Visual fixation in human newborns correlates with extensive white matter networks and predicts long-term neurocognitive development

The eyes have it: neurobiological roots, developmental trajectories, and social significance of mutual gaze in early parent-infant interactions

Mutual Gaze (MG) plays a crucial role in early interactions, yet there is no clear terminological or conceptual definition, highlighting the need for consensus on its onset, development, and clinical implications. This review aims to provide new insights into the extent and the way in which MG develops during early mother-infant interactions, both typically and atypically, and how it may be associated with a child's future social, cognitive, and behavioral development. A PICO format was employed, a systematic literature search was conducted, and 28 studies were selected for review. These studies varied in their terminological definitions of MG, sample sizes, participants' characteristics, and methodologies. Results were analyzed through thematic analysis, leading to the identification of four main themes: neurobiological correlates of MG, developmental changes in MG during the first year of life, the involvement of MG in social interaction, and MG in atypical neurodevelopment. The findings showed that MG is regulated by underlying neurobiological processes, leading to specific behavioral and interactive modalities, which evolve over time during the first year and are positively associated with attentional and socio-emotional self-regulatory skills. Additionally, MG exhibits distinct behavioral characteristics in certain neurodevelopmental conditions, such as preterm infants and those with Autism Spectrum Disorder (ASD), and may serve as a potential behavioral marker of ASD in infants older than 6 months, although further data are needed to draw definitive conclusions.

Charting brain functional development from birth to 6 years of age

Early childhood is crucial for brain functional development. Using advanced neuroimaging methods, characterizing functional connectivity has shed light on the developmental process in infants. However, insights into spatiotemporal functional maturation from birth to early childhood are substantially lacking. In this study, we aggregated 1,091 resting-state functional MRI scans of typically developing children from birth to 6 years of age, harmonized the cohort and imaging-state-related bias, and delineated developmental charts of functional connectivity within and between canonical brain networks. These charts revealed potential neurodevelopmental milestones and elucidated the complex development of brain functional integration, competition and transition processes. We further determined that individual deviations from normative growth charts are significantly associated with infant cognitive abilities. Specifically, connections involving the primary, default, control and attention networks were key predictors. Our findings elucidate early neurodevelopment and suggest that functional connectivity-derived brain charts may provide an effective tool to monitor normative functional development.

A light in the darkness: Early phases of development and the emergence of cognition

During the prenatal period, the major brain development milestones are posed and calibrated through different mechanisms, among which endogenous activity, that prepares the "system" to face the external environment. However, the specific nature of the human nervous system, intended for brain plasticity that is varied by brain area and prolonged over time, requires much time for environmental experiences to shape the cerebral circuitries. Therefore, the neonate completely depends on the caregiver, and during the first months of postnatal life, it exhibits a transitory and limited repertoire of behaviors and skills that favors the mother in her new role. This transitory condition will gradually give way to more mature competencies, the milestones of which are posed within 2 years of age. This review takes a new perspective on early development and attempts to trace the remarkable changes from in-utero period to the second year of postnatal life, posing a bridge between the neurobiological substrate and behavioral development. We based our work on the "normal" development, pointing out the risks inherent in any development process.

Natural history of cerebral visual impairment in children with cerebral palsy

AIM

To longitudinally evaluate the natural history of cerebral visual impairment (CVI) in children with cerebral palsy (CP) and identify which early visual signs or symptoms are associated with cognitive visual disorders (CVDs) at school age.

METHOD

Fifty-one individuals with CP and CVI underwent an ophthalmological, oculomotor, and basic visual function evaluation at three time points: T0 (6-35 months old); T1 (3-5 years old); and T2 (≥6 years old). We also performed a cognitive visual evaluation at T2. Logistic regression fitted using a generalized estimation equation (binary) and cumulative link models (ordinal) were used to model the outcomes of interest.

RESULTS

Ophthalmological deficits were stable over time, except for ocular fundus abnormalities (T1-T0, p = 0.01; T2-T1, p = 0.02; T2-T0, p < 0.01) and strabismus, whose frequency increased with age (T2-T0, p= 0.02 with T2-T0, p = 0.05). Conversely, fixation (T1-T0, T2-T0, p < 0.01), smooth pursuit (T2-T1, T2-T0, p < 0.01), saccades (T1-T0, T2-T1, T2-T0, p < 0.01), as well as visual acuity, contrast sensitivity, and visual field (T1-T0, T2-T0, p < 0.01) all improved over time. Early oculomotor dysfunction was associated with CVD at T2.

INTERPRETATION

Although a diagnosis of CVI was confirmed in all children at each time point, several visual signs and symptoms improved over time; in some cases, they reached complete recovery at T1 and T2. These results emphasize the 'permanent' but 'not unchanging' nature of the CVI associated with CP during development.

The developing visual system: A building block on the path to autism

Longitudinal neuroimaging studies conducted over the past decade provide evidence of atypical visual system development in the first years of life in autism spectrum disorder (ASD). Findings from genomic analyses, family studies, and postmortem investigations suggest that changes in the visual system in ASD are linked to genetic factors, making the visual system an important neural phenotype along the path from genes to behavior that deserves further study. This article reviews what is known about the developing visual system in ASD in the first years of life; it also explores the potential canalizing role that atypical visual system maturation may have in the emergence of ASD by placing findings in the context of developmental cascades involving brain development, attention, and social and cognitive development. Critical gaps in our understanding of human visual system development are discussed, and future research directions are proposed to improve our understanding of ASD as a complex neurodevelopmental disorder with origins in early brain development.

