Differential vulnerability of global motion, global form, and biological motion processing in full-term and preterm children

The relation of verbal and nonverbal skills to basic numerical processing of preterm versus term-born preschoolers

Verbal and nonverbal skills significantly contribute to individual differences in children's numerical development at the group level. However, less is known about whether the nature of the relations between verbal and nonverbal systems and numerical cognition varies depending on the unique characteristics children bring into numerical learning. To better delineate these associations, we examined the association between verbal and nonverbal skills and symbolic numerical development in preterm-born (PTB; n = 93; <37 weeks of gestation) children and term-born children (n = 104). We showed that PTB preschoolers, as a group, were at a higher risk of falling behind on certain numerical tasks (cardinality) but not on others (counting). There was, however, significant individual variability within the groups. Verbal and nonverbal skills contributed to the variability of children's numerical performance but did so differentially across the full spectrum of gestational age. Specifically, verbal skills moderated the association between gestational age and symbolic number performance (cardinality). The relation between verbal and cardinality skills was stronger at higher gestational ages compared with lower gestational ages. In addition, at higher gestational ages, children more frequently used retrieval strategy and less often relied solely on finger counting for the cardinality task. Shifting the focus from group differences to understanding individuals and their unique developmental pathways may enhance our insight into the risk and protective factors underlying the variability observed in all children.

Impairment in understanding grasping movements in egocentric and allocentric perspectives in children with cerebral palsy due to periventricular leukomalacia

Recognizing and understanding the actions of others through motion information are vital functions for social adaptation. Conditions like neurological disorders and motor impairments can impact sensitivity to biological motion, highlighting the intricate relationship between perceiving and executing movements. Our study centred on assessing the ability of children, encompassing both those with typical development and those diagnosed with cerebral palsy due to periventricular leukomalacia (PVL), to discriminate between depicted grasping of a small cylinder and a large cube. This discrimination task involved observing a point-light animation depicting an actor grasping the object, presented from either an allocentric perspective (observing others) or an egocentric viewpoint (observing oneself). Notably, children with PVL exhibited a pronounced and specific impairment in this task, irrespective of the viewpoint, as evidenced by thresholds increasing by nearly a factor of two. When comparing this impairment to difficulties in form or motion perception, we identified a robust correlation between egocentric biological motion and form sensitivity. However, there was no similar correlation between motion and biological motion sensitivity, suggesting a deficit in the visual system rather than the visuo-motor control system. These findings contribute to our understanding of the intricate interplay between motor and visual processing in individuals with congenital brain lesions, shedding light on the significant involvement of the visual system in cases of PVL.

Visuospatial Perception in Prematurely Born Children Without Cerebral Palsy or Retinopathy but With Scholar Complaints

In the absence of any complaints in early childhood, preterm children remain more at risk of encountering academic difficulties, but their clinical picture remains not well characterized. We screened visuospatial perception in 70 children born preterm consulting for scholar complaints. Developmental Coordination Disorder (with or without comorbidities) was associated with high prevalence (27%) of impaired perception of spatial relationship. Prematurely born children who obtained no diagnosis of Neuro-Developmental Disorder exhibited a high prevalence (31%) of impaired perception of object magnitude. Regression revealed that low gestational age and fetal growth restriction significantly predicted the magnitude but not the spatial relationship perception.

Lipid analysis of breast milk and formula for preterm infants and the application and prospects of novel structural lipids - a comprehensive review

Preterm infants, often characterized by lower birth weights and underdeveloped physiologies, necessitate specialized nutritional care. While breast milk stands as the ideal nutritional source, offering substantial energy through its fatty acid content to support the infants' growth and developmental needs, its usage might not always be feasible. Fatty acids in breast milk are critical for the development of these infants. In scenarios where breast milk is not an option, formula feeding becomes a necessary alternative. Thus, a comprehensive understanding of the fatty acid profiles in both breast milk and formulas is crucial for addressing the distinct nutritional requirements of preterm infants. This paper aims to summarize the effects of lipid composition, structure, and positioning in breast milk and formula on the growth and development of preterm infants. Furthermore, it explores recent advancements in the use of novel structural lipids in formulas, laying the groundwork for future innovations in formula design specifically catered to the needs of preterm infants.

