Neonatal Multisensory Processing in Preterm and Term Infants Predicts Sensory Reactivity and Internalizing Tendencies in Early Childhood

The impact of premature birth on auditory-visual processes in very preterm schoolchildren

Interactions between stimuli from different sensory modalities and their integration are central to daily life, contributing to improved perception. Being born prematurely and the subsequent hospitalization can have an impact not only on sensory processes, but also on the manner in which information from different senses is combined-i.e., multisensory processes. Very preterm (VPT) children (<32 weeks gestational age) present impaired multisensory processes in early childhood persisting at least through the age of five. However, it remains largely unknown whether and how these consequences persist into later childhood. Here, we evaluated the integrity of auditory-visual multisensory processes in VPT schoolchildren. VPT children (N = 28; aged 8-10 years) received a standardized cognitive assessment and performed a simple detection task at their routine follow-up appointment. The simple detection task involved pressing a button as quickly as possible upon presentation of an auditory, visual, or simultaneous audio-visual stimulus. Compared to full-term (FT) children (N = 23; aged 6-11 years), reaction times of VPT children were generally slower and more variable, regardless of sensory modality. Nonetheless, both groups exhibited multisensory facilitation on mean reaction times and inter-quartile ranges. There was no evidence that standardized cognitive or clinical measures correlated with multisensory gains of VPT children. However, while gains in FT children exceeded predictions based on probability summation and thus forcibly invoked integrative processes, this was not the case for VPT children. Our findings provide evidence of atypical multisensory profiles in VPT children persisting into school-age. These results could help in targeting supportive interventions for this vulnerable population.

Microstate Analysis of Continuous Infant EEG: Tutorial and Reliability

Microstate analysis of resting-state EEG is a unique data-driven method for identifying patterns of scalp potential topographies, or microstates, that reflect stable but transient periods of synchronized neural activity evolving dynamically over time. During infancy - a critical period of rapid brain development and plasticity - microstate analysis offers a unique opportunity for characterizing the spatial and temporal dynamics of brain activity. However, whether measurements derived from this approach (e.g., temporal properties, transition probabilities, neural sources) show strong psychometric properties (i.e., reliability) during infancy is unknown and key information for advancing our understanding of how microstates are shaped by early life experiences and whether they relate to individual differences in infant abilities. A lack of methodological resources for performing microstate analysis of infant EEG has further hindered adoption of this cutting-edge approach by infant researchers. As a result, in the current study, we systematically addressed these knowledge gaps and report that most microstate-based measurements of brain organization and functioning except for transition probabilities were stable with four minutes of video-watching resting-state data and highly internally consistent with just one minute. In addition to these results, we provide a step-by-step tutorial, accompanying website, and open-access data for performing microstate analysis using a free, user-friendly software called Cartool. Taken together, the current study supports the reliability and feasibility of using EEG microstate analysis to study infant brain development and increases the accessibility of this approach for the field of developmental neuroscience.

Synchrony perception across senses: A systematic review of temporal binding window changes from infancy to adolescence in typical and atypical development

Sensory integration is increasingly acknowledged as being crucial for the development of cognitive and social abilities. However, its developmental trajectory is still little understood. This systematic review delves into the topic by investigating the literature about the developmental changes from infancy through adolescence of the Temporal Binding Window (TBW) - the epoch of time within which sensory inputs are perceived as simultaneous and therefore integrated. Following comprehensive searches across PubMed, Elsevier, and PsycInfo databases, only experimental, behavioral, English-language, peer-reviewed studies on multisensory temporal processing in 0-17-year-olds have been included. Non-behavioral, non-multisensory, and non-human studies have been excluded as those that did not directly focus on the TBW. The selection process was independently performed by two Authors. The 39 selected studies involved 2859 participants in total. Findings indicate a predisposition towards cross-modal asynchrony sensitivity and a composite, still unclear, developmental trajectory, with atypical development associated to increased asynchrony tolerance. These results highlight the need for consistent and thorough research into TBW development to inform potential interventions.

Inter-hemispheric somatosensory coherence and parental stress in hypersensitivity at 8 months old: An electroencephalography study

OBJECTIVE

Infant hypersensitivity affects daily challenges and parental stress. Although the crucial role of tactile sensation in infants' brain function has been highlighted, hypersensitive infants and their families lack support. Electroencephalography may be useful for understanding hypersensitivity traits. We investigated the relationship between infant perceptual hypersensitivity and parental stress, somatosensory-evoked potential (SEP), and magnitude-squared coherence (MSC) in the general population.