The mother-child interface: A neurobiological metamorphosis

From the start of pregnancy, mother and child induce reciprocal neurobiological changes in the brain that will prove critical for neurodevelopment and survival of both. Molecular communication between mother and fetus is constantly active and persists even after the fetus starts to synthesize its hormones in late gestation. Intriguingly, some mother and fetus exchange cells remain in the other's brain and body with long-lasting effects and memories that do not follow the laws of classical genetics but involve complex epigenetic mechanisms. After childbirth, mother and child go through a transitional phase, a sort of limbo in which both will have a peculiar functioning profile, which is adaptive for contingencies but also renders them vulnerable. The interplay between these two "limbo" states allows for an easier transition to the subsequent phases of development. In this review, we will trace mother's and child's path from pregnancy to the months following birth and, in particular, unravel i) the key features of pregnancy and brain development and the reciprocal influences; ii) how a transitory pattern of functioning characterize mother and child, moving them toward more flexible and evolved forms; and iii) how mother and fetus act during childbirth to promote neuroprotection, pain reduction, and neurophysiological changes. Therefore, this review covers a wide range of topics, integrating neuroanatomical, neurological, biochemical, neurophysiological, and psychological studies in a meaningful way, trying to integrate them in a holistic view of the mother-child interface that is usually neglected.

Relationship between maternal biological features, environmental factors, and newborn neuromotor development associated with visual fixation abilities

Newborn visual fixation abilities predict future cognitive, perceptive, and motor skills. However, little is known about the factors associated with the newborn visual fixation, which is an indicator of neurocognitive abilities. We analyzed maternal biological and environmental characteristics associated with fine motor skills (visual tracking) in 1 month old infants. Fifty-one infants were tested on visual tracking tasks (Infant Visuomotor Behavior Assessment Scale/ Guide for the Assessment of Visual Ability in Infants) and classified according to visual conducts scores. Differences between groups were compared considering motor development (Alberta Infant Motor Scale) maternal mental health (Edinburgh Postnatal Depression Scale and Hamilton Anxiety Scale); home environment (Affordances in the Home Environment for Development Scale); maternal care (Coding Interactive Behavior); breastmilk composition (total fatty acids, proteins, and cortisol); and maternal metabolic profile (serum hormones and interleukins). Mothers of infants with lower visual fixation scores had higher levels of protein in breastmilk at 3 months. Mothers of infants with better visual conduct scores had higher serum levels of T4 (at 1 month) and prolactin (at 3 months). There were no associations between visual ability and motor development, home environment, or maternal care. Early newborn neuromotor development, especially visual and fine motor skills, is associated with maternal biological characteristics (metabolic factors and breastmilk composition), highlighting the importance of early detection of maternal metabolic changes for the healthy neurodevelopment of newborns.

Correlation between Early Visual Functions and Cognitive Outcome in Infants at Risk for Cerebral Palsy or Other Neurodevelopmental Disorders: A Systematic Review

Early key visual skills, such as tracking objects, sustaining gaze, and shifting attention, rapidly develop within the first 6 months of infant life. These abilities play a significant role in the development of cognitive functions but are frequently compromised in infants at risk of developing neurodevelopmental disorders. This systematic review evaluates the potential of early vision function in the prediction of cognition at or above 12 months. Five databases were searched for relevant articles, and their quality was assessed with the Quality Assessment of Diagnostic Accuracy Studies tool. Eight studies were suitable, including 521 preterm-born infants at varying risk of developing Cerebral Palsy (CP). Each study showed a significant correlation between vision and cognitive outcome. Predictive analysis including sensitivity and specificity was possible for three studies. Methodological quality was variable. Sensitivity ranged between 57 and 100% in the vision function assessments items, while specificity ranged from 59 to 100%. In conclusion, early vision showed strong correlation with cognition ≥ 12 months. While no single vision assessment was found to be superior, evaluation of specific functions, namely fixation and following, both at term age and between 3 and 6 months, demonstrated strong predictive validity.

Visual alertness and brain diffusion tensor imaging at term age predict neurocognitive development at preschool age in extremely preterm-born children

INTRODUCTION

Cognitive development is characterized by the structural and functional maturation of the brain. Diffusion-weighted magnetic resonance imaging (dMRI) provides methods of investigating the brain structure and connectivity and their correlations with the neurocognitive outcome. Our aim was to examine the relationship between early visual abilities, brain white matter structures, and the later neurocognitive outcome.

METHODS

This study included 20 infants who were born before 28 gestational weeks and followed until the age of 6.5 years. At term age, visual alertness was evaluated and dMRI was used to investigate the brain white matter structure using fractional anisotropy (FA) in tract-based spatial statistics analysis. The JHU DTI white matter atlas was used to locate the findings. The neuropsychological assessment was used to assess neurocognitive performance at 6.5 years.

RESULTS

Optimal visual alertness at term age was significantly associated with better visuospatial processing (p < .05), sensorimotor functioning (p < .05), and social perception (p < .05) at 6.5 years of age. Optimal visual alertness related to higher FA values, and further, the FA values positively correlated with the neurocognitive outcome. The tract-based spatial differences in FA values were detected between children with optimal and nonoptimal visual alertness according to performance at 6.5 years.

