Evidence for a Caregiving Instinct: Rapid Differentiation of Infant from Adult Vocalizations Using Magnetoencephalography.

Crying is the most salient vocal signal of distress. The cries of a newborn infant alert adult listeners and often elicit caregiving behavior. For the parent, rapid responding to an infant in distress is an adaptive behavior, functioning to ensure offspring survival. The ability to react rapidly requires quick recognition and evaluation of stimuli followed by a co-ordinated motor response. Previous neuroimaging research has demonstrated early specialized activity in response to infant faces. Using magnetoencephalography, we found similarly early (100-200 ms) differences in neural responses to infant and adult cry vocalizations in auditory, emotional, and motor cortical brain regions. We propose that this early differential activity may help to rapidly identify infant cries and engage affective and motor neural circuitry to promote adaptive behavioral responding, before conscious awareness. These differences were observed in adults who were not parents, perhaps indicative of a universal brain-based "caregiving instinct."

Interpreting infant emotional expressions: Parenthood has differential effects on men and women.

Interpreting and responding to an infant's emotional cues is a fundamental parenting skill. Responsivity to infant cues is frequently disrupted in depression, impacting negatively on child outcomes, which underscores its importance. It is widely assumed that women, and in particular mothers, show greater attunement to infants than do men. However, empirical evidence for sex and parental status effects, particularly in relation to perception of infant emotion, has been lacking. In this study, men and women with and without young infants were asked to rate valence in a range of infant facial expressions, on a scale of very positive to very negative. Results suggested complex interaction effects between parental status, sex, and the facial expression being rated. Mothers provided more positive ratings of the happy expressions and more extreme ratings of the intense emotion expressions than fathers, but non-mothers and non-fathers did not. Low-level depressive symptoms were also found to correlate with more negative ratings of negative infant facial expressions across the entire sample. Overall, these results suggest that parental status might have differential effects on men and women's appraisal of infant cues. Differences between fathers' and mothers' perceptions of infant emotion might be of interest in understanding variance in interaction styles, such as proportion of time spent in play.

Duration of motherhood has incremental effects on mothers' neural processing of infant vocal cues: a neuroimaging study of women.

The transition to motherhood, and the resultant experience of caregiving, may change the way women respond to affective, infant signals in their environments. Nonhuman animal studies have robustly demonstrated that mothers process both infant and other salient signals differently from nonmothers. Here, we investigated how women with and without young infants respond to vocalisations from infants and adults (both crying and neutral). We examined mothers with infants ranging in age (1-14 months) to examine the effects of duration of maternal experience. Using functional magnetic resonance imaging, we found that mothers showed greater activity than nonmothers to vocalisations from adults or infants in a range of cortical regions implicated in the processing of affective auditory cues. This main effect of maternal status suggests a general difference in vocalisation processing across infant and adult sounds. We found that a longer duration of motherhood, and therefore more experience with an infant, was associated with greater infant-specific activity in key parental brain regions, including the orbitofrontal cortex and amygdala. We suggest that these incremental differences in neural activity in the maternal brain reflect the building of parental capacity over time. This is consistent with conceptualizations of caregiving as a dynamic, learning process in humans.