Neural representations of the body in 60‐day‐old human infants

The organization of body representations in the adult brain has been well documented. Little is understood about this aspect of brain organization in human infancy. The current study employed electroencephalography (EEG) with 60‐day‐old infants to test the distribution of brain responses to tactile stimulation of three different body parts: hand, foot, and lip. Analyses focused on a prominent positive response occurring at 150–200 ms in the somatosensory evoked potential at central and parietal electrode sites. The results show differential electrophysiological signatures for touch of these three body parts. Stimulation of the left hand was associated with greater positive amplitude over the lateral central region contralateral to the side stimulated. Left foot stimulation was associated with greater positivity over the midline parietal site. Stimulation of the midline of the upper lip was associated with a strong bilateral response over the central region. These findings provide new insights into the neural representation of the body in infancy and shed light on research and theories about the involvement of somatosensory cortex in infant imitation and social perception.     

Social touch alters newborn monkey behavior

In humans, infants respond positively to slow, gentle stroking—processed by C-tactile (CT) nerve fibers—by showing reductions in stress and increases in eye contact, smiling, and positive vocalizations. More frequent maternal touch is linked to greater activity and connectivity strength in social brain regions, and increases children’s attention to and learning of faces. It has been theorized that touch may prime children for social interactions and set them on a path towards healthy social cognitive development. However, less is known about the effects of touch on young infants’ psychological development, especially in the newborn period, a highly sensitive period of transition with rapid growth in sensory and social processing. It remains untested whether newborns can distinguish CT-targeted touch from other types of touch, or whether there are benefits of touch for newborns’ social, emotional, or cognitive development. In the present study, we experimentally investigated the acute effects of touch in newborn monkeys, a common model for human social development. Rhesus macaques (Macaca mulatta), like humans, are highly social, have complex mother-infant interactions with frequent body contact for the first weeks of life, making them an excellent model of infant sociality. Infant monkeys in the present study were reared in a neonatal nursery, enabling control over their early environment, including all caregiver interactions. One-week-old macaque infants (N = 27) participated in three 5-minute counter-balanced caregiver interactions, all with mutual gaze: stroking head and shoulders (CT-targeted touch), stroking palms of hands and soles of feet (Non-CT touch), or no stroking (No-touch). Immediately following the interaction, infants watched social and nonsocial videos and picture arrays including faces and objects, while we tracked their visual attention with remote eye tracking. We found that, during the caregiver interactions, infants behaved differently while being touched compared to the no-touch condition, irrespective of the body part touched. Most notably, in both touch conditions, infants exhibited fewer stress-related behaviors—self-scratching, locomotion, and contact time with a comfort object—compared to when they were not touched. Following CT-targeted touch, infants were faster to orient to the picture arrays compared to the other interaction conditions, suggesting CT-targeted touch may activate or prime infants’ attentional orienting system. In the No-touch condition infants attended longer to the nonsocial compared to the social video, possibly reflecting a baseline preference for nonsocial stimuli. In contrast, in both touch conditions, infants’ looked equally to the social and nonsocial videos, suggesting that touch may influence the types of visual stimuli that hold infants’ attention. Collectively, our results reveal that newborn macaques responded positively to touch, and touch appeared to influence some aspects of their subsequent attention, although we found limited evidence that these effects are mediated by CT fibers. These findings suggest that newborn touch may broadly support infants’ psychological development, and may have early evolutionary roots, shared across primates. This study illustrates the unique insight offered by nonhuman primates for exploring early infant social touch, revealing that touch may positively affect emotional and attentional development as early as the newborn period.     

The rubber hand illusion depends on a congruent mapping between real and artificial fingers

The rubber hand illusion (RHI), in which a visible artificial hand is touched (or moves) synchronously with the participant's unseen own hand, indicates that body representations can undergo rapid changes. While several constraints for this illusion have been described, some reports highlight a remarkable flexibility of body representations, even contradicting a priori assumptions regarding body appearance and anatomy (e.g., the subjective embodiment of a third arm).     

