Event-related potentials elicited in mothers by their own and unfamiliar infants’ faces with crying and smiling expression

EEG responses to infant faces in young adults can be influenced by the quality of early care experiences with caregivers

BACKGROUND

The quality of early experiences with caregivers affects individual adjustment and can modulate adults' responses to salient social stimuli, like infant faces. However, in the framework of Interpersonal Acceptance-Rejection Theory (IPARTheory), no research to date has examined whether early experiences of acceptance or rejection from caregivers are associated with individual differences in the electrophysiological (EEG) responses to infant faces.

OBJECTIVE

This study examined the associations between the perceived quality of care during childhood and the behavioral and EEG responses to infant and adult faces in non-parent young adults.

METHODS

N = 60 non-parent young adults (30 males; 30 females) completed an Emotion Recognition task displaying emotional and unemotional infant and adult faces during an EEG recording. Memories of past care experiences with mothers and fathers were collected using the short form version of the Parental Acceptance-Rejection scale.

RESULTS

At the behavioral level, slower Reaction Times (RTs) in recognizing all faces were related to higher levels of perceived maternal rejection in young adults; in particular, males who reported higher levels of maternal rejection displayed longer RTs in recognizing faces compared to females. At the neurophysiological level, as the level of perceived paternal rejection increased, the N170 amplitude to infant faces increased. Females who reported higher levels of paternal rejection, compared to males, had a larger increase in the N170 amplitude and a larger decrease in the LPP amplitude in response to emotional faces.

CONCLUSIONS

While a higher perception of maternal rejection hindered the behavioral responses of adults in recognizing faces, those who felt more rejected by their own father during childhood showed an enhanced N170 amplitude to infant faces. This might reflect a greater need for discrimination resources, at a very early stage of infant face processing, in those adults who perceived higher levels of paternal rejection. Adults' sex modulated the associations found at the behavioral and neurophysiological levels. Overall, our findings extended the IPARTheory postulates that being neglected during childhood might trigger perceptual changes in adults, hindering the elaboration of social cues like infant and adult faces at different levels.

Mothers' and fathers' neural responses toward gender-stereotype violations by their own children

Gender stereotypes facilitate people's processing of social information by providing assumptions about expected behaviors and preferences. When gendered expectations are violated, people often respond negatively, both on a behavioral and neural level. Little is known about the impact of family kinship on the behavioral and neural reactions to gender-stereotype violations. Therefore, we examined whether parents show different responses when gender stereotypes are violated by their own children vs unknown children. The sample comprised 74 Dutch families with a father (Mage = 37.54), mother (Mage = 35.83), son, and daughter aged 3-6 years. Electroencephalography measurements were obtained while parents viewed pictures of their own and unknown children paired with toy or problem behavior words that violated or confirmed gender stereotypes. In half of the trials, parents evaluated the appropriateness of toy-gender and behavior-gender combinations. Parents showed stronger late positive potential amplitudes toward gender stereotype-violating behaviors by own children compared to unknown children. Moreover, parents' P1 responses toward gender stereotype-violating child behaviors were stronger for boys than for girls and for parents who evaluated gender-stereotype violations as less appropriate than gender-stereotype confirmations. These findings indicated that gender-stereotype violations by parents' own children are particularly salient and viewed as less appropriate than gender-stereotype confirmations.

Longitudinal changes in attention bias to infant crying in primiparous mothers

Introduction

Infant stimuli attract caregiver attention and motivate parenting behavior. Studies have confirmed the existence of attentional bias toward infant face stimuli; however, relatively little is known about whether attentional bias exists for infant cry stimuli, which are as important as faces in child-rearing situations. Furthermore, scarce longitudinal evidence exists on how attentional bias toward infant crying changes through the postpartum period.

Methods

In the present study, we conducted an experiment to assess bias toward infant crying at two postpartum time points: at Time 1 (Mean = 75.24 days), 45 first-time mothers participated and at Time 2 (Mean = 274.33 days), 30 mothers participated. At both time points, the mothers participated in a Stroop task with infant crying and white noise as the stimuli. They were instructed to answer the color out loud as quickly and accurately as possible, while ignoring the sound. Four types of audio stimuli were used in this task (the cry of the mother's own infant, the cry of an unfamiliar infant, white noise matched to the cry of the mother's own infant, and white noise matched to the cry of an unfamiliar infant), one of which was presented randomly before each trial. Response time and the correct response rate for each condition were the dependent variables.