CONCLUSION

We provide neurobiological evidence for the global and tract-based spatial differences in the white matter maturation between extremely preterm children with optimal and nonoptimal visual alertness at term age and a link between white matter maturation, visual alertness and the neurocognitive outcome at 6.5 years proposing that early visual function is a building block for the later neurocognitive development.

Extremely preterm children and relationships of minor neurodevelopmental impairments at 6 years

Aim

This study investigated minor impairments in neurological, sensorimotor, and neuropsychological functioning in extremely preterm-born (EPT) children compared to term-born children. The aim was to explore the most affected domains and to visualize their co-occurrences in relationship maps.

Methods

A prospective cohort of 56 EPT children (35 boys) and 37 term-born controls (19 boys) were assessed at a median age of 6 years 7 months with Touwen Neurological Examination, Movement Assessment Battery for Children, 2nd edition (MABC-2), Sensory Integration and Praxis Test (SIPT), and a Developmental Neuropsychological Assessment, 2nd edition (NEPSY-II). Altogether 20 test domains were used to illustrate the frequency of impaired test performances with a bar chart profile and to construct relationship maps of co-occurring impairments.

Results

The EPT children were more likely to perform inferiorly compared to the term-born controls across all assessments, with a wider variance and more co-occurring impairments. When aggregating all impaired test domains, 45% of the EPT children had more impaired domains than any term-born child (more than five domains, p &lt; 0.001). Relationship maps showed that minor neurological dysfunction (MND), NEPSY-II design copying, and SIPT finger identification constituted the most prominent relationship of co-occurring impairments in both groups. However, it was ten times more likely in the EPT group. Another relationship of co-occurring MND, impairment in NEPSY-II design copying, and NEPSY-II imitation of hand positions was present in the EPT group only.

Interpretation

Multiple minor impairments accumulate among EPT children at six years, suggesting that EPT children and their families may need support and timely multi-professional interventions throughout infancy and childhood.

Visual tracking at 4 months in preterm infants predicts 6.5-year cognition and attention

BACKGROUND

Visual tracking of moving objects requires sustained attention and prediction of the object's trajectory. We tested the hypothesis that measures of eye-head tracking of moving objects are associated to long-term neurodevelopment in very preterm infants.

METHODS

Visual tracking performance was assessed at 4 month's corrected age in 57 infants with gestational age <32 weeks. An object moved in front of the infant with sinusoidal or triangular (i.e. abrupt) turns of the direction. Gaze gain, smooth pursuit gain, and timing of gaze to object motion were analyzed. At 6.5 years the Wechsler Intelligence Scale for Children (WISC-IV), the Brown Attention Deficit Disorder (Brown ADD), and visual examination were performed.

RESULTS

Gaze gain and smooth pursuit gain at 4 months were strongly related to all WISC-IV parameters at 6.5 years. Gaze gain for the triangular and sinusoidal motion patterns related similarly to the cognitive scores. For the sinusoidal motion pattern, timing related to most Brown ADD parameters. There were no statistically significant differences in associations dependent on motion pattern. Visual function did not influence the results.

CONCLUSION

The ability to attend to and smoothly track a moving object in infancy is an early marker of cognition and attention at 6.5 years.

IMPACT

Potential long-term implications of infant visual tracking of moving objects for school-age neurodevelopment has not been previously studied in very preterm infants. Early coordination of eye and head movements in gaze gain, smooth pursuit, and timing of gaze to object motion are closely associated with cognition and attention at 6.5 years. As related functions at 6.5 years include perceptual and verbal skills, working memory, processing speed and attention, predictive elements in gaze tracking of moving objects might be a suitable target for future intervention studies.

Facilitating early parent-infant emotional connection improves cortical networks in preterm infants

Exposure to environmental adversities during early brain development, such as preterm birth, can affect early brain organization. Here, we studied whether development of cortical activity networks in preterm infants may be improved by a multimodal environmental enrichment via bedside facilitation of mother-infant emotional connection. We examined functional cortico-cortical connectivity at term age using high-density electroencephalography recordings in infants participating in a randomized controlled trial of Family Nurture Intervention (FNI). Our results identify several large-scale, frequency-specific network effects of FNI, most extensively in the alpha frequency in fronto-central cortical regions. The connectivity strength in this network was correlated to later neurocognitive performance, and it was comparable to healthy term-born infants rather than the infants receiving standard care. These findings suggest that preterm neurodevelopmental care can be improved by a biologically driven environmental enrichment, such as early facilitation of direct human connection.

Neural alterations in opioid-exposed infants revealed by edge-centric brain functional networks

Prenatal opioid exposure has been linked to adverse effects spanning multiple neurodevelopmental domains, including cognition, motor development, attention, and vision. However, the neural basis of these abnormalities is largely unknown. A total of 49 infants, including 21 opioid-exposed and 28 controls, were enrolled and underwent MRI (43 ± 6 days old) after birth, including resting state functional MRI. Edge-centric functional networks based on dynamic functional connections were constructed, and machine-learning methods were employed to identify neural features distinguishing opioid-exposed infants from unexposed controls. An accuracy of 73.6% (sensitivity 76.25% and specificity 69.33%) was achieved using 10 times 10-fold cross-validation, which substantially outperformed those obtained using conventional static functional connections (accuracy 56.9%). More importantly, we identified that prenatal opioid exposure preferentially affects inter- rather than intra-network dynamic functional connections, particularly with the visual, subcortical, and default mode networks. Consistent results at the brain regional and connection levels were also observed, where the brain regions and connections associated with visual and higher order cognitive functions played pivotal roles in distinguishing opioid-exposed infants from controls. Our findings support the clinical phenotype of infants exposed to opioids in utero and may potentially explain the higher rates of visual and emotional problems observed in this population. Finally, our findings suggested that edge-centric networks could better capture the neural differences between opioid-exposed infants and controls by abstracting the intrinsic co-fluctuation along edges, which may provide a promising tool for future studies focusing on investigating the effects of prenatal opioid exposure on neurodevelopment.