Touchant-touché: the role of self-touch in the representation of body structure

The "body image" is a putative mental representation of one's own body, including structural and geometric details, as well as the more familiar visual and affective aspects. Very little research has investigated how we learn the structure of our own body, with most researchers emphasising the canonical visual representation of the body when we look at ourselves in a mirror. Here, we used non-visual self-touch in healthy participants to investigate the possibility that primary sensorimotor experience may influence cognitive representations of one's own body structure. Participants used the fingers of one hand (the 'active' hand), to touch the fingers of the other (the 'passive' hand). A conflict between the experience of the active and passive hand was introduced by experimenter interleaving their fingers with the fingers of the participant's passive hand. This led to the active hand experiencing that it touched more fingers than the passive hand felt it was being touched by. The effects on representation of body structure were assessed using an implicit measure based on Kinsbourne and Warrington's 'in-between task'. We found an underestimation of the number of fingers in the central part of the hand specifically linked to the experience of self-touch. This pattern of results corresponds to the experience of the passive hand, but not the active hand. Nevertheless, comparable reorganisation of fingers within the hand representation was found for both active and passive hands. We show that primary sensorimotor experience can modify the representation of body structure. This modification is driven by the passive experience of being touched, rather than by the active experience of touching. We believe this is the first experimental study of effects of self-touch on the mental representation of the body.     

Viewing a face (especially one's own face) being touched enhances tactile perception on the face

Observing touch on another person's body activates brain regions involved in tactile perception, even when the observer's body is not directly stimulated. Previous work has shown that in some synaesthetes, this effect induces a sensation of being touched. The present study shows that if perceptual thresholds are experimentally manipulated, viewing touch can modulate tactile experience in nonsynaesthetes as well. When observers saw a face being touched by hands, rather than a face being merely approached by hands, they demonstrated enhanced detection of subthreshold tactile stimuli on their own faces. This effect was specific to observing touch on a body part, and was not found for touch on a nonbodily stimulus, namely, a picture of a house. In addition, the effect was stronger when subjects viewed their own faces rather than another person's face. Thus, observing touch can activate the tactile system, and if perceptual thresholds are manipulated, such activation can result in a behavioral effect in nonsynaesthetes. The effect is maximum if the observed body matches the observer's body.     

Maternal representations and emotional availability among drug‐abusing and nonusing mothers and their infants

Both negative and idealized maternal prenatal representations may constitute a risk for mother–infant interaction. This study analyzed the role of maternal prenatal representations and pre‐ to postnatal representational change in predicting mother–infant emotional availability (EA) among 51 drug‐abusing mothers and their infants who participated in either psychodynamic group therapy (PGT) or received psychosocial support (PSS) and among 50 nonusing comparison dyads. Maternal representations of her child, the child's father, her own mother, self‐as‐mother, and self‐as‐woman were measured during pregnancy and at 4 and 12 months' postpartum with the Interview of Maternal Representations (M. Ammaniti et al., 1992 ; M. Ammaniti, R. Tambelli, & P. Perucchini, 1998). EA was measured with the Emotional Availability Scales, fourth edition (Z. Biringen, 2008 ) at 4 and 12 months. The results showed that drug‐abusing mothers had more negative prenatal representations of the self‐as‐woman and of the child's father. Postnatally, PSS mothers tended to first idealize their child, but later to experience disillusionment of idealization. Both negative and idealized prenatal representations of the self‐as‐mother predicted mother–infant EA problems, but only among the PGT mothers. For all mothers, negative representational change was detrimental for the mother–infant EA whereas for drug‐abusing mothers, also increasing idealization from the prenatal period to the postnatal period was harmful. Clinicians working with drug‐abusing mothers should aim at supporting the development of a realistically positive view of motherhood.     

The effect of relational stage and intimacy on touch: An extension of Guerrero and Andersen

The effects of relational stage, intimacy, and gender on touch were examined. Participants were 270 partners from 135 couples involved in a heterosexual romantic relationship. Results indicated that touch varies as a function of relational stage. An examination of relational stage and subjects' perceptions of how much they touched their partner and how much their partner touched them generally indicated an asymptotic relationship. Specifically, men's and women's perceptions of how much they touched their partners, and women's perceptions of how much their partners touched them, increased from the casually dating to the seriously dating stage and then leveled off for seriously dating, engaged, and married couples. Men's perceptions of how much their partners touched them increased from the casually dating to the seriously dating stage then decreased from the seriously dating to the married stage. Relational intimacy was also curvilinearly related to self and partner perceptions of touch. Because there were no significant interaction effects between stage and gender, or intimacy and gender, the curvilinear effects of relational stage and intimacy on touch are generalizable to both men and women.     

