Outdoor noncontact respiratory measurements of unrestricted rhesus macaques (Macaca mulatta) using millimeter-wave radar.

Respiration is an invaluable signal that facilitates the real-time observation of physiological dynamics. In recent years, the advancement of noncontact measurement technology has gained momentum in capturing physiological activities in natural settings. This technology is anticipated to be found not only in humans but also in nonhuman primates. Currently, the predominant noncontact approach for nonhuman animals involves measuring vital signs through subtle variations in skin color. However, this approach is limited when addressing areas of the body covered with hair or when working in outdoor settings under fluctuating sunlight. To overcome this issue, we focused on noncontact respiratory measurements using millimeter-wave radar. Millimeter-wave radar systems, which employ millimeter waves that can penetrate animal fur and estimate respiration-derived periodic body motion, exhibit minimal susceptibility to sunlight interference. Thus, this method shows potential for conducting noncontact vital measurements in natural and outdoor settings. In this study, we validated a millimeter-wave radar methodology for capturing respiration in outdoor-housed rhesus macaques (Macaca mulatta). The radar was positioned beyond the captive enclosure and maintained at a distance >5 m from the target. Millimeter waves were transmitted to the target, and the reflected waves were used to estimate skin surface displacement associated with respiration. The results revealed periodic skin surface displacement, and the estimated respiratory rates weres within the reported range of respiratory rates for rhesus macaques. These results suggest the potential applicability of millimeter-wave radar for noncontact respiration monitoring in outdoor-living macaques without anesthesia or immobilization. The continued advancement of noncontact vital measurement technology will contribute to understanding primate mental and physical dynamics during their daily life.

Intestinal microbiome and maternal mental health: preventing parental stress and enhancing resilience in mothers.

The number of mothers suffering from mental illness is increasing steadily, particularly under conditions of the coronavirus pandemic. The identification of factors that contribute to resilience in mothers is urgently needed to decrease the risks of poor physical and psychological health. We focused on the risk of parenting stress and psychological resilience in healthy mothers with no psychiatric and physical disorders and conducted two studies to examine the relationships between intestinal microbiota, physical condition, and psychological state. Our results showed that alpha diversity and beta diversity of the microbiome are related to high parenting stress risk. Psychological resilience and physical conditions were associated with relative abundances of the genera Blautia, Clostridium, and Eggerthella. This study helps further understand the gut-brain axis mechanisms and supports proposals for enhancing resilience in mothers.

Altered Gut Microbiota Composition Is Associated with Difficulty in Explicit Emotion Regulation in Young Children.

Executive function (EF) consists of explicit emotion regulation (EER) and cognitive control (CC). Childhood EER in particular predicts mental and physical health in adulthood. Identifying factors affecting EER development has implications for lifelong physical and mental health. Gut microbiota (GM) has attracted attention as a potential biomarker for risk of physical and mental problems in adulthood. Furthermore, GM is related to brain function/structure, which plays a crucial role in emotional processing. However, little is known about how GM compositions are associated with the development of emotion regulation in early childhood. Therefore, in this study, we examined 257 children aged 3-4 to investigate links between GM and risk to EF. EF was measured using the Mother-Reported Behavior Rating Inventory of Executive Function-Preschool version. GM composition (alpha/beta diversity and genus abundance) was evaluated using 16S rRNA gene sequencing and compared between EF-risk and non-risk groups. Our results show that children with EER-risk (an index of inhibitory self-control) had a higher abundance of the genera Actinomyces and Sutterella. Although we have not established a direct link between GM and CC risk, our findings indicate that GM of preschoolers is closely associated with emotional processing and that EERrisk children have more inflammation-related bacteria.

Development of the Paternal Brain in Humans throughout Pregnancy.