METHODS

Infants aged 8 months (n = 63) were evaluated for hypersensitivity and parental stress using a questionnaire and for cortical activity using electroencephalography. Vibration stimuli were applied to the infant's left foot. SEP components that peaked around 150 ms (N2) and at 200 ms (P2) after stimulus onset were evaluated by amplitude and latency at the midline electrode (Cz) and MSC between the midline electrodes (C3-C4).

RESULTS

Parental stress was associated with infant hypersensitivity. The latency of Cz was delayed, and C3-C4 delta MSC was high in infants with hypersensitivity.

CONCLUSIONS

Increasing inter-hemispheric MSC synchrony in the stimulated condition in infants with hypersensitivity suggested atypical somatosensory cortical function.

SIGNIFICANCE

These findings contribute to identifying, understanding the mechanisms of, and developing effective coping strategies for early-stage hypersensitivity.

Longstanding Auditory Sensory and Semantic Differences in Preterm Born Children

More than 10% of births are preterm, and the long-term consequences on sensory and semantic processing of non-linguistic information remain poorly understood. 17 very preterm-born children (born at < 33 weeks gestational age) and 15 full-term controls were tested at 10 years old with an auditory object recognition task, while 64-channel auditory evoked potentials (AEPs) were recorded. Sounds consisted of living (animal and human vocalizations) and manmade objects (e.g. household objects, instruments, and tools). Despite similar recognition behavior, AEPs strikingly differed between full-term and preterm children. Starting at 50ms post-stimulus onset, AEPs from preterm children differed topographically from their full-term counterparts. Over the 108-224ms post-stimulus period, full-term children showed stronger AEPs in response to living objects, whereas preterm born children showed the reverse pattern; i.e. stronger AEPs in response to manmade objects. Differential brain activity between semantic categories could reliably classify children according to their preterm status. Moreover, this opposing pattern of differential responses to semantic categories of sounds was also observed in source estimations within a network of occipital, temporal and frontal regions. This study highlights how early life experience in terms of preterm birth shapes sensory and object processing later on in life.

The emergence of the multisensory brain: From the womb to the first steps

The becoming of the human being is a multisensory process that starts in the womb. By integrating spontaneous neuronal activity with inputs from the external world, the developing brain learns to make sense of itself through multiple sensory experiences. Over the past ten years, advances in neuroimaging and electrophysiological techniques have allowed the exploration of the neural correlates of multisensory processing in the newborn and infant brain, thus adding an important piece of information to behavioral evidence of early sensitivity to multisensory events. Here, we review recent behavioral and neuroimaging findings to document the origins and early development of multisensory processing, particularly showing that the human brain appears naturally tuned to multisensory events at birth, which requires multisensory experience to fully mature. We conclude the review by highlighting the potential uses and benefits of multisensory interventions in promoting healthy development by discussing emerging studies in preterm infants.

Development and experience-dependence of multisensory spatial processing

Multisensory spatial processes are fundamental for efficient interaction with the world. They include not only the integration of spatial cues across sensory modalities, but also the adjustment or recalibration of spatial representations to changing cue reliabilities, crossmodal correspondences, and causal structures. Yet how multisensory spatial functions emerge during ontogeny is poorly understood. New results suggest that temporal synchrony and enhanced multisensory associative learning capabilities first guide causal inference and initiate early coarse multisensory integration capabilities. These multisensory percepts are crucial for the alignment of spatial maps across sensory systems, and are used to derive more stable biases for adult crossmodal recalibration. The refinement of multisensory spatial integration with increasing age is further promoted by the inclusion of higher-order knowledge.

Maternal Voice and Tactile Stimulation Modulate Oxytocin in Mothers of Hospitalized Preterm Infants: A Randomized Crossover Trial

Prematurity is a major risk factor for perinatal stress and neonatal complications leading to systemic inflammation and abnormal mother-infant interactions. Oxytocin (OT) is a neuropeptide regulating the inflammatory response and promoting mother-infant bonding. The release of this hormone might be influenced by either vocal or tactile stimulation. The main objective of the current randomized, crossover, clinical trial was to assess the salivary OT/cortisol balance in mothers following the exposure of their baby born preterm to two types of sensorial interventions: maternal voice without or with contingent tactile stimulation provided by the mother to her infant. Among the 26 mothers enrolled, maternal voice intervention alone had no effect on OT and cortisol levels in the mothers, but when associated with tactile stimulation, it induced a significant increase in maternal saliva oxytocin (38.26 ± 30.26 pg/mL before vs 53.91 ± 48.84 pg/mL after, p = 0.02), particularly in the mothers who delivered a female neonate. Maternal voice intervention induced a significant reduction in cortisol and an increase in OT levels in mothers when the maternal voice with a tactile stimulation intervention was performed first. In conclusion, exposure to the maternal voice with a contingent tactile stimulation was associated with subtle changes in the maternal hormonal balance between OT and cortisol. These findings need to be confirmed in a larger sample size and may ultimately guide caregivers in providing the best intervention to reduce parental stress following preterm delivery.

