY. Despite this, PPD mothers demonstrated decreased bilateral AMY-right insular cortex (IC) connectivity as compared to non-PPD mothers when they view Own-Other infants. Furthermore, decreasing AMY-IC connectivity was associated with increasing symptoms of depression and anxiety. These differences were evident only for infant stimuli and did not apply to all positively valenced stimuli. Thus, PPD mothers show altered brain response and connectivity in regions strongly implicated in the processing of socially and emotionally relevant stimuli, as well as interoception and the evaluation of subjective emotional experience.

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Rat dams differ naturally in the level of maternal care they provide to their offspring within the same litter. We explored possible mechanisms of differential maternal care focused on genetic variation. We examined single nucleotide polymorphisms in the glucocorticoid receptor, FK506-binding protein, and serotonin transporter genes in two separate cohorts, and the relationship between differential maternal care received, genotype, and offspring phenotype. Allelic variation in all three genes was significantly associated with levels of maternal care received by offspring and behavioral and endocrine stress responses in adulthood. Differences in pup behavior were also associated with allelic variation in these genes. Together, these results indicate that the dam/pup interaction is dynamic and implicate the genotype of the offspring in influencing the level of maternal care received. They further suggest that some genotypes may have a dampening effect on the impact of maternal care on stress-related phenotypes in adulthood.

In many mammalian species, new mothers show heightened positive responsiveness to infants and their cues when they give birth. As is evident from non‐human and human studies, the amygdala is a brain region implicated in both the maternal and affective neural circuitry, and is involved in processing socioemotionally salient stimuli. In humans, infants are socially salient stimuli to women, and mothers in particular. Neuroimaging studies investigating the maternal response to infant cues have identified infant‐related amygdala function as an important factor in maternal anxiety/depression, in the quality of mothering and in individual differences in the motivation to mother. The present study investigated the effects of maternal status and depression on the subjective affective response and amygdala responsiveness to unfamiliar infants using functional magnetic resonance imaging. Smiling infant pictures were used in a 2 × 2 design comparing four groups of women: mothers and non‐mothers, with and without depression (total of 101 women: postpartum depression [PPD] = 32, non‐PPD = 25, major depression [MDD] = 15, non‐MDD = 29). We undertook an anatomically defined region of interest analysis of the amygdala response for a priori defined group comparisons. We found that mothers rated infants more positively than non‐mothers and non‐mothers rated non‐infant stimuli (scenery) more positively than mothers. In the amygdala, we found that depression elevated response to smiling unfamiliar infants in mothers but had no effect in non‐mothers. Within the depressed groups, mothers (PPD) showed an elevated amygdala response to unfamiliar smiling infants compared to depressed non‐mothers. Hence, our results indicate that women with PPD show an enhanced amygdala response to affectively positive infant pictures but not to affectively positive (but non‐salient) pictures of scenery. Women with depression outside of the postpartum period show no change in amygdala responsiveness to either stimulus categories.