Results

For response time, the main effect of familiarity was significant, with longer response times when the participant's infant's cry was presented. In addition, response times were lower at Time 2 than at Time 1 in some conditions in which crying was presented.

Discussion

The results suggest that mothers may be less disturbed by infant crying as they gain more experience. Elucidating the characteristics of postpartum mothers' changes in cognitive performance related to infants' cries would be useful in fundamental and applied research to understand the process of parents' adaptation to parenting.

Racial disparities in EEG research and their implications for our understanding of the maternal brain

Racial disparities in maternal health are alarming and persistent. Use of electroencephalography (EEG) and event-related potentials (ERPs) to understand the maternal brain can improve our knowledge of maternal health by providing insight into mechanisms underlying maternal well-being, including implications for child development. However, systematic racial bias exists in EEG methodology-particularly for Black individuals-and in psychological and health research broadly. This paper discusses these biases in the context of EEG/ERP research on the maternal brain. First, we assess the racial/ethnic diversity of existing ERP studies of maternal neural responding to infant/child emotional expressions, using papers from a recent meta-analysis, finding that the majority of mothers represented in this research are of White/European ancestry and that the racially and ethnically diverse samples that are present are limited in terms of geography. Therefore, our current knowledge base in this area may be biased and not generalizable across racially diverse mothers. We outline factors underlying this problem, beginning with the racial bias in EEG equipment that systematically excludes individuals of African descent, and also considering factors specific to research with mothers. Finally, we highlight recent innovations to EEG hardware to better accommodate diverse hairstyles and textures, and other important steps to increase racial and ethnic representativeness in EEG/ERP research with mothers. We urge EEG/ERP researchers who study the maternal brain-including our own research group-to take action to increase racial diversity so that this research area can confidently inform understanding of maternal health and contribute to minimizing maternal health disparities.

Adult attachment is related to maternal neural response to infant cues: an ERP study

Maternal attachment security is an important predictor of caregiving . However, little is known regarding the neurobiological mechanisms by which attachment influences processing of infant cues, a critical component of caregiving. We examined whether attachment security, measured by the Adult Attachment Interview, might relate to neural responses to infant cues using event-related potentials. Secure (n=35) and insecure (n=24) mothers viewed photographs of infant faces and heard recordings of infant vocalizations while electroencephalography was recorded. We examined initial processing of infant faces (N170) and cries (N100), and attentional allocation to infant faces and cries (P300). Secure mothers were significantly faster than insecure mothers to orient to infant cries (N100), structurally encode their own infant's face (N170), and attend to infant faces (P300). These differences may elucidate mechanisms underlying how attachment may shape neural processing of infant cues and highlight the use ofsocial neuroscientific approaches in examining clinically relevant aspects of attachment.

Functional near-infrared spectroscopy is a useful tool for multi-perspective psychobiological study of neurophysiological correlates of parenting behaviour

The quality of the relationship between caregiver and child has long-term effects on the cognitive and socio-emotional development of children. A process involved in human parenting is the bio-behavioural synchrony that occurs between the partners in the relationship during interaction. Through interaction, bio-behavioural synchronicity allows the adaptation of the physiological systems of the parent to those of the child and promotes the positive development and modelling of the child's social brain. The role of bio-behavioural synchrony in building social bonds could be investigated using functional near-infrared spectroscopy (fNIRS). In this paper we have (a) highlighted the importance of the quality of the caregiver-child relationship for the child's cognitive and socio-emotional development, as well as the relevance of infantile stimuli in the activation of parenting behaviour; (b) discussed the tools used in the study of the neurophysiological substrates of the parental response; (c) proposed fNIRS as a particularly suitable tool for the study of parental responses; and (d) underlined the need for a multi-systemic psychobiological approach to understand the mechanisms that regulate caregiver-child interactions and their bio-behavioural synchrony. We propose to adopt a multi-system psychobiological approach to the study of parental behaviour and social interaction.