Previous studies have demonstrated that paternal caregiving behaviors are reliant on neural pathways similar to those supporting maternal care. Interestingly, a greater variability exists in parental phenotypes in men than in women among individuals and mammalian species. However, less is known about when or how such variability emerges in men. We investigated the longitudinal changes in the neural, hormonal, and psychological bases of expression of paternal caregiving in humans throughout pregnancy and the first 4 months of the postnatal period. We measured oxytocin and testosterone, paternity-related psychological traits, and neural response to infant-interaction videos using fMRI in first-time fathers and childless men at three time points (early to mid-pregnancy, late pregnancy, and postnatal). We found that paternal-specific brain activity in prefrontal areas distinctly develops during middle-to-late pregnancy and is enhanced in the postnatal period. In addition, among fathers, the timing of the development of prefrontal brain activity was associated with specific parenting phenotypes.

A multidimensional physical scale is a useful screening test for mild depression associated with childcare in Japanese child-rearing women.

Introduction: Maternal depression is one of the important problems of postpartum women. For its early detection and appropriate treatment, it is necessary to identify women at high risk for depression quickly and easily. Materials and methods: A simple screening scale for depression from physical aspects, the multidimensional physical scale (MDPS), which is a 17-item, self-report, three-step scale (0, 1, 2) according to the theory of Kampo medicine, was developed. The aim of the present study was to develop (n = 785) and validate (n = 350) the MDPS that was designed to rate the risk of depression. The Beck Depression Inventory-Second Edition was used for determination of depression. In the development cohort, the final model was determined using multi-regression logistic analysis. Results: The components of the MDPS for mothers (MDPS-M) were developed, containing the total score of MDPS (0-34 points) and resumption of menstruation or not (-3, 0 points). Receiver-operating characteristic curve analysis of the MDPS-M (-3 to 34) for identifying a high risk of depression showed moderately good discrimination [area under the curve (AUC) = 0.74, 95% confidence interval (CI): 0.70-0.78]. At the cutoff value of MDPS-M (9/10), its sensitivity, specificity, positive predictive value, and negative predictive value were 84.9, 45.7, 36.7, and 89.2%, respectively. External validation of the MDPS-M showed moderately good discrimination (AUC = 0.74, 95% CI: 0.68-0.79) using the same analysis as the development cohort. Conclusion: These results indicate that the MDPS-M is a useful, simple, clinical scale for early identification of mothers at high risk of depression in primary care.

From spontaneous rhythmic engagement to joint drumming: A gradual development of flexible coordination at approximately 24 months of age.

Humans have a flexible and accurate ability to coordinate their movement in time with external rhythms. However, it remains unclear when and how, during their development, human children acquire the ability to adjust tempo and control the timing of their movement toward others. A previous study suggested that such self-regulation of coordination develops at around 18 and 30 months after birth. In this study, we investigated the performance of 24-month-old children and compared their data with those of 18- and 30-month-olds provided in our previous study. In the joint-drumming task, each child was enticed to drum under four conditions [partner: mother or robot; speed: 400 or 600 ms inter-stimulus-interval (ISI)]. The most pivotal test condition was the 600 ms ISI speed condition (slower than children's spontaneous motor tempo in these age groups). We found that from the age of 24 months, children try to slow down their drumming tempo toward the 600 ms ISI speed condition, regardless of the drumming partner. On the other hand, significant timing control toward the onset of the 600 ms ISI condition was observed from the age of 30 months. This implies that both motor and cognitive mechanisms are required for flexible tempo adjustment and accurate synchronization and that these develop gradually among 18-, 24-, and 30-month-olds.

Cognitive flexibility in 12-month-old preterm and term infants is associated with neurobehavioural development in 18-month-olds.