Prematurity May Affect the Postoperative Sensory Results in Children With Strabismus

PURPOSE

To analyze the motor and sensory outcomes of strabismus surgery in children born preterm (premature group) and full-term (control group).

METHODS

The study was performed at a tertiary university hospital. Children who underwent strabismus surgery between 2012 and 2019 were retrospectively reviewed. The success of surgery, postoperative over-correction and undercorrection rates, and stereopsis and fusion test results were compared between the premature and control groups.

RESULTS

There were 70 patients in the premature group (mean gestational age: 31.25 weeks; range: 24 to 35 weeks) and 242 patients in the control group. The amounts of preoperative and postoperative deviations and overcorrection, undercorrection, and success rates were similar between the premature and control groups (P > .05). Stereopsis improved from 560 to 300 arc/sec postoperatively in the premature group (P = .066) and from 1,156 to 685 arc/sec in the control group (P < .001). The rate of fusion increased from 12.5% to 25% in the premature group (P = .50) and from 17% to 47% in the control group (P < .001). The analysis of strabismus subgroups revealed significant improvement of fusion in full-term patients (P < .001) and not in preterm patients (P = .50) with esotropia. Preoperative amount of deviation was the only risk factor for surgical success (P < .001). Age, sex, history of prematurity, and spherical equivalent refraction were not correlated with undercorrection (P > .05).

CONCLUSIONS

Regardless of the type of strabismus, although the functional results after strabismus surgery were similar in preterm and full-term patients, the gain of stereopsis and central fusion was significantly higher in full-term patients compared to preterm patients. [J Pediatr Ophthalmol Strabismus. 2024;61(4):267-272.].

Associations between neonatal nutrition and visual outcomes in 7-year-old children born very preterm

PURPOSE

There is uncertainty about the effect of increased neonatal protein intake on neurodevelopmental outcomes following preterm birth. The aim of this study was to assess the effect of a change in neonatal nutrition protocol at a major tertiary neonatal intensive care unit intended to increase protein intake on ophthalmic and visual development in school-age children born very preterm.

METHODS

The study cohort comprised children (n = 128) with birthweight <1500 g or gestational age < 30 weeks born at Auckland City Hospital before (OldPro group, n = 55) and after (NewPro group, n = 73) a reformulation of parenteral nutrition that resulted in increased total protein intake during the first postnatal week and decreased carbohydrate, total parenteral fluid and sodium intake. Clinical and psychophysical vision assessments were completed at 7 years' corrected age, including visual acuity, global motion perception (a measure of dorsal stream function), stereoacuity, ocular motility and ocular health. Composite measures of favourable overall visual, binocular and functional visual outcomes along with individual vision measures were compared between the groups using logistic and linear regression models.

RESULTS

Favourable overall visual outcome did not differ between the two groups. However, global motion perception was better in the NewPro group (p = 0.04), whereas the OldPro group were more likely to have favourable binocular visual outcomes (60% vs. 36%, p = 0.02) and passing stereoacuity (p = 0.02).

CONCLUSIONS

These results indicate subtle but complex associations between early neonatal nutrition after very preterm birth and visual development at school age.

Assessing Higher-Order Visual Processing in Cerebral Visual Impairment Using Naturalistic Virtual-Reality-Based Visual Search Tasks

Cerebral visual impairment (CVI) is a brain-based disorder associated with the maldevelopment of central visual pathways. Individuals with CVI often report difficulties with daily visual search tasks such as finding a favorite toy or familiar person in cluttered and crowded scenes. We developed two novel virtual reality (VR)-based visual search tasks combined with eye tracking to objectively assess higher order processing abilities in CVI. The first (virtual toybox) simulates a static object search, while the second (virtual hallway) represents a dynamic human search task. Participants were instructed to search for a preselected target while task demand was manipulated with respect to the presence of surrounding distractors. We found that CVI participants (when compared to age-matched controls) showed an overall impairment with visual search on both tasks and with respect to all gaze metrics. Furthermore, CVI participants showed a trend of worsening performance with increasing task demand. Finally, search performance was also impaired in CVI participants with normal/near normal visual acuity, suggesting that reduced stimulus visibility alone does not account for these observations. This novel approach may have important clinical utility in helping to assess environmental factors related to functional visual processing difficulties observed in CVI.