Processing children's faces in the parental brain: A meta-analysis of ERP studies

Event-related potentials (ERPs) are an excellent tool for investigating parental neural responses to child stimuli. Using meta-analysis, we quantified the results of available studies reporting N170 or LPP/P3 ERP responses to children's faces, targeting three questions: 1) Do parents and non-parents differ in ERP responses to child faces? 2) Are parental ERP responses larger to own vs. unfamiliar child faces? 3) Are parental ERP responses to child faces associated with indicators of parenting quality, such as observed parental sensitivity? Across 23 studies (N = 1035), key findings showed 1) larger N170 amplitudes to child faces in parents than in non-parents (r = 0.19), 2) larger LPP/P3 responses to own vs. unfamiliar child faces in parents (r = 0.19), and 3) positive associations between parental LPP/P3 responses to child faces and parenting quality outcomes (r = 0.15). These results encourage further research particularly with the LPP/P3 to assess attentional-motivational processes of parenting, but also highlight the need for larger samples and more systematic assessments of associations between ERPs and parenting.

Advancing the RDoC initiative through the assessment of caregiver social processes

The relationships infants and young children have with their caregivers are fundamental to their survival and well-being. Theorists and researchers across disciplines have attempted to describe and assess the variation in these relationships, leading to a general acceptance that caregiving is critical to understanding child functioning, including developmental psychopathology. At the same time, we lack consensus on how to assess these fundamental relationships. In the present paper, we first review research documenting the importance of the caregiver-child relationship in understanding environmental risk for psychopathology. Second, we propose that the National Institute of Mental Health's Research Domain Criteria (RDoC) initiative provides a useful framework for extending the study of children's risk for psychopathology by assessing their caregivers' social processes. Third, we describe the units of analysis for caregiver social processes, documenting how the specific subconstructs in the domain of social processes are relevant to the goal of enhancing knowledge of developmental psychopathology. Lastly, we highlight how past research can inform new directions in the study of caregiving and the parent-child relationship through this innovative extension of the RDoC initiative.

Infants' neutral facial expressions elicit the strongest initial attentional bias in adults: Behavioral and electrophysiological evidence

Recent studies that used adult faces as the baseline have revealed that attentional bias toward infant faces is the strongest for neutral expressions than for happy and sad expressions. However, the time course of the strongest attentional bias toward infant neutral expressions is unclear. To clarify this time course, we combined a behavioral dot-probe task with electrophysiological event-related potentials (ERPs) to measure adults' responses to infant and adult faces with happy, neutral, and sad expressions derived from the same face. The results indicated that compared with the corresponding expressions in adult faces, attentional bias toward infant faces with various expressions resulted in different patterns during rapid and prolonged attention stages. In particular, first, neutral expressions in infant faces elicited greater behavioral attentional bias and P1 responses than happy and sad ones did. Second, sad expressions in infant faces elicited greater N170 responses than neutral and happy ones did; notably, sad expressions elicited greater N170 responses in the left hemisphere in women than in men. Third, late positive potential (LPP) responses were greater for infant faces than for adult faces under each expression condition. Thus, we propose a three-stage model of attentional allocation patterns that reveals the time course of attentional bias toward infant faces with various expressions. This model highlights the prominent role of neutral facial expressions in the attentional bias toward infant faces.

Imagining the baby: Neural reactivity to infant distress and mind-mindedness in expectant parents

Neural and psychological processes in pregnancy may be important antecedents for caregiving postpartum. Employing event-related potentials, we examined neural reactivity to infant emotional faces during the third trimester of pregnancy in expectant mothers (n = 38) and expectant fathers (n = 30). Specifically, expectant parents viewed infant distress and infant neutral faces while electroencephalography was simultaneously recorded. As a psychological measure, we assessed prenatal mind-mindedness towards the unborn child and examined whether neural processing of infant cues was associated with levels of mind-mindedness. Expectant fathers evidenced greater P300 reactivity to infant distress, relative to neutral, faces than expectant mothers. Furthermore, P300 reactivity to infant distress, relative to infant neutral, faces was associated with levels of prenatal mind-mindedness in expectant fathers but not expectant mothers. These findings indicate significant sex differences in the prenatal neural processing of infant cues and relations between neural reactivity to infant distress and the emergence of parental mind-mindedness.

Prior reproductive experience modulates neural responses to infant faces across the postpartum period

Infant-cue processing facilitates sensitive maternal care, which is necessary in the formation of healthy mother-infant attachment. Mothers may be particularly focused on cue processing early postpartum, contributing to intense preoccupation with their infant's well-being. Prior reproductive experience, or parity, may also impact the intensity of infant-cue processing and has been found to influence P300 neural responses to infant faces during pregnancy and at 2 months postpartum. However, we do not know whether this parity effect persists. Thus, we examined the P300 to infant faces in 59 mothers at 2 and 7 months postpartum. Our main finding was that primiparous, as compared to multiparous, women showed a significantly higher P300 to infant faces across the postpartum period. Findings further emphasize the importance of studying parity and its impact on the neural processing of infant faces.