There is growing evidence that preterm children are at an increased risk of poor executive functioning, which underlies behavioural and attention problems. Previous studies have suggested that early cognitive flexibility is a possible predictor of later executive function; however, how it develops in infancy and relates to the later neurobehavioural outcomes is still unclear in the preterm population. Here, we conducted a longitudinal study to investigate oculomotor response shifting in 27 preterm and 25 term infants at 12 months and its relationship with general cognitive development and effortful control, which is a temperamental aspect closely associated with executive function, at 18 months. We found that moderate to late preterm and term infants significantly inhibited previously rewarded look responses, while very preterm infants did not show significant inhibition of perseverative looking at 12 months. Moreover, lower inhibition of perseverative looking was significantly associated with lower general cognitive development and attentional shifting at 18 months. These findings suggest that the early atypical patterns of oculomotor response shifting may be a behavioural marker for predicting a higher risk of negative neurobehavioural outcomes, including attention-related problems in preterm children.

Longitudinal assessment of social attention in preterm and term infants: Its relation to social communication and language outcome.

Preterm birth has been reported to be associated with an increased risk of social communication and language problems. Recently, we found that preterm infants showed atypical patterns of social attention compared with term infants. However, it is still unknown how social attention develops and whether the individual differences are associated with developmental outcomes for social communication and language in preterm infants. The social attention of preterm and term infants at 6, 12, and 18 months was investigated using two types of social attention tasks (human-geometric preference task and gaze-following task). The Modified Checklist for Autism in Toddlers (M-CHAT) and the MacArthur Communicative Development Inventory adapted for Japanese were measured at 18 months. We found that compared with term infants, preterm infants spent less time looking toward dynamic human images and followed another's gaze directions less frequently through 6, 12, and 18 months. Moreover, hierarchical multiple regression analysis revealed that less preference for dynamic human images and gaze-following abilities was associated with high M-CHAT and low language scores in preterm and term infants, respectively. These findings suggest that birth status affects development of social attention through 18 months and individual differences in social attention reflect differences in social communication and language outcomes.

The early development of tempo adjustment and synchronization during joint drumming: A study of 18- to 42-month-old children.

Humans have a unique ability to coordinate their rhythmic behaviors with those of others. Previous studies have demonstrated the early development of spontaneous responses to external rhythmic stimuli; however, there is little evidence regarding when and how infants begin to adjust their movement tempo and synchronize it with that of others, due to the difficulty of detecting continuous rhythmic movements of infants in a laboratory setting. In the current study, we analyzed children in age-groups of 18, 30, and 42 months and adapted a joint-drumming task used by Kirschner and Tomasello (Journal of Experimental Child Psychology, 2009, 102, 299-314). The children were enticed to play the drum under four conditions (Speed: 400 or 600 ms ISI; Partner: mother or robot). The results demonstrated that children's ability to adjust their tempo and synchronize with that of 600 ms ISI, which is slower than the spontaneous motor tempo of children at these ages, starts to develop at around 30-month-olds. We also found early evidence of this ability in 18-month-old infants who drummed with their mother. These findings indicate that children's ability for rhythmic coordination develops dynamically between 18 and 30 months of age, and a child's social partner plays an important role in facilitating this development.

Development of the paternal brain in expectant fathers during early pregnancy.

The human parenting brain network mediates caregiving behaviors. When exposed to the stimuli of their infants, compared with non-parents, both fathers and mothers exhibit distinct patterns of neural activation. As human males, relative to females, do not undergo robust physiological changes during pregnancy, when and how the paternal brain networks begin to form remains unclear. Thus, using functional MRI, we examined brain activation in response to infant-interaction videos in two groups, childless males and first-time expectant fathers during their partners' early pregnancy before remarkable changes in their partners' appearances commenced. Multivoxel pattern analysis revealed that expectant fathers' left anterior insula and inferior frontal gyrus showed incipient changes in response to parenthood during early pregnancy. Furthermore, these changes were associated with several paternal traits, such as a negative image toward parenting. Such external factors might influence the paternal brain's development during early pregnancy.

Interoception is associated with the impact of eye contact on spontaneous facial mimicry.