Phase-Based Cortical Synchrony Is Affected by Prematurity

Inter-areal synchronization by phase–phase correlations (PPCs) of cortical oscillations mediates many higher neurocognitive functions, which are often affected by prematurity, a globally prominent neurodevelopmental risk factor. Here, we used electroencephalography to examine brain-wide cortical PPC networks at term-equivalent age, comparing human infants after early prematurity to a cohort of healthy controls. We found that prematurity affected these networks in a sleep state-specific manner, and the differences between groups were also frequency-selective, involving brain-wide connections. The strength of synchronization in these networks was predictive of clinical outcomes in the preterm infants. These findings show that prematurity affects PPC networks in a clinically significant manner, suggesting early functional biomarkers of later neurodevelopmental compromise that may be used in clinical or translational studies after early neonatal adversity.

Newborn Neurobehavior Is Related to Later Neurodevelopment and Social Cognition Skills in Extremely Preterm-Born Children: A Prospective Longitudinal Cohort Study

Objective: The aim of this study was to evaluate the ability of the neonatal neurobehavioral characteristics to act as an indicator for later neurodevelopment and neurocognitive performance.

Methods: Sixty-six infants born extremely preterm (<28 gestational weeks) were followed until 6.5 years. Neurobehavior at term age was assessed by the behavior subscale of the Hammersmith Neonatal Neurological Examination (HNNE) using dichotomic rating, optimal, and non-optimal. The Griffiths Mental Developmental Scales (GMDS) at 2 years, and the Wechsler Intelligence Scales at 6.5 years, and a Neuropsychological Assessment at 6.5 years were used to assess neurodevelopment and neurocognitive performance including social cognition skills.

Results: An optimal auditory orientation at term age was associated with better developmental quotients (DQ) in Personal–Social, and Hearing–Language GMDS subscale at 2 years (p < 0.05). An optimal visual alertness was associated with better Total (p < 0.01), Locomotor (p < 0.001), and Eye–Hand Coordination (p < 0.01) DQs at 2 years, and with sensorimotor function (p < 0.001) and social perception (p < 0.01) tests at 6.5 years.

Conclusion: The neurobehavioral characteristics of newborns might serve as a precursor of social cognition skills and the HNNE behavior subscale offers a tool to identify infants at risk for later deficits in neurodevelopment and social cognition.

Home-based early stimulation program targeting visual and motor functions for preterm infants with delayed tracking: Feasibility of a Randomized Clinical Trial

AIMS

To verify the feasibility of a home-based early stimulation program targeting visual and motor functions in preterm infants with delayed visual tracking.

METHOD

We applied a randomized controlled trial. We included thirty low-risk preterm infants, from both genders, with delayed visual tracking, gestational between 28-37 weeks, and age at entrance between 1-2 months of corrected age, and absence of visual impairments. Infants were divided into two groups as follows: a) standard care group (SC) that received general orientation about sensory and motor development (16 infants); b) experimental group, that received a four-week home-based early stimulation program targeting visual and motor functions (ESPVM) applied by the caregivers (14 infants). The feasibility outcomes were retention and loss rates, adherence, adverse events, and stress signals. We obtained preliminary data by comparing visual tracking, motor development, and sensory behavior between groups at the end of the intervention.

RESULTS

Retention rate was high, 90 % of the caregivers provided ESPVM at least 22 days, and 70 % provided SC at least 17 days. No adverse events were reported. At the end of intervention, the ESPVM group presented higher frequencies of complete visual tracking for cards 7 (ESPVM = 57.3 %, SC = 6.3 %, p = 0.006) and 8 (ESPVM = 64.3 %, SC = 12.2 %, p = 0.013), and lower scores for total sensory profile (ESPVM: median = 58, range = 46-69; SC: median = 71, range = 54-90; p = 0.016). The groups were similar for motor development.

CONCLUSIONS

The protocol was feasible, and the results encourage a larger randomized controlled trial.

Early visuospatial attention and processing and related neurodevelopmental outcome at 2 years in children born very preterm

BACKGROUND

The ability to perceive and process visuospatial information is a condition for broader neurodevelopment. We examined the association of early visuospatial attention and processing with later neurodevelopmental outcome in very preterm infants.

METHODS

Visuospatial attention and processing was assessed in 209 children (<30 weeks gestation) using an easy applicable eye tracking-based paradigm at 1 and 2 years. Average reaction times to fixation (RTF) on specific visual stimuli were calculated, representing time needed for overall attention (Cartoon stimuli) and processing (Motion and Form stimuli). Associations between RTFs and various measures of development at 2 years including cognitive and motor development (Bayley Scales of Infant and Toddler Development-Third edition; Bayley-III), language (Lexi test) and behavior (Child Behavior Checklist) were examined.