Mental body representations retain homuncular shape distortions: Evidence from Weber’s illusion

Mental body representations underlying tactile perception do not accurately reflect the body’s true morphology. For example, perceived tactile distance is dependent on both the body part being touched and the stimulus orientation, a phenomenon called Weber’s illusion. These findings suggest the presence of size and shape distortions, respectively. However, whereas each morphological feature is typically measured in isolation, a complete morphological characterization requires the concurrent measurement of both size and shape. We did so in three experiments, manipulating both the stimulated body parts (hand; forearm) and stimulus orientation while requiring participants to make tactile distance judgments. We found that the forearm was significantly more distorted than the hand lengthwise but not widthwise. Effects of stimulus orientation are thought to reflect receptive field anisotropies in primary somatosensory cortex. The results of the present study therefore suggest that mental body representations retain homuncular shape distortions that characterize early stages of somatosensory processing.     

Maternal perceptions of the infant: Relationship to maternal self‐efficacy during the first six weeks' postpartum

Mothers' perceptions of their infants and their own levels of self‐efficacy contribute to developing maternal‐infant attunement. The purpose of this investigation was to examine the associations between maternal perceptions of their own infants relative to other infants and maternal self‐efficacy in a group of ethnically diverse, low‐income, first‐time mothers during the first six weeks postpartum. By employing a structural equation model approach, we explored relationships between the predictor (maternal neonatal perceptions) and dependent variable (maternal self‐efficacy). Changes in maternal perceptions of their own infants significantly contributed to self‐reported levels of self‐efficacy while controlling for concurrent self‐esteem. Maternal perceptions of her infant as less difficult than the average infant at six weeks postpartum predicted increased levels of maternal self‐reported self‐efficacy. The present study supports further exploration of the first six weeks postpartum as a sensitive period for targeting intervention and support, particularly for mothers and infants at highest risk.     

Visual enhancement of touch and the bodily self

We experience our own body through both touch and vision. We further see that others’ bodies are similar to our own body, but we have no direct experience of touch on others’ bodies. Therefore, relations between vision and touch are important for the sense of self and for mental representation of one’s own body. For example, seeing the hand improves tactile acuity on the hand, compared to seeing a non-hand object. While several studies have demonstrated this visual enhancement of touch (VET) effect, its relation to the ‘bodily self’, or mental representation of one’s own body remains unclear. We examined whether VET is an effect of seeing a hand, or of seeing my hand, using the rubber hand illusion. In this illusion, a prosthetic hand which is brushed synchronously—but not asynchronously—with one’s own hand is felt to actually be one’s hand. Thus, we manipulated whether or not participants felt like they were looking directly at their hand, while holding the actual stimulus they viewed constant. Tactile acuity was measured by having participants judge the orientation of square-wave gratings. Two characteristic effects of VET were observed: (1) cross-modal enhancement from seeing the hand was inversely related to overall tactile acuity, and (2) participants near sensory threshold showed significant improvement following synchronous stroking, compared to asynchronous stroking or no stroking at all. These results demonstrate a clear functional relation between the bodily self and basic tactile perception.     

Exploring maternal touch in the infant’s first 18 months of Life: A study on an Italian sample

Affective touch is a crucial component of caregiving in early life and constitutes a key factor with a significant impact on infant later-life outcomes. The Parent-Infant Caregiving Touch Scale (PICTS) allows to quantify and qualify the caregiver's self-perception of touch in the first months of an infant’s life. In the current study, we contributed to validation of the PICTS in the Italian language in order to explore whether early maternal touch would be associated with maternal emotional state, maternal history of affective touch experiences throughout the lifespan, and infants’ sex and age. Data analyses were run on a sample of 377 Italian mothers (mean age = 33.29; SD = 4.79) participating in an online survey. Confirmatory factor analysis was applied. A three-dimensional structure of PICTS (i.e., stroking, affective communication, and holding) after removing one item out resulted in the best model in our sample. Maternal emotional state did not affect PICTS factor scores while maternal comfort and amount of affective touch experienced during adulthood was significantly associated with the stroking, affective communication, and holding factors. Regarding infants’ dimensions, infants’ sex and age were not associated with PICTS factor scores. Findings suggest that the PICTS Italian version is a good measurement of caregiver's self-perception of touch in early infancy and that maternal history of touch is associated with a mother’s current use of touch.     