Developmental changes in gaze patterns in response to radial optic flow in toddlerhood and childhood

A large field visual motion pattern (optic flow) with a radial pattern provides a compelling perception of self-motion; a radially expanding/contracting optic flow generates the perception of forward/backward locomotion. Moreover, the focus of a radial optic flow, particularly an expansive flow, is an important visual cue to perceive and control the heading direction during human locomotion. Previous research has shown that human gaze patterns have an “expansion bias”: a tendency to be more attracted to the focus of expansive flow than to the focus of contractive flow. We investigated the development of the expansion bias in children (N = 240, 1–12 years) and adults (N = 20). Most children aged ≥ 5 years and adults showed a significant tendency to shift their gaze to the focus of an expansive flow, whereas the youngest group (1-year-old children) showed a significant but opposing tendency; their gaze was more attracted to the focus of contractive flow than to the focus of expansive flow. The relationship between the developmental change from the “contraction bias” in early toddlerhood to the expansion bias in the later developmental stages and possible factors (e.g., global visual motion processing abilities and locomotor experiences) are discussed.

Multimodal classification of extremely preterm and term adolescents using the fusiform gyrus: A machine learning approach

OBJECTIVE

Extremely preterm birth has been associated with atypical visual and neural processing of faces, as well as differences in gray matter structure in visual processing areas relative to full-term peers. In particular, the right fusiform gyrus, a core visual area involved in face processing, has been shown to have structural and functional differences between preterm and full-term individuals from childhood through early adulthood. The current study used multiple neuroimaging modalities to build a machine learning model based on the right fusiform gyrus to classify extremely preterm birth status.

METHOD

Extremely preterm adolescents (n = 20) and full-term peers (n = 24) underwent structural and functional magnetic resonance imaging. Group differences in gray matter density, measured via voxel-based morphometry (VBM), and blood-oxygen level-dependent (BOLD) response to face stimuli were explored within the right fusiform. Using group difference clusters as seed regions, analyses investigating outgoing white matter streamlines, regional homogeneity, and functional connectivity during a face processing task and at rest were conducted. A data driven approach was utilized to determine the most discriminative combination of these features within a linear support vector machine classifier.

RESULTS

Group differences in two partially overlapping clusters emerged: one from the VBM analysis showing less density in the extremely preterm cohort and one from BOLD response to faces showing greater activation in the extremely preterm relative to full-term youth. A classifier fit to the data from the cluster identified in the BOLD analysis achieved an accuracy score of 88.64% when BOLD, gray matter density, regional homogeneity, and functional connectivity during the task and at rest were included. A classifier fit to the data from the cluster identified in the VBM analysis achieved an accuracy score of 95.45% when only BOLD, gray matter density, and regional homogeneity were included.

CONCLUSION

Consistent with previous findings, we observed neural differences in extremely preterm youth in an area that plays an important role in face processing. Multimodal analyses revealed differences in structure, function, and connectivity that, when taken together, accurately distinguish extremely preterm from full-term born youth. Our findings suggest a compensatory role of the fusiform where less dense gray matter is countered by increased local BOLD signal. Importantly, sub-threshold differences in many modalities within the same region were informative when distinguishing between extremely preterm and full-term youth.

Brain microstructural antecedents of visual difficulties in infants born very preterm