Development of neonatal brain functional centrality and alterations associated with preterm birth

Formation of the functional connectome in early life underpins future learning and behavior. However, our understanding of how the functional organization of brain regions into interconnected hubs (centrality) matures in the early postnatal period is limited, especially in response to factors associated with adverse neurodevelopmental outcomes such as preterm birth. We characterized voxel-wise functional centrality (weighted degree) in 366 neonates from the Developing Human Connectome Project. We tested the hypothesis that functional centrality matures with age at scan in term-born babies and is disrupted by preterm birth. Finally, we asked whether neonatal functional centrality predicts general neurodevelopmental outcomes at 18 months. We report an age-related increase in functional centrality predominantly within visual regions and a decrease within the motor and auditory regions in term-born infants. Preterm-born infants scanned at term equivalent age had higher functional centrality predominantly within visual regions and lower measures in motor regions. Functional centrality was not related to outcome at 18 months old. Thus, preterm birth appears to affect functional centrality in regions undergoing substantial development during the perinatal period. Our work raises the question of whether these alterations are adaptive or disruptive and whether they predict neurodevelopmental characteristics that are more subtle or emerge later in life.

A Comparison of the Clinical Presentation of Preterm Birth and Autism Spectrum Disorder: Commonalities and Distinctions in Children Under 3

Premature infants and infants later diagnosed with autism spectrum disorder (ASD) share many commonalities in clinical presentations. However, prematurity and ASD also have differences in clinical presentation. These overlapping phenotypes can lead to misdiagnoses of ASD or missing a diagnosis of ASD in preterm infants. We document these commonalities and differences in various developmental domains with the hope of aiding in the accurate early detection of ASD and timely intervention implementation in children born premature. Given the degree of similarities in presentation, evidence-based interventions designed specifically for preterm toddlers or toddlers with ASD may ultimately aid both populations.

Microstate analysis in infancy

BACKGROUND

Microstate analysis is an emerging method for investigating global brain connections using electroencephalography (EEG). Microstates have been colloquially referred to as the "atom of thought," meaning that from these underlying networks comes coordinated neural processing and cognition. The present study examined microstates at 6-, 8-, and 10-months of age. It was hypothesized that infants would demonstrate distinct microstates comparable to those identified in adults that also parallel resting-state networks using fMRI. An additional exploratory aim was to examine the relationship between microstates and temperament, assessed via parent reports, to further demonstrate microstate analysis as a viable tool for examining the relationship between neural networks, cognitive processes as well as emotional expression embodied in temperament attributes.

METHODS

The microstates analysis was performed with infant EEG data when the infant was either 6- (n = 12), 8- (n = 16), or 10-months (n = 6) old. The resting-state task involved watching a 1-minute video segment of Baby Einstein while listening to the accompanying music. Parents completed the IBQ-R to assess infant temperament.

RESULTS

Four microstate topographies were extracted. Microstate 1 had an isolated posterior activation; Microstate 2 had a symmetric occipital to prefrontal orientation; Microstate 3 had a left occipital to right frontal orientation; and Microstate 4 had a right occipital to left frontal orientation. At 10-months old, Microstate 3, thought to reflect auditory/language processing, became activated more often, for longer periods of time, covering significantly more time across the task and was more likely to be transitioned into. This finding is interpreted as consistent with language acquisition and phonological processing that emerges around 10-months. Microstate topographies and parameters were also correlated with differing temperament broadband and narrowband scales on the IBQ-R.

CONCLUSION

Three microstates emerged that appear comparable to underlying networks identified in adult and infant microstate literature and fMRI studies. Each of the temperament domains was related to specific microstates and their parameters. These networks also correspond with auditory and visual processing as well as the default mode network found in prior research and can lead to new investigations examining differences across stimulus presentations to further explain how infants begin to recognize, respond to, and engage with the world around them.

