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

   https://doi.org/10.1111/desc.12698  

   Meltzoff, Andrew N. ; Saby, Joni N. ; Marshall, Peter J. ( June 2018 , Developmental Science)

   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.

    

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2. Using somatosensory mismatch responses as a window into somatotopic processing of tactile stimulation

   https://doi.org/10.1111/psyp.13030  

   Shen, Guannan ; Smyk, Nathan J. ; Meltzoff, Andrew N. ; Marshall, Peter J. ( November 2017 , Psychophysiology)

   Brain responses to tactile stimulation have often been studied through the examination of ERPs elicited to touch on the body surface. Here, we examined two factors potentially modulating the amplitude of the somatosensory mismatch negativity (sMMN) and P300 responses elicited by touch to pairs of body parts: (a) the distance between the representation of these body parts in somatosensory cortex, and (b) the physical distances between the stimulated points on the body surface. The sMMN and the P300 response were elicited by tactile stimulation in two oddball protocols. One protocol leveraged a discontinuity in cortical somatotopic organization, and involved stimulation of either the neck or the hand in relation to stimulation of the lip. The other protocol involved stimulation to the third or fifth finger in relation to the second finger. The neck‐lip pairing resulted in significantly larger sMMN responses (with shorter latencies) than the hand‐lip pairing, whereas the reverse was true for the amplitude of the P300. Mean sMMN amplitude and latency did not differ between finger pairings. However, larger P300 responses were elicited to stimulation of the fifth finger than the third finger. These results suggest that, for certain combinations of body parts, early automatic somatosensory mismatch responses may be influenced by distance between the cortical representations of these body parts, whereas the later P300 response may be more influenced by the distance between stimulated body parts on the body surface. Future investigations can shed more light on this novel suggestion.

    

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3. Body maps in the infant brain: implications for neurodevelopmental disabilities

   https://doi.org/10.1111/dmcn.14540  

   Marshall, Peter J. ; Meltzoff, Andrew N. ( April 2020 , Developmental Medicine & Child Neurology)

   This review and synthesis discusses recent work that has utilized brain imaging methods, such as the electroencephalogram (EEG) and magnetoencephalogram, to provide insights into the ways that the body is represented in the infant brain. One aspect of body representation concerns somatotopic maps of the body surface in somatosensory cortex. A good deal is known about the properties of these maps in adults, but there has been relatively little developmental work. Recent studies have provided new insights into the organization of infant neural body maps and have laid the foundations for examining their plasticity in relation to behavioral development. Other work has suggested that neural body maps may be involved in the registration of correspondences between self and other, with implications for early social development. Here, body representations are discussed in the context of preterm birth and autism spectrum disorder, providing novel perspectives relevant to developmental medicine and child neurology.

   Somatotopic body maps develop prenatally through intrinsic and activity‐dependent mechanisms.

   There is increasing interest in understanding postnatal plasticity in body maps.

   Body representations may be involved in the registration of preverbal, interpersonal relationships.

    

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4. All in the Family – Touch Versus Olfaction in Moles

   https://doi.org/10.1002/ar.24057  

   Catania, Kenneth C. ( February 2019 , The Anatomical Record)

   Here I review, compare, and contrast the neurobiology and behavior of the common, eastern mole (Scalopus aquaticus) and the star‐nosed mole (Condylura cristata). These two species are part of the same family (Talpidae) and have similar body size and general morphology. But they differ in sensory specializations, complexity of neocortical organization, and behavior. The star‐nosed mole has an elaborate mechanosensory organ—the star—consisting of 22 epidermal appendages (rays) covered with 25,000 touch domes called Eimer's organs. This densely innervated structure is represented in the neocortex in three different somatosensory maps, each visible in flattened neocortical sections as a series of 11 modules representing the 11 rays from the contralateral body. The 11th ray is greatly magnified in primary somatosensory cortex (S1). Behavioral studies show the star is moved in a saccadic manner and the 11th ray is a high‐resolution tactile fovea, allowing star‐nosed moles to forage on small prey with unprecedented speed and efficiency. In contrast, common mole noses lack Eimer's organs, their neocortex contains only two cortical maps of the nose, and they cannot localize small prey. Yet common moles have exceptional olfactory abilities, sniffing in stereo to rapidly localize discrete odor sources originating from larger prey. In addition, common moles are shown to track odorant trails laid down by moving prey. These results highlight the surprising abilities of species once thought to be simple, and the usefulness of diverse species in revealing general principles of brain organization and behavior. Anat Rec, 2019. © 2019 American Association for Anatomy.

    

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5. Love on the developing brain: Maternal sensitivity and infants’ neural responses to emotion in the dorsolateral prefrontal cortex

   https://doi.org/10.1111/desc.13497  

   Stern, Jessica A. ; Kelsey, Caroline M. ; Yancey, Heath ; Grossmann, Tobias ( March 2024 , Developmental Science)

   Infancy is a sensitive period of development, during which experiences of parental care are particularly important for shaping the developing brain. In a longitudinal study ofN = 95 mothers and infants, we examined links between caregiving behavior (maternal sensitivity observed during a mother–infant free‐play) and infants’ neural response to emotion (happy, angry, and fearful faces) at 5 and 7 months of age. Neural activity was assessed using functional Near‐Infrared Spectroscopy (fNIRS) in the dorsolateral prefrontal cortex (dlPFC), a region involved in cognitive control and emotion regulation. Maternal sensitivity was positively correlated with infants’ neural responses tohappyfaces in the bilateral dlPFC and was associated with relative increases in such responses from 5 to 7 months. Multilevel analyses revealed caregiving‐related individual differences in infants’ neural responses to happy compared to fearful faces in the bilateral dlPFC, as well as other brain regions. We suggest that variability in dlPFC responses to emotion in the developing brain may be one correlate of early experiences of caregiving, with implications for social‐emotional functioning and self‐regulation.

    

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