RESULTS

At 1 year, 100 ms slower Cartoon and Motion RTFs were associated with lower cognitive Bayley-III scores (-4.4 points, 95%CI: -7.4; -1.5 and -1.0 points, -1.8; -0.2, respectively). A 100 ms slower Cartoon RTF was associated with a 3.5 (-6.6; -0.5) point decrease in motor Bayley-III score.

CONCLUSIONS

Visuospatial attention and motion processing at 1 year is predictive of overall cognitive and motor development 1 year later. The nonverbal eye tracking-based test can assist in early detection of preterm children at risk of adverse neurodevelopment.

IMPACT

Visuospatial attention and processing at 1 year corrected age is predictive for overall cognitive and motor development 1 year later in preterm infants. First study to relate early visuospatial attention and processing with later neurodevelopmental outcome in preterm children. Early detection of preterm children at risk of adverse neurodevelopment, which allows for more timely interventions.

Longtime Vision Function Prediction in Childhood Cataract Patients Based on Optical Coherence Tomography Images

The results of visual prediction reflect the tendency and speed of visual development during a future period, based on which ophthalmologists and guardians can know the potential visual prognosis in advance, decide on an intervention plan, and contribute to visual development. In our study, we developed an intelligent system based on the features of optical coherence tomography images for long-term prediction of best corrected visual acuity (BCVA) 3 and 5 years in advance. Two hundred eyes of 132 patients were included. Six machine learning algorithms were applied. In the BCVA predictions, small errors within two lines of the visual chart were achieved. The mean absolute errors (MAEs) between the prediction results and ground truth were 0.1482–0.2117 logMAR for 3-year predictions and 0.1198–0.1845 logMAR for 5-year predictions; the root mean square errors (RMSEs) were 0.1916–0.2942 logMAR for 3-year predictions and 0.1692–0.2537 logMAR for 5-year predictions. This is the first study to predict post-therapeutic BCVAs in young children. This work establishes a reliable method to predict prognosis 5 years in advance. The application of our research contributes to the design of visual intervention plans and visual prognosis.

The Developing Human Connectome Project: typical and disrupted perinatal functional connectivity

The Developing Human Connectome Project is an Open Science project that provides the first large sample of neonatal functional MRI data with high temporal and spatial resolution. These data enable mapping of intrinsic functional connectivity between spatially distributed brain regions under normal and adverse perinatal circumstances, offering a framework to study the ontogeny of large-scale brain organization in humans. Here, we characterize in unprecedented detail the maturation and integrity of resting state networks (RSNs) at term-equivalent age in 337 infants (including 65 born preterm). First, we applied group independent component analysis to define 11 RSNs in term-born infants scanned at 43.5–44.5 weeks postmenstrual age (PMA). Adult-like topography was observed in RSNs encompassing primary sensorimotor, visual and auditory cortices. Among six higher-order, association RSNs, analogues of the adult networks for language and ocular control were identified, but a complete default mode network precursor was not. Next, we regressed the subject-level datasets from an independent cohort of infants scanned at 37–43.5 weeks PMA against the group-level RSNs to test for the effects of age, sex and preterm birth. Brain mapping in term-born infants revealed areas of positive association with age across four of six association RSNs, indicating active maturation in functional connectivity from 37 to 43.5 weeks PMA. Female infants showed increased connectivity in inferotemporal regions of the visual association network. Preterm birth was associated with striking impairments of functional connectivity across all RSNs in a dose-dependent manner; conversely, connectivity of the superior parietal lobules within the lateral motor network was abnormally increased in preterm infants, suggesting a possible mechanism for specific difficulties such as developmental coordination disorder, which occur frequently in preterm children. Overall, we found a robust, modular, symmetrical functional brain organization at normal term age. A complete set of adult-equivalent primary RSNs is already instated, alongside emerging connectivity in immature association RSNs, consistent with a primary-to-higher order ontogenetic sequence of brain development. The early developmental disruption imposed by preterm birth is associated with extensive alterations in functional connectivity.

The emergence of a functionally flexible brain during early infancy

While adult brains are known to be functionally flexible, the emergence of a functionally flexible brain during early infancy is largely uncharted due the lack of approaches to assess neural flexibility in infants. Using recent advances of multilayer network approaches and a cohort of typically developing children who underwent longitudinal MRI during the first 2 y of life, we investigated the developmental characteristics of brain neural flexibility. The temporal and spatial emergence of a functionally flexible brain was revealed. Brain regions with high neural flexibility appear consistent with the core regions supporting cognitive flexibility processing in adults, whereas brain regions governing basic brain functions exhibit lower neural flexibility, demonstrating the emergence of functionally flexible brain during early infancy.

Adult brains are functionally flexible, a unique characteristic that is thought to contribute to cognitive flexibility. While tools to assess cognitive flexibility during early infancy are lacking, we aimed to assess the spatiotemporal developmental features of “neural flexibility” during the first 2 y of life. Fifty-two typically developing children 0 to 2 y old were longitudinally imaged up to seven times during natural sleep using resting-state functional MRI. Using a sliding window approach, MR-derived neural flexibility, a quantitative measure of the frequency at which brain regions change their allegiance from one functional module to another during a given time period, was used to evaluate the temporal emergence of neural flexibility during early infancy. Results showed that neural flexibility of whole brain, motor, and high-order brain functional networks/regions increased significantly with age, while visual regions exhibited a temporally stable pattern, suggesting spatially and temporally nonuniform developmental features of neural flexibility. Additionally, the neural flexibility of the primary visual network at 3 mo of age was significantly and negatively associated with cognitive ability evaluated at 5/6 y of age. The “flexible club,” comprising brain regions with neural flexibility significantly higher than whole-brain neural flexibility, were consistent with brain regions known to govern cognitive flexibility in adults and exhibited unique characteristics when compared to the functional hub and diverse club regions. Thus, MR-derived neural flexibility has the potential to reveal the underlying neural substrates for developing a cognitively flexible brain during early infancy.