Does anxiety impact the neural processing of child faces in mothers of school-aged children? An ERP study using an emotional Go/NoGo task

Maternal anxiety during pregnancy and the early postpartum period is associated with heightened neural processing of neutral infant faces as measured by event-related potentials (ERPs). However, less is known about how anxiety shapes neural face processing in mothers of older children. In our study, 36 mothers of 8-10 year old children completed a Go/NoGo task consisting of neutral and emotional (happy, fearful) facial expressions posed by unfamiliar school-aged children while EEG was recorded. Higher levels of maternal anxiety -indexed via self-report- were associated with delayed behavioral responses to children's fearful faces and increased N170 and LPP amplitudes elicited by children's neutral faces. While anxiety was also positively related to the LPP elicited by children's emotional faces, it only led to increased N170 amplitude responses to children's fearful, but not happy, faces and only when they were NoGo cues. The study replicates and extends prior findings examining the impact of maternal anxiety on neural responses to neutral infant faces to later stages of parenting with further neural markers and emotional expressions being affected. Findings evidence the importance of studying these associations beyond infancy to increase our knowledge about processes potentially underlying the relation between anxiety and less optimal parenting across development.

Attention bias to infant faces in pregnant women predicts maternal sensitivity

While research has shown that attention bias to infant faces is linked to parenting, this work is largely cross-sectional and limited to the postpartum period. Because the transition to motherhood from pregnancy to birth constitutes a sensitive period in cortical reorganization linked to the quality of mother-infant interactions, evaluating attention processes in the maternal cortex prior to the experience of mother-infant face-to-face interactions is critical. To assess behavioural attention and neural responses to infant faces in pregnant mothers, behavioral and electrocortical indices were collected using a Go/No Go task, in which infant and adult faces served as distractors. Results showed that heightened processing of infant faces relative to adult faces (behavioral and electrocortical indices) was related to observations of greater maternal sensitivity. These findings show that prenatal maternal attention bias to and the perceived salience of infant faces serves as an individual cognitive hallmark of maternal sensitivity that acts independently of caregiving experience.

Inaudible components of the human infant cry influence haemodynamic responses in the breast region of mothers

Distress vocalizations are fundamental for survival, and both sonic and ultrasonic components of such vocalizations are preserved phylogenetically among many mammals. On this basis, we hypothesized that ultrasonic inaudible components of the acoustic signal might play a heretofore hidden role in humans as well. By investigating the human distress vocalization (infant cry), here we show that, similar to other species, the human infant cry contains ultrasonic components that modulate haemodynamic responses in mothers, without the mother being consciously aware of those modulations. In two studies, we measured the haemodynamic activity in the breasts of mothers while they were exposed to the ultrasonic components of infant cries. Although mothers were not aware of ultrasounds, the presence of the ultrasounds in combination with the audible components increased oxygenated haemoglobin concentration in the mothers' breast region. This modulation was observed only when the body surface was exposed to the ultrasonic components. These findings provide the first evidence indicating that the ultrasonic components of the acoustic signal play a role in human mother-infant interaction.

Mothers' neural responses to infant faces are associated with activation of the maternal care system and observed intrusiveness with their own child

Certain infant facial characteristics, referred to as baby schema, are thought to automatically trigger parenting behavior and affective orientation toward infants. Electroencephalography (EEG) is well suited to assessing the intuitive nature and temporal dynamics of parenting responses, due to its millisecond temporal resolution. Little is known, however, about the relations between neural processing of infant cues and actual parenting behavior in a naturalistic setting. In the present study we examined the event-related potentials (ERPs) of mothers (N = 33) watching infant faces of varying attractiveness, in relation to activation of the maternal care system and the mothers’ observed parenting behavior (sensitivity, nonintrusiveness) with their own child (2–6 years old). The results revealed that, irrespective of the cuteness of the infant face, mothers’ neural processing of infant faces involved both early P1 and P2 components (related to orienting/detecting processes) and late positive potentials (LPPs; related to more controlled cognitive evaluation/attentional engagement). Increased early detection and processing of infant faces (reflected by P1 and P2 activity) was related to increased activation of the parental care system. In later stages of face processing, increased attentional engagement with infant faces (as reflected by LPP activity) was associated with more intrusiveness of a mother with her own child during interaction. These findings suggest that individual variations in responses to infant stimuli are associated with individual differences in parental care system activation and parenting quality. Furthermore, the parental care system might be activated relatively automatically, but actual parenting and caregiving behavior requires more conscious control.

