Experimental Evidence of Structural Representation of Hands in Early Infancy

Maternal interoceptive focus is associated with greater reported engagement in mother-infant stroking and rocking

Parental caregiving during infancy is primarily aimed at the regulation of infants' physiological and emotional states. Recent models of embodied cognition propose that interoception, i.e., the perception of internal bodily states, may influence the quality and quantity of parent-infant caregiving. Yet, empirical investigations into this relationship remain scarce. Across two online studies of mothers with 6- to 18-month-old infants during Covid-19 lockdowns, we examined whether mothers' self-reported engagement in stroking and rocking their infant was related to self-reported interoceptive abilities. Additional measures included retrospective accounts of pregnancy and postnatal body satisfaction, and mothers' reports of their infant's understanding of vocabulary relating to body parts. In Study 1 (N = 151) and Study 2 (N = 111), mothers reported their engagement in caregiving behaviours and their tendency to focus on and regulate bodily states. In a subsample from Study 2 (N = 49), we also obtained an objective measure of cardiac interoceptive accuracy using an online heartbeat counting task. Across both studies, the tendency to focus on and regulate interoceptive states was associated with greater mother-infant stroking and rocking. Conversely, we found no evidence for a relationship between objective interoceptive accuracy and caregiving. The findings suggest that interoception may play a role in parental engagement in stroking and rocking, however, in-person dyadic studies are warranted to further investigate this relationship.

Importance of body representations in social-cognitive development: New insights from infant brain science

There is significant interest in the ways the human body, both one's own and that of others, is represented in the human brain. In this chapter we focus on body representations in infancy and synthesize relevant findings from both infant cognitive neuroscience and behavioral experiments. We review six experiments in infant neuroscience that have used novel EEG and MEG methods to explore infant neural body maps. We then consider results from behavioral studies of social imitation and examine what they contribute to our understanding of infant body representations at a psychological level. Finally, we interweave both neuroscience and behavioral lines of research to ground new theoretical claims about early infant social cognition. We propose, based on the evidence, that young infants can represent the bodily acts of others and their own bodily acts in commensurate terms. Infants initially recognize correspondences between self and other-they perceive that others are "like me" in terms of bodies and bodily actions. This capacity for registering and using self-other equivalence mappings has far-reaching implications for mechanisms of developmental change. Infants can learn about the affordances and powers of their own body by watching adults' actions and their causal consequences. Reciprocally, infants can enrich their understanding of other people's internal states by taking into account the way they themselves feel when they perform similar acts. The faces, bodies, and matching actions of people are imbued with unique meaning because they can be mapped to the infant's own body and behavior.

Body representation in infants: Categorical boundaries of body parts as assessed by somatosensory mismatch negativity

There is growing interest in developing and using novel measures to assess how the body is represented in human infancy. Various lines of evidence with adults and older children show that tactile perception is modulated by a high-level representation of the body. For instance, the distance between two points of tactile stimulation is perceived as being greater when these points cross a joint boundary than when they are within a body part, suggesting that the representation of the body is structured with joints acting as categorical boundaries between body parts. Investigating the developmental origins of this categorical effect has been constrained by infants’ inability to verbally report on the properties of tactile stimulation. Here we made novel use of an infant brain measure, the somatosensory mismatch negativity (sMMN), to explore categorical aspects of tactile body processing in infants aged 6–7 months. Amplitude of the sMMN elicited by tactile stimuli across the wrist boundary was significantly greater than for stimuli of equal distance that were within the boundary, suggesting a categorical effect in body processing in infants. We suggest that an early-appearing, structured representation of the body into ‘parts’ may play a role in mapping correspondences between self and other.

Brain-Inspired Coding of Robot Body Schema Through Visuo-Motor Integration of Touched Events

Representing objects in space is difficult because sensorimotor events are anchored in different reference frames, which can be either eye-, arm-, or target-centered. In the brain, Gain-Field (GF) neurons in the parietal cortex are involved in computing the necessary spatial transformations for aligning the tactile, visual and proprioceptive signals. In reaching tasks, these GF neurons exploit a mechanism based on multiplicative interaction for binding simultaneously touched events from the hand with visual and proprioception information.By doing so, they can infer new reference frames to represent dynamically the location of the body parts in the visual space (i.e., the body schema) and nearby targets (i.e., its peripersonal space). In this line, we propose a neural model based on GF neurons for integrating tactile events with arm postures and visual locations for constructing hand- and target-centered receptive fields in the visual space. In robotic experiments using an artificial skin, we show how our neural architecture reproduces the behaviors of parietal neurons (1) for encoding dynamically the body schema of our robotic arm without any visual tags on it and (2) for estimating the relative orientation and distance of targets to it. We demonstrate how tactile information facilitates the integration of visual and proprioceptive signals in order to construct the body space.