Oculomotor deficits in children adopted from Eastern Europe

AIM

We aim to assess oculomotor behaviour in children adopted from Eastern Europe, who are at high risk of maternal alcohol consumption.

METHODS

This cross-sectional study included 29 adoptees and 29 age-matched controls. All of them underwent a complete ophthalmological examination. Oculomotor control, including fixation and saccadic performance, was assessed using a DIVE device, with eye tracking technology. Anthropometric and facial measurements were obtained from all the adopted children, to identify features of foetal alcohol spectrum disorders (FASD). Fixational and saccadic outcomes were compared between groups, and the effect of adoption and FASD features quantified.

RESULTS

Oculomotor performance was poorer in adopted children. They presented shorter (0.53 vs 1.43 milliseconds in the long task and 0.43 vs 0.82 in the short task) and more unstable fixations (with a bivariate contour ellipse area of 27.9 vs 11.6 degree² during the long task and 6.9 vs 1.3 degree² during the short task) and slower saccadic reactions (278 vs 197 milliseconds). Children with sentinel finding for FASD showed the worst oculomotor outcomes.

CONCLUSION

Children adopted from Eastern Europe present oculomotor deficits, affecting both fixation and saccadic skills. We highlight prenatal exposure to alcohol as the main cause for these deficits.

Use of complex visual stimuli allows controlled recruitment of cortical networks in infants

OBJECTIVE

To characterize cortical networks activated by patterned visual stimuli in infants, and to evaluate their potential for assessment of visual processing and their associations with neurocognitive development.

METHODS

Three visual stimuli, orientation reversal (OR), global form (GF), and global motion (GM), were presented to cohort of five-month-old infants (N = 26). Eye tracker was used to guide the stimulation and to choose epochs for analysis. Visual responses were recorded with electroencephalography and analysed in source space using weighted phase lag index as the connectivity measure. The networks were quantified using several metrics that were compared between stimuli and correlated to cognitive outcomes.

RESULTS

Responses to OR/GF/GM stimuli were observed in nearly all (96/100/100%) recordings. All stimuli recruited cortical networks that were partly condition-specific in their characteristics. The more complex GF and GM conditions recruited wider global networks than OR. Additionally, strength of the GF network showed positive association with later cognitive performance.

CONCLUSIONS

Network analysis suggests that visual stimulation recruits large-scale cortical networks that extend far beyond the conventional visual streams and that differ between stimulation conditions.

SIGNIFICANCE

The method allows controlled recruitment of wide cortical networks, which holds promise for the early assessment of visual processing and its related higher-order cognitive processes.

Neonatal White Matter Maturation Is Associated With Infant Language Development

BACKGROUND

While neonates have no sophisticated language skills, the neural basis for acquiring this function is assumed to already be present at birth. Receptive language is measurable by 6 months of age and meaningful speech production by 10-18 months of age. Fiber tracts supporting language processing include the corpus callosum (CC), which plays a key role in the hemispheric lateralization of language; the left arcuate fasciculus (AF), which is associated with syntactic processing; and the right AF, which plays a role in prosody and semantics. We examined if neonatal maturation of these fiber tracts is associated with receptive language development at 12 months of age.

METHODS

Diffusion-weighted imaging (DWI) was performed in 86 infants at 26.6 ± 12.2 days post-birth. Receptive language was assessed via the MacArthur-Bates Communicative Development Inventory at 12 months of age. Tract-based fractional anisotropy (FA) was determined using the NA-MIC atlas-based fiber analysis toolkit. Associations between neonatal regional FA, adjusted for gestational age at birth and age at scan, and language development at 12 months of age were tested using ANOVA models.

RESULTS

After multiple comparisons correction, higher neonatal FA was positively associated with receptive language at 12 months of age within the genu (p < 0.001), rostrum (p < 0.001), and tapetum (p < 0.001) of the CC and the left fronto-parietal AF (p = 0.008). No significant clusters were found in the right AF.

CONCLUSION

Microstructural development of the CC and the AF in the newborn is associated with receptive language at 12 months of age, demonstrating that interindividual variation in white matter microstructure is relevant for later language development, and indicating that the neural foundation for language processing is laid well ahead of the majority of language acquisition. This suggests that some origins of impaired language development may lie in the intrauterine and potentially neonatal period of life. Understanding how interindividual differences in neonatal brain maturity relate to the acquisition of function, particularly during early development when the brain is in an unparalleled window of plasticity, is key to identifying opportunities for harnessing neuroplasticity in health and disease.