Interoception (perception of one's own physiological state) has been suggested to underpin social cognition, although the mechanisms underlying this association remain unclear. The current study aimed to elucidate the relationship between interoception and two factors underlying social cognition: self-other boundary and sensitivity to social cues. We measured performance in a heartbeat perception task as an index of interoceptive accuracy (IAc), the frequency of spontaneous facial mimicry (SFM) as an index of self-other boundary, and the degree of the effect of eye contact on SFM (difference in SFM between conditions in which models' eyes were directed to and averted from participants) as an index of social-cue sensitivity, and tested correlations among these measures. The results revealed that IAc and SFM were positively correlated only in the direct gaze condition. The extent of the effect of eye contact on SFM (difference in frequency between direct vs. averted conditions) was positively correlated with IAc. These overall findings were also observed in separate analyses of male and female participant groups, supporting the robustness of the findings. The results suggest that interoception is related to sensitivity to social cues, and may also be related to the self-other boundary with modulation by social context.

Breastfeeding dynamically changes endogenous oxytocin levels and emotion recognition in mothers.

Breastfeeding behaviours can significantly change mothers' physiological and psychological states. The hormone oxytocin may mediate breastfeeding and mothers' emotion recognition. This study examined the effects of endogenous oxytocin fluctuation via breastfeeding on emotion recognition in 51 primiparous mothers. Saliva oxytocin was assessed before and after the manipulation (breastfeeding or holding an infant), and emotion recognition tasks were conducted. Among mothers who breastfed daily, mothers with more increased levels of oxytocin after breastfeeding showed more reduced negative recognition and enhanced positive recognition of adult facial expressions. These oxytocin functions accompanying breastfeeding may support continued nurturing behaviours and also affect the general social cognition of other adults beyond any specific effect on infants.

Demystifying infant vocal imitation: The roles of mouth looking and speaker's gaze.

Vocal imitation plays a fundamental role in human language acquisition from infancy. Little is known, however, about how infants imitate other's sounds. We focused on three factors: (a) whether infants receive information from upright faces, (b) the infant's observation of the speaker's mouth and (c) the speaker directing their gaze towards the infant. We recorded the eye movements of 6-month-olds who participated in experiments watching videos of a speaker producing vowel sounds. We found that an infants' tendency to vocally imitate such videos increased as a function of (a) seeing upright rather than inverted faces, (b) their increased looking towards the speaker's mouth and (c) whether the speaker directed their gaze towards, rather than away from infants. These latter findings are consistent with theories of motor resonance and natural pedagogy respectively. New light has been shed on the cues and underlying mechanisms linking infant speech perception and production.

Audiovisual speech perception and language acquisition in preterm infants: A longitudinal study.

BACKGROUND: Preterm infants have a higher risk of language delay throughout childhood. The ability to integrate audiovisual speech information is associated with language acquisition in term infants; however, the relation is still unclear in preterm infant. AIM AND METHODS: This study longitudinally investigated visual preference for audiovisual congruent and incongruent speech during a preferential looking task using eye-tracking in preterm and term infants at 6, 12, and 18 months of corrected age. The infants' receptive and expressive vocabulary at 12 and 18 months were obtained by parent report, using the Japanese MacArthur Communicative Development Inventory. RESULTS: We found that preterm infants did not clearly show visual preference for the congruent audiovisual display at any age, whereas term infants looked at the congruent audiovisual display longer than the incongruent audiovisual display at 6 and 18 months. Preterm infants' receptive and expressive vocabulary scores were lower than those of term infants at 12 and 18 months. Furthermore, the proportion of looking time toward the congruent audiovisual display at 6 months was positively correlated with receptive vocabulary scores at 12 and 18 months for both groups. CONCLUSIONS: These findings suggest that better audiovisual speech perception abilities are one factor that results in better language acquisition in preterm as well as term infants. Early identification of behaviors associated with later language in preterm infants may contribute to planning intervention for developmental problems.

Maternal nurturing experience affects the perception and recognition of adult and infant facial expressions.

