Physical presence of spouse enhances brain-to-brain synchrony in co-parenting couples.

Co-parenting spouses who live together remain in close physical proximity to each other and regularly engage in reciprocal social interactions in joint endeavors to coordinate their caregiving. Although bi-parental rearing is a common occurrence in humans, the influence of the physical presence of a co-parenting spouse on parental brain responses remains largely unknown. Synchrony is conceptualized as the matching of behavioral and physiological signals between two individuals. In this study, we examined how the presence of a co-parenting spouse influences brain-to-brain synchrony when attending to salient infant and adult vocalizations. We hypothesized that brain-to-brain synchrony would be greater in the presence of a spousal partner. Functional Near-infrared Spectroscopy (fNIRS) was used on 24 mother-father dyads (N = 48) to measure prefrontal cortical (PFC) activities while they listened to infant and adult vocalizations in two conditions, together (in the same room at the same time) and separately (in different rooms at different times). Couples showed greater synchrony in the together condition; when comparing fNIRS data between true couples and randomly matched controls, this synchronous effect was only seen in true couples, indicating a unique effect of spousal co-regulation toward salient stimuli. Our results indicate that the physical presence of the spouse might establish synchrony in attentional regulation mechanisms toward socially relevant stimuli. This finding holds implications for the role of the co-parenting spouse in influencing social and parental brain mechanisms.

Adults' implicit associations to infant positive and negative acoustic cues: Moderation by empathy and gender.

In this study a novel auditory version of the Single Category Implicit Association Test (SC-IAT-A) was developed to investigate (a) the valence of adults' associations to infant cries and laughs, (b) moderation of implicit associations by gender and empathy, and (c) the robustness of implicit associations controlling for auditory sensitivity. Eighty adults (50% females) were administered two SC-IAT-As, the Empathy Quotient, and the Weinstein Noise Sensitivity Scale. Adults showed positive implicit associations to infant laugh and negative ones to infant cry; only the implicit associations with the infant laugh were negatively related to empathy scores, and no gender differences were observed. Finally, implicit associations to infant cry were affected by noise sensitivity. The SC-IAT-A is useful to evaluate the valence of implicit reactions to infant auditory cues and could provide fresh insights into understanding processes that regulate the quality of adult-infant relationships.

Infant Cries Rattle Adult Cognition.

The attention-grabbing quality of the infant cry is well recognized, but how the emotional valence of infant vocal signals affects adult cognition and cortical activity has heretofore been unknown. We examined the effects of two contrasting infant vocalizations (cries vs. laughs) on adult performance on a Stroop task using a cross-modal distraction paradigm in which infant distractors were vocal and targets were visual. Infant vocalizations were presented before (Experiment 1) or during each Stroop trial (Experiment 2). To evaluate the influence of infant vocalizations on cognitive control, neural responses to the Stroop task were obtained by measuring electroencephalography (EEG) and event-related potentials (ERPs) in Experiment 1. Based on the previously demonstrated existence of negative arousal bias, we hypothesized that cry vocalizations would be more distracting and invoke greater conflict processing than laugh vocalizations. Similarly, we expected participants to have greater difficulty shifting attention from the vocal distractors to the target task after hearing cries vs. after hearing laughs. Behavioral results from both experiments showed a cry interference effect, in which task performance was slower with cry than with laugh distractors. Electrophysiology data further revealed that cries more than laughs reduced attention to the task (smaller P200) and increased conflict processing (larger N450), albeit differently for incongruent and congruent trials. Results from a correlation analysis showed that the amplitudes of P200 and N450 were inversely related, suggesting a reciprocal relationship between attention and conflict processing. The findings suggest that cognitive control processes contribute to an attention bias to infant signals, which is modulated in part by the valence of the infant vocalization and the demands of the cognitive task. The findings thus support the notion that infant cries elicit a negative arousal bias that is distracting; they also identify, for the first time, the neural dynamics underlying the unique influence that infant cries and laughs have on cognitive control.

Three physiological responses in fathers and non-fathers' to vocalizations of typically developing infants and infants with Autism Spectrum Disorder.

Children with ASD, even before receiving a formal diagnosis, express atypical patterns of distress vocalizations (namely, episodes of crying). Their cries have higher fundamental frequencies, shorter inter-bout pauses, and fewer utterances. Cries of children with ASD are also perceived differently from other cries, and these perceptual differences may alter parent-infant interaction. This study assessed multiple physiological responses in fathers and non-fathers to atypical distress vocalizations (cries of children with ASD), acoustically matched typical distress vocalizations (cries of typically developing children), and positive vocalizations (laughter of typically developing children). The experimental procedures were designed to measure how components of the autonomic nervous system respond to typical and atypical infant vocalizations. Three convergent methodologies (Galvanic Skin Response-GSR; cardiac dynamics via Inter-Beat Interval-IBI; right hand temperature change-RHTC) were performed on two groups with contrasting caregiving experience: fathers of typically developing children (n=10) and non-fathers (n=10). Inferential statistical analysis compared the two groups (fathers, non-fathers) and three stimulus types (ASD cry, typical cry, laughter) for the three measures (GSR, IBI, RHTC). Both fathers and non-fathers showed greater negative responses (increased GSR) to ASD cries compared to typical cries and laughter. Fathers showed higher IBI and greater temperature increases (RHTC) than non-fathers while listening to typical and atypical cries. Fathers and non-fathers showed more emotional arousal mediated by sympathetic activation while listening to cries of children with ASD. Fathers were calmer and acted more promptly than non-fathers while listening to typical cries, perhaps because the fathers had more experience in caring for crying infants. These findings point to similarities and differences in fathers' and non-fathers' physiological responsiveness to cries of children with ASD and might guide specific intervention programs for parents of children at risk of ASD.