Fast and accurate Slicewise OutLIer Detection (SOLID) with informed model estimation for diffusion MRI data

The accurate characterization of the diffusion process in tissue using diffusion MRI is greatly challenged by the presence of artefacts. Subject motion causes not only spatial misalignments between diffusion weighted images, but often also slicewise signal intensity errors. Voxelwise robust model estimation is commonly used to exclude intensity errors as outliers. Slicewise outliers, however, become distributed over multiple adjacent slices after image registration and transformation. This challenges outlier detection with voxelwise procedures due to partial volume effects. Detecting the outlier slices before any transformations are applied to diffusion weighted images is therefore required. In this work, we present i) an automated tool coined SOLID for slicewise outlier detection prior to geometrical image transformation, and ii) a framework to naturally interpret data uncertainty information from SOLID and include it as such in model estimators. SOLID uses a straightforward intensity metric, is independent of the choice of the diffusion MRI model, and can handle datasets with a few or irregularly distributed gradient directions. The SOLID-informed estimation framework prevents the need to completely reject diffusion weighted images or individual voxel measurements by downweighting measurements with their degree of uncertainty, thereby supporting convergence and well-conditioning of iterative estimation algorithms. In comprehensive simulation experiments, SOLID detects outliers with a high sensitivity and specificity, and can achieve higher or at least similar sensitivity and specificity compared to other tools that are based on more complex and time-consuming procedures for the scenarios investigated. SOLID was further validated on data from 54 neonatal subjects which were visually inspected for outlier slices with the interactive tool developed as part of this study, showing its potential to quickly highlight problematic volumes and slices in large population studies. The informed model estimation framework was evaluated both in simulations and in vivo human data.

Novel names extend for how long preschool children sample visual information

Known words can guide visual attention, affecting how information is sampled. How do novel words, those that do not provide any top-down information, affect preschoolers' visual sampling in a conceptual task? We proposed that novel names can also change visual sampling by influencing how long children look. We investigated this possibility by analyzing how children sample visual information when they hear a sentence with a novel name versus without a novel name. Children completed a match-to-sample task while their moment-to-moment eye movements were recorded using eye-tracking technology. Our analyses were designed to provide specific information on the properties of visual sampling that novel names may change. Overall, we found that novel words prolonged the duration of each sampling event but did not affect sampling allocation (which objects children looked at) or sampling organization (how children transitioned from one object to the next). These results demonstrate that novel words change one important dynamic property of gaze: Novel words can entrain the cognitive system toward longer periods of sustained attention early in development.

The emergence of autism spectrum disorder: insights gained from studies of brain and behaviour in high-risk infants

PURPOSE OF REVIEW

We review studies of infants at risk for autism spectrum disorder (ASD), proposing that the earliest manifestations of disrupted brain development can shed light on prebehavioural markers of risk and mechanisms underlying the heterogeneity of ASD.

RECENT FINDINGS

Prospective, longitudinal studies of infants at risk for ASD have revealed that behavioural signs of ASD are generally not observed until the second year of life. The developmental signs within the first year are often subtle and rooted in processes outside the core diagnostic domains of ASD, such as motor and visual perceptual function. However, studies examining early brain development and function have identified a myriad of atypicalities within the first year that are associated with risk for ASD.

SUMMARY

Longitudinal studies of high-risk infants provide a unique opportunity to identify and quantify the sources of the atypical development and developmental heterogeneity of ASD. Integration of assays of behaviour and brain in the first year of life, expansion of the definition of high risk, and coordinated efforts in multisite investigations to adequately power integrative studies will lead to new insights into mechanisms of atypical development and, ultimately, the ideal timing and target for interventions that aim to attenuate delays or impairments.

Oxiracetam can improve cognitive impairment after chronic cerebral hypoperfusion in rats

Chronic cerebral hypoperfusion (CCH) induces cognitive deficits. Although CCH can be improved, cognitive impairment is not improved accordingly. To date, many studies have focused on investigating the pathophysiological mechanisms of CCH; however, the treatment of the induced cognitive impairment remains ineffective. Thus, the mechanisms underlying cognitive impairment after CCH and potential agents for treating this impairment need to be explored further. Oxiracetam is a nootropic drug that improves clinical outcomes for some central nervous system (CNS) disorders. Whether it can improve cognitive impairment after CCH is unknown. In this study, we used behavioural methods, electrophysiology, biochemistry, histopathological staining and transmission electron microscope to investigate rat's cognitive impairment by CCH, and found that Oxiracetam could improve CCH-induced cognitive impairment and prevent deficits of neural plasticity, white matter lesions, and synaptic ultrastructure. These results suggest that Oxiracetam may be effective as a potential agent against CCH-induced cognitive impairment.

A novel measure of reliability in Diffusion Tensor Imaging after data rejections due to subject motion

Diffusion Tensor Imaging (DTI) is commonly challenged by subject motion during data acquisition, which often leads to corrupted image data. Currently used procedure in DTI analysis is to correct or completely reject such data before tensor estimations, however assessing the reliability and accuracy of the estimated tensor in such situations has evaded previous studies. This work aims to define the loss of data accuracy with increasing image rejections, and to define a robust method for assessing reliability of the result at voxel level. We carried out simulations of every possible sub-scheme (N=1,073,567,387) of Jones30 gradient scheme, followed by confirming the idea with MRI data from four newborn and three adult subjects. We assessed the relative error of the most commonly used tensor estimates for DTI and tractography studies, fractional anisotropy (FA) and the major orientation vector (V1), respectively. The error was estimated using two measures, the widely used electric potential (EP) criteria as well as the rotationally variant condition number (CN). Our results show that CN and EP are comparable in situations with very few rejections, but CN becomes clearly more sensitive to depicting errors when more gradient vectors and images were rejected. The error in FA and V1 was also found depend on the actual FA level in the given voxel; low actual FA levels were related to high relative errors in the FA and V1 estimates. Finally, the results were confirmed with clinical MRI data. This showed that the errors after rejections are, indeed, inhomogeneous across brain regions. The FA and V1 errors become progressively larger when moving from the thick white matter bundles towards more superficial subcortical structures. Our findings suggest that i) CN is a useful estimator of data reliability at voxel level, and ii) DTI preprocessing with data rejections leads to major challenges when assessing brain tissue with lower FA levels, such as all newborn brain, as well as the adult superficial, subcortical areas commonly traced in precise connectivity analyses between cortical regions.