Early processing (N170) of infant faces in mothers of children with autism spectrum disorder and its association with maternal sensitivity

Individuals with autism spectrum disorder (ASD) exhibit impaired adult facial processing, as shown by the N170 event-related potential. However, few studies explore such processing in mothers of children with ASD, and none has assessed the early processing of infant faces in these women. Moreover, whether processing of infant facial expressions in mothers of children with ASD is related to their response to their child's needs (maternal sensitivity [MS]) remains unknown. This study explored the N170 related to infant faces in a group of mothers of children with ASD (MA) and a reference group of mothers of children without ASD. For both emotional (crying, smiling) and neutral expressions, the MA group exhibited larger amplitudes of N170 in the right hemisphere, while the reference group showed similar interhemispheric amplitudes. This lateralization effect within the MA group was not present for nonfaces and was stronger in the mothers with higher MS. We propose that mothers of ASD children use specialized perceptual resources to process infant faces, and this specialization is mediated by MS. Our findings suggest that having an ASD child modulates mothers' early neurophysiological responsiveness to infant cues. Whether this modulation represents a biological marker or a response given by experience remains to be explored. Autism Research 2019, 12: 744-758. © 2019 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: When mothers of children with autism spectrum disorder (ASD) see baby faces expressing emotions, they show a right-sided electrical response in the brain. This lateralization was stronger in mothers who were more sensitive to their children's needs. We conclude that having a child with ASD and being more attuned to their behavior generates a specialized pattern of brain activity when processing infant faces. Whether this pattern is biological or given by experience remains to be explored.

Latent profiles of maternal neural response to infant emotional stimuli: Associations with maternal sensitivity

In the current study, we examined how latent profiles reflecting maternal neural response to infant emotional expressions predict observed parenting behavior. Participants included 86 mothers of infants. Maternal sensitivity was coded from video-recorded distress and play interactions; mothers' event-related potentials (ERPs) to child emotional expressions were measured from EEG activity recorded during a categorization task. Latent profile analysis of mothers' P200 and late positive potential (LPP) responses to crying and laughing child expressions identified three latent profiles, characterized by enhanced or attenuated responses to crying and laughing expressions at early and late stages of processing. Mothers' probability of being assigned to the "attenuated to distress" profile, characterized by undifferentiated early and late response to infant emotional expressions, was associated with reduced maternal sensitivity. Probability of being assigned to this profile was also correlated with sociodemographic risk. Profiles of maternal neural response to infant emotional expressions may enhance our understanding of the phenomenology of insensitive caregiving.

Changes in Cortical Sensitivity to Infant Facial Cues From Pregnancy to Motherhood Predict Mother-Infant Bonding

The transition to motherhood triggers changes in human brain structure that may facilitate mother-infant bonding. Although much research on maternal cortical responses to infant faces has focused on the postpartum period, no previous study has examined whether longitudinal functional changes in the maternal cortex during pregnancy and postpartum are associated with mother-infant bonding. Using electroencephalography, prenatal to postnatal changes in cortical sensitivity (P1, P2, late positive potential, N170 event-related potentials) to infant and adult faces were examined in relation to reported mother-infant bonding in 40 mothers (M_age  = 30.5 years). Prenatal to postnatal increases in P1 and P2 responses to infant faces predicted stronger bonding. Findings suggest that cortical changes in attention allocation rather than in face-specific encoding enhance bonding.