Infants born very preterm (VPT) are at risk of later visual problems. Although neonatal screening can identify ophthalmologic abnormalities, subtle perinatal brain injury and/or delayed brain maturation may be significant contributors to complex visual-behavioral problems. Our aim was to assess the micro and macrostructural antecedents of early visual-behavioral difficulties in VPT infants by using diffusion MRI (dMRI) at term-equivalent age. We prospectively recruited a cohort of 262 VPT infants (≤32 weeks gestational age [GA]) from five neonatal intensive care units. We obtained structural and diffusion MRI at term-equivalent age and administered the Preverbal Visual Assessment (PreViAs) questionnaire to parents at 3-4 months corrected age. We used constrained spherical deconvolution to reconstruct nine white matter tracts of the visual pathways with high reliability and performed fixel-based analysis to derive fiber density (FD), fiber-bundle cross-section (FC), and combined fiber density and cross-section (FDC). In multiple logistic regression analyses, we related these tract metrics to visual-behavioral function. Of 262 infants, 191 had both high-quality dMRI and completed PreViAs, constituting the final cohort: mean (SD) GA was 29.3 (2.4) weeks, 90 (47.1%) were males, and postmenstrual age (PMA) at MRI was 42.8 (1.3) weeks. FD and FC of several tracts were altered in infants with (N = 59) versus those without retinopathy of prematurity (N = 132). FDC of the left posterior thalamic radiations (PTR), left inferior longitudinal fasciculus (ILF), right superior longitudinal fasciculus (SLF), and left inferior fronto-occipital fasciculus (IFOF) were significantly associated with visual attention scores, prior to adjusting for confounders. After adjustment for PMA at MRI, GA, severe retinopathy of prematurity, and total brain volume, FDC of the left PTR, left ILF, and left IFOF remained significantly associated with visual attention. Early visual-behavioral difficulties in VPT infants are preceded by micro and macrostructural abnormalities in several major visual pathways at term-equivalent age.

Longitudinal study of infants receiving extra motor stimulation, full‐term control infants, and infants born preterm: High‐density EEG analyses of cortical activity in response to visual motion

Electroencephalography was used to investigate the effects of extrastimulation and preterm birth on the development of visual motion perception during early infancy. Infants receiving extra motor stimulation in the form of baby swimming, a traditionally raised control group, and preterm born infants were presented with an optic flow pattern simulating forward and reversed self‐motion and unstructured random visual motion before and after they achieved self‐produced locomotion. Extrastimulated infants started crawling earlier and displayed significantly shorter N2 latencies in response to visual motion than their full‐term and preterm peers. Preterm infants could not differentiate between visual motion conditions, nor did they significantly decrease their latencies with age and locomotor experience. Differences in induced activities were also observed with desynchronized theta‐band activity in all infants, but with more mature synchronized alpha–beta band activity only in extrastimulated infants after they had become mobile. Compared with the other infants, preterm infants showed more widespread desynchronized oscillatory activities at lower frequencies at the age of 1 year (corrected for prematurity). The overall advanced performance of extrastimulated infants was attributed to their enriched motor stimulation. The poorer responses in the preterm infants could be related to impairment of the dorsal visual stream that is specialized in the processing of visual motion.

Neurobehavioral Phenotype and Dysexecutive Syndrome of Preterm Children: Comorbidity or Trigger? An Update

Premature birth is a worldwide public health priority. One in ten children is born before 37 weeks of gestational age and, in developed countries, survival rates without major neonatal morbidity are increasing. Although severe sequelae associated with these births have decreased, their neurobehavioral difficulties, often associated in multiple fields, remain stable but still widespread. These neurobehavioral difficulties hamper the normal development of academic achievements and societal integration and intensify the children's needs for rehabilitation during their preschool and academic years. Severe sequelae increase when gestational age decreases. This is even truer if the socio-cultural background is impeded by low income, education and language skills as compared with defined averages. However, moderate and/or minor neurocognitive and/or behavioral difficulties are almost identical for a moderate or a late preterm birth. Obtaining a better clinical description of neurobehavioral characteristics of those pretermly born, once they reach preschool age, is essential to detect behavioral issues as well as early specific cognitive difficulties (working memory, planning, inhibition, language expression and reception, attention and fine motor skills, etc.). Such information would provide a better understanding of the executive functions' role in brain connectivity, neurodevelopment and neuroanatomical correlation with premature encephalopathy.

Neural correlates associated with impaired global motion perception in cerebral visual impairment (CVI)

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Cerebral visual impairment (CVI) is associated with impaired global motion processing.

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Mean motion coherence thresholds was higher in individuals with CVI.

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fMRI responses in area hMT+ showed an aberrant response profile in CVI.

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White matter tract reconstruction revealed cortico-cortical dysmyelination in CVI.