Efficacy of Breast Milk Olfactory and Gustatory Interventions on Neonates’ Biobehavioral Responses to Pain during Heel Prick Procedures

This study aimed to evaluate the efficacy of breast milk odor either alone or in combination with breast milk taste (via syringe-feeding) to alleviate neonates’ biobehavioral responses to pain during heel-prick procedures. This prospective randomized controlled trial recruited 114 neonates by convenience sampling from a newborn unit of a medical center in Taiwan. Neonates were randomly assigned to three groups: control (gentle touch + human voice), control + breast milk odor, and control + breast milk odor + breast milk taste. Heart rate, oxygen saturation, and voice recordings of crying were measured across heel-prick procedures: baseline, no stimuli (stage 0); during heel prick (Stages 1–4); and recovery (Stages 5–10). Generalized estimating equations and Kaplan–Meier survival analysis compared differences in changes between groups for heart rate, oxygen saturation, and time to crying cessation. Changes in mean heart rate and oxygen saturation in neonates receiving breast milk odor or breast milk odor + breast milk taste were significantly less than those at the corresponding stage for the control group. Among neonates receiving breast milk odor or breast milk odor + breast milk taste, hazard rate ratios for crying cessation were 3.016 and 6.466, respectively. Mother’s breast milk olfactory and gustatory interventions could stabilize the biobehavioral responses to pain during heel prick procedures in neonates.

[Preterm birth: a risk for mental health?]

One in 12 children is born before 37 completed weeks of gestation and during the last decades survival rates and developmental outcomes of even very premature children have significantly improved. As a result, mental health sequelae of preterm birth are more frequently addressed. The manifestation of a distinct psychopathological profile with co-occurrence of symptoms associated with attention deficit/hyperactivity, autism spectrum and anxiety disorders has been recognized and discussed as "preterm behavioral phenotype", mainly affecting high-risk children with very low birth weights. Current research findings on parental psychological distress and early childhood developmental conditions after preterm birth indicate contextual factors that are of relevance, also for clinicians in psychotherapeutic practice.

Wiring of higher-order cortical areas: Spatiotemporal development of cortical hierarchy

A hierarchical development of cortical areas was suggested over a century ago, but the diversity and complexity of cortical hierarchy properties have so far prevented a formal demonstration. The aim of this review is to clarify the similarities and differences in the developmental processes underlying cortical development of primary and higher-order areas. We start by recapitulating the historical and recent advances underlying the biological principle of cortical hierarchy in adults. We then revisit the arguments for a hierarchical maturation of cortical areas, and further integrate the principles of cortical areas specification during embryonic and postnatal development. We highlight how the dramatic expansion in cortical size might have contributed to the increased number of association areas sustaining cognitive complexification in evolution. Finally, we summarize the recent observations of an alteration of cortical hierarchy in neuropsychiatric disorders and discuss their potential developmental origins.

Sensory Stimulation in the NICU Environment: Devices, Systems, and Procedures to Protect and Stimulate Premature Babies

Prematurity deprives infants of the prenatal sensory stimulation essential to their correct development; in addition, the stressful environment of the NICU impacts negatively on their growth. The purpose of this review was to investigate the effects of NICU noise pollution on preterm infants and parents. We focused on the systems and projects used to control and modulate sounds, as well as on those special devices and innovative systems used to deliver maternal sounds and vibrations to this population. The results showed beneficial effects on the preterm infants in different areas such as physiological, autonomic, and neurobehavioral development. Although most of these studies highlight positive reactions, there is also a general acknowledgement of the current limits: small and heterogeneous groups, lack of structured variable measurements, systematic control groups, longitudinal studies, and normative values. The mother's presence is always preferred, but the use of music therapy and the devices analyzed, although not able to replace her presence, aim to soften her absence through familiar and protective stimuli, which is a very powerful aid during the COVID-19 pandemic.

Spatial tuning of electrophysiological responses to multisensory stimuli reveals a primitive coding of the body boundaries in newborns

The ability to identify our own body and its boundaries is crucial for survival. Ideally, the sooner we learn to discriminate external stimuli occurring close to our body from those occurring far from it, the better (and safer) we may interact with the sensory environment. However, when this mechanism emerges within ontogeny is unknown. Is it something acquired throughout infancy, or is it already present soon after birth? The presence of a spatial modulation of multisensory integration (MSI) is considered a hallmark of a functioning representation of the body position in space. Here, we investigated whether MSI is present and spatially organized in 18- to 92-h-old newborns. We compared electrophysiological responses to tactile stimulation when concurrent auditory events were delivered close to, as opposed to far from, the body in healthy newborns and in a control group of adult participants. In accordance with previous studies, adult controls showed a clear spatial modulation of MSI, with greater superadditive responses for multisensory stimuli close to the body. In newborns, we demonstrated the presence of a genuine electrophysiological pattern of MSI, with older newborns showing a larger MSI effect. Importantly, as for adults, multisensory superadditive responses were modulated by the proximity to the body. This finding may represent the electrophysiological mechanism responsible for a primitive coding of bodily self boundaries, thus suggesting that even just a few hours after birth, human newborns identify their own body as a distinct entity from the environment.