Differential Effects of Intranasal Vasopressin on the Processing of Adult and Infant Cues: An ERP Study

Arginine vasopressin (AVP) is a powerful regulator of various social behaviors across many species. However, seemingly contradictory effects of AVP have been found in both animal and human studies, e.g., promoting aggression on one hand and facilitating social bonding on the other hand. Therefore, we hypothesize that the role of AVP in social behaviors is context-dependent. To this end, we examined the modulatory effect of AVP on male’s behavioral and neural responses to infant and adult cues. After intranasal and double-blind treatment of AVP or placebo, male participants were asked to rate their subjective approaching willingness to infant and adult faces in specific contexts informed by cue words while EEG recording. Our results showed that AVP treatment increased approaching ratings to neutral and positive other-gender adult faces compared to emotional matched same-gender adult faces, and to negative girl faces compared to negative boy faces. Furthermore, compared to placebo treatment, AVP treatment induced larger N1 amplitudes to neutral cues associated with both adults and infants, whereas AVP treatment only sustained pronounced late positive potential amplitudes to neutral cues of infants but not adults. Those findings implicate differential roles of AVP in the processing of adult- and infant-related cues and thus lend support to the context-dependent account.

Maternal report of infant negative affect predicts attenuated brain response to own infant

Parent-infant interaction is known to be influenced bidirectionally by parent and infant characteristics. However, it is unclear whether infant temperament affects parents' neural responses to infant stimuli. 85 infants (6-12 months) were filmed in distress-eliciting tasks, which were coded for infants' negative affect. Mothers' reported infant affect was obtained from the Infant Behavior Questionnaire Very Short Form-Revised. Mothers' EEG activity was recorded while passively viewing photos of own, familiarized, and unfamiliar infants. Multiple regression indicated that mothers who reported greater infant negative affect showed a smaller difference in the late positive potential (LPP) response to own infant versus familiarized infant, controlling for researcher-coded infant negative affect. The findings suggest that parents' perceptions of their infant's temperament, but not independent measures of infant temperament, are related to electrocortical indices of emotional attention.

The special status of sad infant faces: age and valence differences in adults' cortical face processing

Understanding the relative and joint prioritization of age- and valence-related face characteristics in adults’ cortical face processing remains elusive because these two characteristics have not been manipulated in a single study of neural face processing. We used electroencephalography to investigate adults’ P1, N170, P2 and LPP responses to infant and adult faces with happy and sad facial expressions. Viewing infant vs adult faces was associated with significantly larger P1, N170, P2 and LPP responses, with hemisphere and/or participant gender moderating this effect in select cases. Sad faces were associated with significantly larger N170 responses than happy faces. Sad infant faces were associated with significantly larger N170 responses in the right hemisphere than all other combinations of face age and face valence characteristics. We discuss the relative and joint neural prioritization of infant face characteristics and negative facial affect, and their biological value as distinct caregiving and social cues.

Attention allocation towards own face is pronounced during middle adolescence: an eye-tracking study

Increased interest in the self has long been deemed to be one of the most peculiar characteristics of adolescence. On the basis of this, we conjectured that attentiveness towards self-relevant information, especially one's own face, becomes more pronounced during the middle adolescence. The present study tested this hypothesis by comparing the pattern of visuospatial attention allocation to their own face among early, middle and late adolescent males using an eye-tracking methodology. The results have shown a clear pattern of increased attention allocation towards their own face over a close friend's and a stranger's face in middle adolescents, but fixation durations on their own and a friend's face did not differ from each other in early and late adolescents. In addition, middle adolescents showed higher public self-consciousness and a lower level of self-esteem than early and late adolescents, respectively. These results indicate that attention allocation towards one's own face is more pronounced during middle adolescence, and is associated with increased interest in their own attributes.

Maternal Attachment Representation and Neurophysiological Processing during the Perception of Infants' Emotional Expressions

The perception of infant emotions is an integral part of sensitive caregiving within the mother-child relationship, a maternal ability which develops in mothers during their own attachment history. In this study we address the association between maternal attachment representation and brain activity underlying the perception of infant emotions. Event related potentials (ERPs) of 32 primiparous mothers were assessed during a three stimulus oddball task presenting negative, positive and neutral emotion expressions of infants as target, deviant or standard stimuli. Attachment representation was assessed with the Adult Attachment Interview during pregnancy. Securely attached mothers recognized emotions of infants more accurately than insecurely attached mothers. ERPs yielded amplified N170 amplitudes for insecure mothers when focusing on negative infant emotions. Secure mothers showed enlarged P3 amplitudes to target emotion expressions of infants compared to insecure mothers, especially within conditions with frequent negative infant emotions. In these conditions, P3 latencies were prolonged in insecure mothers. In summary, maternal attachment representation was found associated with brain activity during the perception of infant emotions. This further clarifies psychological mechanisms contributing to maternal sensitivity.