Evidence for spared attention to faces in 7-month-old infants after prenatal exposure to antiepileptic drugs

INTRODUCTION

Prenatal antiepileptic drug (AED) exposure is associated with an increased risk of cognitive impairment and autism spectrum disorders detected mainly at the age of two to six years. We examined whether the developmental aberrations associated with prenatal AED exposure could be detected already in infancy and whether effects on visual attention can be observed at this early age.

MATERIAL AND METHODS

We compared a prospective cohort of infants with in utero exposure to AED (n=56) with infants without drug exposures (n=62). The assessments performed at the age of seven months included standardized neurodevelopmental scores (Griffiths Mental Developmental Scale and Hammersmith Infant Neurological Examination) as well as a novel eye-tracking-based test for visual attention and orienting to faces. Background information included prospective collection of AED exposure data, pregnancy outcome, neuropsychological evaluation of the mothers, and information on maternal epilepsy type.

RESULTS

Carbamazepine, oxcarbazepine, and valproate, but not lamotrigine or levetiracetam, were associated with impaired early language abilities at the age of seven months. The general speed of visuospatial orienting or attentional bias for faces measured by eye-tracker-based tests did not differ between AED-exposed and control infants.

DISCUSSION

Our findings support the idea that prenatal AED exposure may impair verbal abilities, and this effect may be detected already in infancy. In contrast, the early development of attention to faces was spared after in utero AED exposure.

Prediction of neuromotor outcome in infants born preterm at 11 years of age using volumetric neonatal magnetic resonance imaging and neurological examinations

AIM

To study the prognostic value of volumetric brain magnetic resonance imaging (MRI) at term equivalent age (TEA) and neurological examinations at TEA and at 2 years of corrected age for long-term neuromotor outcome in infants born very preterm.

METHOD

A total of 98 infants born very preterm were included. Structural and volumetric brain MRI and the Dubowitz neurologic examination were done at TEA. The Hammersmith Infant Neurological Examination (HINE) was performed at 2 years of corrected age. The Touwen examination was used for the assessment of minor neurological dysfunction (MND) at the age of 11 years.

RESULTS

Of all children (median birthweight 1083g [quartiles 820, 1300]; gestational age 28 5/7wks [26 4/7, 30 2/7]), 41 had simple MND, 11 had complex MND (cMND), and eight had cerebral palsy (CP). The negative and positive predictive value of structural brain MRI for cMND or CP was 88% and 50% respectively. Reduced volumes of total brain tissue, frontal lobes, basal ganglia and thalami, and cerebellum associated with cMND or CP. The results of the Dubowitz neurologic examination and the HINE correlated with the Touwen examination.

INTERPRETATION

Structural and volumetric MRI at TEA and structured neurological examinations predict long-term neuromotor outcome in infants born preterm.

Visual tracking in very preterm infants at 4 mo predicts neurodevelopment at 3 y of age

BACKGROUND

Typically developing infants track moving objects with eye and head movements in a smooth and predictive way at 4 mo of age, but this ability is delayed in very preterm infants. We hypothesized that visual tracking ability in very preterm infants predicts later neurodevelopment.

METHOD

In 67 very preterm infants (gestational age<32 wk), eye and head movements were assessed at 4 mo corrected age while the infant tracked a moving object. Gaze gain, smooth pursuit, head movements, and timing of gaze relative the object were analyzed off line. Results of the five subscales included in the Bayley Scales of Infant Development (BSID-III) at 3 y of age were evaluated in relation to the visual tracking data and to perinatal risk factors.

RESULTS

Significant correlations were obtained between gaze gain and cognition, receptive and expressive language, and fine motor function, respectively, also after controlling for gestational age, severe brain damage, retinopathy of prematurity, and bronchopulmonary dysplasia.

CONCLUSION

This is the first study demonstrating that the basic ability to visually track a moving object at 4 mo robustly predicts neurodevelopment at 3 y of age in children born very preterm.

Nystagmus in pediatric patients: interventions and patient-focused perspectives

Nystagmus refers to involuntary, typically conjugate, often rhythmic oscillations of the eyes. The most common cause of nystagmus in children is infantile nystagmus syndrome (INS). INS presents within the first few months of life and is sometimes accompanied by an ocular condition associated with sensory impairment. Because this condition affects a person throughout life, it is important to understand the options available to manage it. This review focuses on the underlying nystagmus etiology, psychosocial and functional effects of nystagmus, as well as current principles of management, including optical, pharmacological, surgical, and rehabilitative options. Currently, the neural mechanisms underlying INS are not fully understood. Treatment options are designed to increase foveation duration or correct anomalous head postures; however, evidence is limited to mainly pre- and post-study designs with few objective comparisons of treatment strategies. Management of INS should be individualized. The decision on which treatment is best suited for a particular patient lies with the patient and his/her physician.