Cerebral visual impairment (CVI) is associated with a wide range of visual perceptual deficits including global motion processing. However, the underlying neurophysiological basis for these impairments remain poorly understood. We investigated global motion processing abilities in individuals with CVI compared to neurotypical controls using a combined behavioral and multi-modal neuroimaging approach. We found that CVI participants had a significantly higher mean motion coherence threshold (determined using a random dot kinematogram pattern simulating optic flow motion) compared to controls. Using functional magnetic resonance imaging (fMRI), we investigated activation response profiles in functionally defined early (i.e. primary visual cortex; area V1) and higher order (i.e. middle temporal cortex; area hMT+) stages of motion processing. In area V1, responses to increasing motion coherence were similar in both groups. However, in the CVI group, activation in area hMT+ was significantly reduced compared to controls, and consistent with a surround facilitation (rather than suppression) response profile. White matter tract reconstruction obtained from high angular resolution diffusion imaging (HARDI) revealed evidence of increased mean, axial, and radial diffusivities within cortico-cortical (i.e. V1-hMT+), but not thalamo-hMT+ connections. Overall, our results suggest that global motion processing deficits in CVI may be associated with impaired signal integration and segregation mechanisms, as well as white matter integrity at the level of area hMT+.

Reduced 2D form coherence and 3D structure from motion sensitivity in developmental dyscalculia

Developmental dyscalculia (DD) is a specific learning disability affecting the development of numerical and arithmetical skills. The origin of DD is typically attributed to the suboptimal functioning of key regions within the dorsal visual stream (parietal cortex) which support numerical cognition. While DD individuals are often impaired in visual numerosity perception, the extent to which they also show a wider range of visual dysfunctions is poorly documented. In the current study we measured sensitivity to global motion (translational and flow), 2D static form (Glass patterns) and 3D structure from motion in adults with DD and control subjects. While sensitivity to global motion was comparable across groups, thresholds for static form and structure from motion were higher in the DD compared to the control group, irrespective of associated reading impairments. Glass pattern sensitivity predicted numerical abilities, and this relation could not be explained by recently reported differences in visual crowding. Since global form sensitivity has often been considered an index of ventral stream function, our findings could indicate a cortical dysfunction extending beyond the dorsal visual stream. Alternatively, they would fit with a role of parietal cortex in form perception under challenging conditions requiring multiple element integration.

Visuopathy of prematurity: is retinopathy just the tip of the iceberg?

Research on retinopathy of prematurity (ROP) focuses mainly on the abnormal vascularization patterns that are directly visible for ophthalmologists. However, recent findings indicate that children born prematurely also exhibit changes in the retinal cellular architecture and along the dorsal visual stream, such as structural changes between and within cortical areas. Moreover, perinatal sustained systemic inflammation (SSI) is associated with an increased risk for ROP and the visual deficits that follow. In this paper, we propose that ROP might just be the tip of an iceberg we call visuopathy of prematurity (VOP). The VOP paradigm comprises abnormal vascularization of the retina, alterations in retinal cellular architecture, choroidal degeneration, and abnormalities in the visual pathway, including cortical areas. Furthermore, VOP itself might influence the developmental trajectories of cerebral structures and functions deemed responsible for visual processing, thereby explaining visual deficits among children born preterm.

Dorsal and Ventral Stream Function in Children With Developmental Coordination Disorder

Dorsal stream cortical networks underpin a cluster of visuomotor, visuospatial, and visual attention functions. Sensitivity to global coherence of motion and static form is considered a signature of visual cortical processing in the dorsal stream (motion) relative to the ventral stream (form). Poorer sensitivity to global motion compared to global static form has been found across a diverse range of neurodevelopmental disorders, suggesting a “dorsal stream vulnerability.” However, previous studies of global coherence sensitivity in Developmental Coordination Disorder (DCD) have shown conflicting findings. We examined two groups totalling 102 children with DCD (age 5–12 years), using the “Ball in the Grass” psychophysical test to compare sensitivity to global motion and global static form. Motor impairment was measured using the Movement-ABC (M-ABC). Global coherence sensitivity was compared with a typically developing control group (N = 69) in the same age range. Children with DCD showed impaired sensitivity to global motion (p = 0.002), but not global form (p = 0.695), compared to controls. Within the DCD group, motor impairment showed a significant linear relationship with global form sensitivity (p < 0.001). There was also a significant quadratic relationship between motor impairment and global motion sensitivity (p = 0.046), where poorer global motion sensitivity was only apparent with greater motor impairment. We suggest that two distinct visually related components, associated with global form and global motion sensitivity, contribute to DCD differentially over the range of severity of the disorder. Possible neural circuitry underlying these relationships is discussed.