Attachment representation modulates oxytocin effects on the processing of own-child faces in fathers

Oxytocin (OT) plays a crucial role in parental-infant bonding and attachment. Recent functional imaging studies reveal specific attachment and reward related brain regions in individuals or within the parent-child dyad. However, the time course and functional stage of modulatory effects of OT on attachment-related processing, especially in fathers, are poorly understood. To elucidate the functional and neural mechanisms underlying the role of OT in paternal-child attachment, we performed an event-related potential study in 24 healthy fathers who received intranasal OT in a double-blind, placebo-controlled, within-subject experimental design. Participants passively viewed pictures of their own child (oC), a familiar (fC) and an unfamiliar child (ufC) while event-related potentials were recorded. Familiarity of the child's face modulated a broad negativity at occipital and temporo-parietal electrodes within a time window of 300-400ms, presumably reflecting a modulation of the N250 and N300 ERP components. The oC condition elicited a more negative potential compared to the other familiarity conditions suggesting different activation of perceptual memory representations and assignment of emotional valence. Most importantly, this familiarity effect was only observed under placebo (PL) and was abolished under OT, in particular at left temporo-parietal electrodes. This OT induced attenuation of ERP responses was related to habitual attachment representations in fathers. In summary, our results demonstrate an OT-specific effect at later stages of attachment-related face processing presumably reflecting both activation of perceptual memory representations and assignment of emotional value.

Parental brain: cerebral areas activated by infant cries and faces. A comparison between different populations of parents and not

Literature about parenting traditionally focused on caring behaviors and parental representations. Nowadays, an innovative line of research, interested in evaluating the neural areas and hormones implicated in the nurturing and caregiving responses, has developed. The only way to permit a newborn to survive and grow up is to respond to his needs and in order to succeed it is necessary, first of all, that the adults around him understand what his needs are. That is why adults' capacity of taking care of infants cannot disregard from some biological mechanisms, which allow them to be more responsive to the progeny and to infants in general. Many researches have proved that exist specific neural basis activating in response to infant evolutionary stimuli, such as infant cries and infant emotional facial expression. There is a sort of innate predisposition in human adults to respond to infants' signals, in order to satisfy their need and allow them to survive and become young adults capable of taking care of themselves. This article focuses on research that has investigated, in the last decade, the neural circuits underlying parental behavioral responses. Moreover, the paper compares the results of those studies that investigated the neural responses to infant stimuli under different conditions: familiar versus unknown children, parents versus non-parents and normative versus clinical samples (depression, addiction, adolescence, and PTSD).

Maternal anxiety and neural responses to infant faces

BACKGROUND

Women may be especially vulnerable to anxiety during the postpartum period and early infancy. However, little is known regarding the potential impact of maternal anxiety on the neural processing of infant-relevant information.

METHODS

In this ERP study, 47 recent mothers viewed neutral and distressed infant faces, concurrent with EEG collection. We examined the N170 as a perceptual marker of face processing and the late positive potential (LPP) as an index of engagement with stimulus processing. Mothers also completed the Spielberger State-Trait Anxiety Inventory.

RESULTS

While the N170 was unaffected by infant affect and anxiety levels, the LPP was greater in amplitude for distressed vs. neutral faces. Moreover, the degree of LPP amplitude elicited by neutral infant faces was positively correlated with state anxiety. There were no associations between anxiety and the LPP elicited by distressed infant faces.

LIMITATIONS

We employed self-report measures of state and trait anxiety symptomatology and including diagnostic classification of anxiety disorders will be important in future research.

CONCLUSIONS

These results indicate that recent mothers with higher levels of state anxiety may be more engaged with processing neutral infant cues.