Sex differences in directional brain responses to infant hunger cries.

Infant cries are a critical survival mechanism that draw the attention of adult caregivers, who can then satisfy the basic needs of otherwise helpless infants. Here, we used functional neuroimaging to determine the effects of infant hunger cries on the brain activity of adults who were in a cognitively nondemanding mental state of awake rest. We found that the brains of men and women, independent of parental status (parent or nonparent), reacted differently to infant cries. Specifically, the dorsal medial prefrontal and posterior cingulate areas, known to be involved in mind wandering (the stream of thought typical of awake rest), remained active in men during exposure to infant cries, whereas in women, activity in these regions decreased. These results show sex-dependent modulation of brain responses to infant requests to be fed, and specifically, they indicate that women interrupt mind wandering when exposed to the sounds of infant hunger cries, whereas men carry on without interruption.

Differential brain responses to cries of infants with autistic disorder and typical development: an fMRI study.

This study used fMRI to measure brain activity during adult processing of cries of infants with autistic disorder (AD) compared to cries of typically developing (TD) infants. Using whole brain analysis, we found that cries of infants with AD compared to those of TD infants elicited enhanced activity in brain regions associated with verbal and prosodic processing, perhaps because altered acoustic patterns of AD cries render them especially difficult to interpret, and increased activity in brain regions associated with emotional processing, indicating that AD cries also elicit more negative feelings and may be perceived as more aversive and/or arousing. Perceived distress engendered by AD cries related to increased activation in brain regions associated with emotional processing. This study supports the hypothesis that cry is an early and meaningful anomaly displayed by children with AD. It could be that cries associated with AD alter parent-child interactions much earlier than the time that reliable AD diagnosis normally occurs.

Maternal zinc supplementation during pregnancy affects autonomic function of Peruvian children assessed at 54 months of age.

Maternal prenatal zinc supplementation improved fetal autonomic regulation in a nutrient-deficient population in Peru. To evaluate whether differences in autonomic regulation existed in early childhood, we studied 165 children from a zinc supplementation trial (80% of original sample) as part of a comprehensive evaluation at age 54 mo. Electrocardiogram (ECG) data were collected from the children at rest and while they underwent a cognitive testing battery following a standardized protocol. Of these, 79 were born to mothers receiving 25 mg/d zinc in addition to 60 mg/d iron and 250 µg/d folic acid during pregnancy, and 86 were born to mothers receiving iron and folic acid only. Derived cardiac measures included heart period (HP), range, HP variability (HPV), mean square of successive differences (MSSD), and a measure of vagal tone (V). Children in the zinc supplementation group had greater HP (i.e. slower heart rate), greater range, higher time-independent (HPV) and time-dependent (MSSD) variability in HP, and higher V (P < 0.05) during baseline. Analyses conducted across the cognitive testing period revealed similar effects of prenatal zinc supplementation on cardiac patterns. Concurrent child zinc plasma concentration was also associated with longer HP, greater variability, and marginally higher range and V (P < 0.10). Differences in cardiac patterns due to prenatal zinc supplementation were detectable in children at 54 mo of age during conditions of both rest and challenge, indicating that supplementing zinc-deficient pregnant women has beneficial long-term consequences for neural development associated with autonomic regulation.

Maternal gestational zinc supplementation does not influence multiple aspects of child development at 54 mo of age in Peru.

BACKGROUND: Zinc is necessary for central nervous system development, and maternal zinc status has been associated with developmental differences in offspring. OBJECTIVE: The objective was to evaluate differences in cognitive, social, and behavioral function in Peruvian children at 54 mo of age whose mothers participated during pregnancy in a zinc supplementation trial. DESIGN: We attempted to follow up 205 children from a prenatal zinc supplementation trial and present data on 184 (90%) children-86 whose mothers took 25 mg zinc/d in addition to 60 mg iron and 250 microg folic acid and 98 whose mothers took iron and folic acid only. Following a standardized protocol, we assessed children's intelligence, language and number skills, representational ability, interpersonal understanding, and adaptive behavior and behavioral adjustment. We also assessed aspects of the mother (eg, age, education, verbal intelligence, stresses, and social support in parenting) and the home environment [HOME (Home Observation for the Measurement of the Environment) inventory]. RESULTS: No differences were observed between any of the tests used to characterize cognitive, social, or behavioral development (P > 0.05). Child sex, parity, or treatment compliance did not modify the effects of supplementation on any outcomes. CONCLUSION: The addition of zinc to prenatal supplements did not influence developmental outcomes in Peruvian children when assessed at 4.5 y of age.