Face-to-face interaction behavior across early infancy

Stability and change in mother-infant interaction behavior were assessed across early infancy. At 8 versus 4 months, the infants showed more smiling, vocalizing and motor-activity, and their mothers touched and moved their infants' limbs less often. Stability was noted only for infant distress-brow and mother's touching the infant. Although very few relationships were apparent between mother and infant behavior at 4 months, several maternal behaviors at 4 months were related to infant behaviors at 8 months, and several relationships were noted between maternal and infant behavior at 8 months.     

Active and passive-touch during interpersonal multisensory stimulation change self–other boundaries

In the “enfacement” illusion seeing an unfamiliar face being touched at the same time as one’s own face evokes changes in self-face recognition. We investigated the contribution of proprioceptive and motor signals derived from self-generated actions in the sensory-driven malleability of self–other boundaries during the “enfacement” illusion. Changes in self-face recognition during active- and passive-touch interpersonal visuo-tactile stimulation were quantified by means of psychophysical and psychometric tasks. Active- and passive-touch evoked comparable changes in the categorical boundaries of self–other distinction, changing the extent to which the other is assimilated into the mental self-representation. Actively touching or simply feeling touch on one’s own face with concurrent observed touch on someone else’s face seems to elicit comparable changes in self-recognition, suggesting that afferent input might be sufficient for updating one’s body-image, although some components of the experience of self-identification seem to be more affected by passive- than by active-touch.     

Recognizing familiar objects by hand and foot: Haptic shape perception generalizes to inputs from unusual locations and untrained body parts

The limits of generalization of our 3-D shape recognition system to identifying objects by touch was investigated by testing exploration at unusual locations and using untrained effectors. In Experiments 1 and 2, people found identification by hand of real objects, plastic 3-D models of objects, and raised line drawings placed in front of themselves no easier than when exploration was behind their back. Experiment 3 compared one-handed, two-handed, one-footed, and two-footed haptic object recognition of familiar objects. Recognition by foot was slower (7 vs. 13 s) and much less accurate (9 % vs. 47 % errors) than recognition by either one or both hands. Nevertheless, item difficulty was similar across hand and foot exploration, and there was a strong correlation between an individual’s hand and foot performance. Furthermore, foot recognition was better with the largest 20 of the 80 items (32 % errors), suggesting that physical limitations hampered exploration by foot. Thus, object recognition by hand generalized efficiently across the spatial location of stimuli, while object recognition by foot seemed surprisingly good given that no prior training was provided. Active touch (haptics) thus efficiently extracts 3-D shape information and accesses stored representations of familiar objects from novel modes of input.     

Infant touching behaviour during mother–infant face‐to‐face interactions

The study of infant communication during mother–infant interactions has largely focused on infants' distal behaviours, while neglecting their more proximal behaviours, such as touch. Yet, touch is an important modality through which infants and mothers communicate; it is also a vital means through which infants self‐regulate and explore their surroundings. The present study was designed to investigate the touching behaviours of 44, 51/2‐month‐old, healthy, full‐term infants during face‐to‐face mother–infant interactions. A still‐face (SF) procedure was used in order to examine differences in the types and locations of infant touch across normal and perturbed interaction periods, when mothers exhibit changes in their emotional availability. Results revealed that infant touch varied with changes in maternal availability. During the SF period, when mothers were unavailable, infants used more active, soothing, and reactive tactile behaviours (stroke, finger, pat, and pull), and they spent more time touching themselves. In contrast, infants used mostly passive touch (static) during the Normal periods, when their mothers were available. They also spent a significant portion of time touching their mothers. The variations in infant touch across periods suggest that infants communicate their affective states through touch. The findings also support the regulatory and exploratory roles of infant touch, especially during periods of maternal unavailability. Copyright © 2007 John Wiley & Sons, Ltd.     