Neurofunctional maps of the 'maternal brain' and the effects of oxytocin: a multimodal voxel-based meta-analysis

Several studies have tried to understand the possible neurobiological basis of mothering. The putative involvement of oxytocin, in this regard, has been deeply investigated. Performing a voxel-based meta-analysis, we aimed at testing the hypothesis of overlapping brain activation in functional magnetic resonance imaging (fMRI) studies investigating the mother-infant interaction and the oxytocin modulation of emotional stimuli in humans. We performed two systematic literature searches: fMRI studies investigating the neurofunctional correlates of the 'maternal brain' by employing mother-infant paradigms; and fMRI studies employing oxytocin during emotional tasks. A unimodal voxel-based meta-analysis was performed on each database, whereas a multimodal voxel-based meta-analytical tool was adopted to assess the hypothesis that the neurofunctional effects of oxytocin are detected in brain areas implicated in the 'maternal brain.' We found greater activation in the bilateral insula extending to the inferior frontal gyrus, basal ganglia and thalamus during mother-infant interaction and greater left insular activation associated with oxytocin administration versus placebo. Left insula extending to basal ganglia and frontotemporal gyri as well as bilateral thalamus and amygdala showed consistent activation across the two paradigms. Right insula also showed activation across the two paradigms, and dorsomedial frontal cortex activation in mothers but deactivation with oxytocin. Significant activation in areas involved in empathy, emotion regulation, motivation, social cognition and theory of mind emerged from our multimodal meta-analysis, supporting the need for further studies directly investigating the neurobiology of oxytocin in the mother-infant relationship.

Immediate and selective maternal brain responses to own infant faces

Infant faces elicit caregiving in adults. In previous research on brain responses to images of infant faces, the faces were unknown to participants. This study investigated EEG in primiparous mothers of 3- to 6-month-old infants viewing their own infant's face compared to an unfamiliar but appearance-matched infant's face. Spectral power was calculated and compared, and power at three EEG bands (delta, theta, and gamma) was found to differ between faces. Brain responses among primiparous mothers distinguish images of their own versus unfamiliar infants.

Prospective and retrospective semantic processing: prediction, time, and relationship strength in event-related potentials

Semantic context effects have variously been attributed to prospective processing - predictions about upcoming words - or to retrospective appreciation of relationships after reading both context and target. In two experiments, we altered the core variable distinguishing prospective from retrospective processing, namely time. Word pairs varying in strength of relationship were presented sequentially, to allow time for anticipation of the second word, or simultaneously. For both sorts of presentation, the amplitude of the N400 component of the event-related potential was graded from Unrelated to Moderate/Weak to Strong associates. Strong associates showed a temporal advantage over weaker associates - an earlier context effect - only during sequential presentation. Spatial distributions of the N400 context effects also differed for simultaneous versus sequential presentation.

Differentiated brain activity in response to faces of "own" versus "unfamiliar" babies in primipara mothers: an electrophysiological study

Experiences with one's own infant attune the parent nervous system to infant stimuli. To explore the effects of motherhood on brain activity patterns, electroencephalogram (EEG) was recorded while primipara mothers of 3- and 6-month-olds viewed images of faces of their own child and an unfamiliar but appearance-matched child. Mothers of 3- and 6-month-olds showed equivalent early-wave (N/P1 "visual" and N170 "face-sensitive") responses to own and unfamiliar baby faces but differentiating late-wave (N/P600 "familiar/ novel") activity to own versus unfamiliar infant faces. Based on 3 months experience with their own infant's face, mothers' brain patterns give evidence of distinctive late-wave (recognition) sensitivity.

Is attentional prioritisation of infant faces unique in humans?: Comparative demonstrations by modified dot-probe task in monkeys

Humans innately perceive infantile features as cute. The ethologist Konrad Lorenz proposed that the infantile features of mammals and birds, known as the baby schema (kindchenschema), motivate caretaking behaviour. As biologically relevant stimuli, newborns are likely to be processed specially in terms of visual attention, perception, and cognition. Recent demonstrations on human participants have shown visual attentional prioritisation to newborn faces (i.e., newborn faces capture visual attention). Although characteristics equivalent to those found in the faces of human infants are found in nonhuman primates, attentional capture by newborn faces has not been tested in nonhuman primates. We examined whether conspecific newborn faces captured the visual attention of two Japanese monkeys using a target-detection task based on dot-probe tasks commonly used in human visual attention studies. Although visual cues enhanced target detection in subject monkeys, our results, unlike those for humans, showed no evidence of an attentional prioritisation for newborn faces by monkeys. Our demonstrations showed the validity of dot-probe task for visual attention studies in monkeys and propose a novel approach to bridge the gap between human and nonhuman primate social cognition research. This suggests that attentional capture by newborn faces is not common to macaques, but it is unclear if nursing experiences influence their perception and recognition of infantile appraisal stimuli. We need additional comparative studies to reveal the evolutionary origins of baby-schema perception and recognition.