The perception and recognition of facial expressions are crucial for parenting. This study investigated whether and how maternal nurturing experience and trait anxiety influence the perception and recognition of infant and adult facial expressions. This was assessed by comparing the performance of primiparous mothers (n = 25) and non-mothers (n = 28) on an emotional face perception task. Trait anxiety was measured using the Japanese version of the State-Trait Anxiety Inventory (STAI). We found that mothers had higher recognition accuracy for facial expressions, but only of adults, not infants. Moreover, as trait anxiety increased, so did mothers' sensitivity in perceiving facial expressions of both infants and adults. These findings suggest that maternal nurturing experience does enhance the recognition of adult emotional expressions, and an optimal level of maternal trait anxiety may enhance mothers' sensitivity toward infants' and adults' emotional signals.

The integration of audio-tactile information is modulated by multimodal social interaction with physical contact in infancy.

Interaction between caregivers and infants is multimodal in nature. To react interactively and smoothly to such multimodal signals, infants must integrate all these signals. However, few empirical infant studies have investigated how multimodal social interaction with physical contact facilitates multimodal integration, especially regarding audio - tactile (A-T) information. By using electroencephalogram (EEG) and event-related potentials (ERPs), the present study investigated how neural processing involved in A-T integration is modulated by tactile interaction. Seven- to 8-months-old infants heard one pseudoword both whilst being tickled (multimodal 'A-T' condition), and not being tickled (unimodal 'A' condition). Thereafter, their EEG was measured during the perception of the same words. Compared to the A condition, the A-T condition resulted in enhanced ERPs and higher beta-band activity within the left temporal regions, indicating neural processing of A-T integration. Additionally, theta-band activity within the middle frontal region was enhanced, which may reflect enhanced attention to social information. Furthermore, differential ERPs correlated with the degree of engagement in the tickling interaction. We provide neural evidence that the integration of A-T information in infants' brains is facilitated through tactile interaction with others. Such plastic changes in neural processing may promote harmonious social interaction and effective learning in infancy.

Chimpanzees recognize their own delayed self-image.

Unlike mirror self-recognition, recognizing one's own image in delayed video footage may indicate the presence of a concept of self that extends across time and space. While humans typically show this ability around 4 years of age, it is unknown whether this capacity is found in non-human animals. In this study, chimpanzees performed a modified version of the mark test to investigate whether chimpanzees could remove stickers placed on the face and head while watching live and delayed video images. The results showed that three of five chimpanzees consistently removed the mark in delayed-viewing conditions, while they removed the stickers much less frequently in control video conditions which lacked a link to their current state. These findings suggest that chimpanzees, like human children at the age of 4 years and more, can comprehend temporal dissociation in their concept of self.

Fundamental Frequency Variation of Neonatal Spontaneous Crying Predicts Language Acquisition in Preterm and Term Infants.

Spontaneous cries of infants exhibit rich melodic features (i.e., time variation of fundamental frequency [F0 ]) even during the neonatal period, and the development of these characteristics might provide an essential base for later expressive prosody in language. However, little is known about the melodic features of spontaneous cries in preterm infants, who have a higher risk of later language-related problems. Thus, the present study investigated how preterm birth influenced melodic features of spontaneous crying at term-equivalent age as well as how these melodic features related to language outcomes at 18 months of corrected age in preterm and term infants. At term, moderate-to-late preterm (MLP) infants showed spontaneous cries with significantly higher F0 variation and melody complexity than term infants, while there were no significant differences between very preterm (VP) and term infants. Furthermore, larger F0 variation within cry series at term was significantly related to better language and cognitive outcomes, particularly expressive language skills, at 18 months. On the other hand, no other melodic features at term predicted any developmental outcomes at 18 months. The present results suggest that the additional postnatal vocal experience of MLP preterm infants increased F0 variation and the complexity of spontaneous cries at term. Additionally, the increases in F0 variation may partly reflect the development of voluntary vocal control, which, in turn, contributes to expressive language in infancy.