Mother's attachment representations of their premature infant at 6 and 18 months after birth

The effects of premature birth on attachment have generally been examined from the infant's perspective. There is a lack of data concerning parental attachment representations toward a premature child. Because of the psychological stress engendered in parents confronted with a premature birth, we hypothesized that their attachment representations would be altered during the first months after the hospital discharge. Fifty families with a premature infant (25–33 gestation weeks) and a control group of 30 families with a full‐term infant participated to the study. Perinatal risks were evaluated during hospitalization. To assess mothers' representations of their infant, the Working Model of the Child Interview (WMCI, Zeanah & Benoit, 1995 & Benoit, Zeanah, Parker, Nicholson, & Coolbear, 1997) were administered when their children were 6 and 18 months old. The severity of the perinatal risks was found to have an impact on the mothers' attachment representations. At six months, only 20% of the mothers of a prematurely born infant (30% at 18 months) had secure attachment representations, vs. 53% for the control group (57% at 18 months). Furthermore, mothers of low‐risk premature infants more often had disengaged representations, whereas distorted representations were more frequent in the high‐risk group of premature children. These findings suggest that the parental response to a premature birth is linked to the severity of postnatal risks. The fact that secure attachment representations are affected in mothers of low‐risk infants just as much as they are in mothers of high‐risk infants points to the need to conduct further studies aimed at evaluating whether preventive intervention for both low‐risk and high‐risk premature will be helpful.     

Early tactile experience of low birth weight children: links to later mental health and social adaptation

The purpose of this study was twofold: to determine (1) the degree to which specific qualities of maternal touch may contribute to the low birth weight infant's emotional and behavioural problems as well as social adaptation, and (2) the relationship between maternal touch and a mother's other caregiving behaviour. The sample included 114 socioculturally diverse infants and their mothers who were videotaped during an infant feeding when the baby was 3 months old. This videotape was analysed to assess dimensions of mother–infant interaction, including maternal touch. Data on perinatal risk and the mother's acceptance versus rejection of the infant were also acquired. Social adaptation and emotional/behavioural problems were measured when the child was 2 years of age. Hierarchical regression analyses indicated that maternal touch accounted for 15% of the variance in the likelihood of a child having emotional/behavioural problems at age 2. Children who received more nurturing touch had significantly fewer internalizing problems (such as depression) while children receiving both more frequent touch and harsh touch had more externalizing problems (such as aggressive behaviour). Infants who were less responsive to their caregivers were especially at risk of developing aggressive/destructive behaviour as a result of frequent touch. But less responsive infants also appeared to benefit most from greater use of diverse types of maternal touch, accounting for 6% of the variance in superior adaptive behaviour at age 2. Nurturing touch was the only quality that showed even a modest relationship to other caregiving behaviour, suggesting that touch may play a distinct role in the infant's psychosocial development. Copyright © 2001 John Wiley & Sons, Ltd.     

Experimental manipulation of infant temperament affects amygdala functional connectivity

In this functional magnetic resonance imaging (fMRI) study we examined neural processing of infant faces associated with a happy or a sad temperament in nulliparous women. We experimentally manipulated adult perception of infant temperament in a probabilistic learning task. In this task, participants learned about an infant's temperament through repeated pairing of the infant face with positive or negative facial expressions and vocalizations. At the end of the task, participants were able to differentiate between “mostly sad” infants who cried often and “mostly happy” infants who laughed often. Afterwards, brain responses to neutral faces of infants with a happy or a sad temperament were measured with fMRI and compared to brain responses to neutral infants with no temperament association. Our findings show that a brief experimental manipulation of temperament can change brain responses to infant signals. We found increased amygdala connectivity with frontal regions and the visual cortex, including the occipital fusiform gyrus, during the perception of infants with a happy temperament. In addition, amygdala connectivity was positively related to the post-manipulation ratings of infant temperament, indicating that amygdala connectivity is involved in the encoding of the rewarding value of an infant with a happy temperament.     

Mother–child and metapelet–child touch behavior with three‐year‐old kibbutz children in two contexts

The frequency and function of self‐touch and of touching another was studied among 32 three‐year‐old kibbutz children, their mothers, and their metaplot [caretakers; singular: metapelet] in two contexts: coconstruction of a narrative with Duplo toys, and coconstruction of a narrative with an emotion‐evoking picture book without text. Self‐touch, mainly fidgeting, was more frequent for children during the task with the picture book and more frequent for adults during the task with the Duplo toys. Mothers and children touched each other more often than metaplot and children. Adults' touches of the children were perceived as either expressions of affection or as acts of grooming and were task‐related. The children's touching of the adults was mainly task‐related. It appears that self‐touch is for children and adults alike a mode of self‐regulation of mild stress and that touching the other has a wide range of functions, especially in intimate relationships. ©2003 Michigan Association for Infant Mental Health.