Cognitive and academic outcomes of children born extremely preterm

Extremely preterm birth is associated with increased risk for a spectrum of neurodevelopmental problems. This review describes the nature of cognitive and academic outcomes of extremely preterm survivors across childhood and adolescence. Evidence across meta-analyses and large prospective birth cohorts indicate that early developmental difficulties in children born extremely preterm do not resolve with age and are not improving over time despite advancements in neonatal care. While extremely preterm birth confers increased risk of widespread cognitive difficulties, considerable heterogeneity in outcomes is evident across individuals. There is a continued need for high-quality longitudinal studies to understand the developmental progression of cognitive and academic skills following extremely preterm birth, and greater focus on understanding contributing factors that may help to explain the individual variability in cognitive and academic outcomes of extremely preterm survivors.

Social cognition in individuals born preterm

Faces hold a substantial value for effective social interactions and sharing. Covering faces with masks, due to COVID-19 regulations, may lead to difficulties in using social signals, in particular, in individuals with neurodevelopmental conditions. Daily-life social participation of individuals who were born preterm is of immense importance for their quality of life. Here we examined face tuning in individuals (aged 12.79 ± 1.89 years) who were born preterm and exhibited signs of periventricular leukomalacia (PVL), a dominant form of brain injury in preterm birth survivors. For assessing the face sensitivity in this population, we implemented a recently developed experimental tool, a set of Face-n-Food images bordering on the style of Giuseppe Arcimboldo. The key benefit of these images is that single components do not trigger face processing. Although a coarse face schema is thought to be hardwired in the brain, former preterms exhibit substantial shortages in the face tuning not only compared with typically developing controls but also with individuals with autistic spectrum disorders. The lack of correlations between the face sensitivity and other cognitive abilities indicates that these deficits are domain-specific. This underscores impact of preterm birth sequelae for social functioning at large. Comparison of the findings with data in individuals with other neurodevelopmental and neuropsychiatric conditions provides novel insights into the origins of deficient face processing.

Typical Crossmodal Numerosity Perception in Preterm Newborns

Premature birth is associated with a high risk of damage in the parietal cortex, a key area for numerical and non-numerical magnitude perception and mathematical reasoning. Children born preterm have higher rates of learning difficulties for school mathematics. In this study, we investigated how preterm newborns (born at 28-34 weeks of gestation age) and full-term newborns respond to visual numerosity after habituation to auditory stimuli of different numerosities. The results show that the two groups have a similar preferential looking response to visual numerosity, both preferring the incongruent set after crossmodal habituation. These results suggest that the numerosity system is resistant to prematurity.

Motion perception and its disorders

As we live in a dynamic world, motion is a fundamental aspect of our visual experience. The advent of computerized stimuli has allowed controlled study of a wide array of motion phenomena, including global integration and segmentation, speed and direction discrimination, motion aftereffects, the optic flow that accompanies self-motion, perception of object form derived from motion cues, and point-light biological motion. Animal studies first revealed the existence of a motion-selective region, the middle temporal (MT) area, also known as V5, located in the lateral occipitotemporal cortex, followed by areas such as V5A (also known as MST, the middle superior temporal area), V6/V6A, the ventral intraparietal area, and others. In humans there are rare cases of bilateral lesions of the V5/V5A complex causing cerebral akinetopsia, a severe impairment of motion perception. Unilateral V5/V5A lesions are more common but cause milder asymptomatic deficits, often limited to the contralateral hemifield, while parietal lesions can impair perception of point-light biological motion or high-level motion tasks that are attentionally demanding. Impairments of motion perception have also been described in optic neuropathy, particularly glaucoma, as well as Alzheimer's disease, Parkinson's disease with dementia, and dementia with Lewy body disease. Prematurity with or without periventricular leukomalacia and developmental syndromes such as Williams' syndrome, autism, and dyslexia have also been associated with impaired motion perception, suggesting a developmental vulnerability of the dorsal pathway.

The forest, the trees, and the leaves in preterm children: the impact of prematurity on a visual search task containing three-level hierarchical stimuli

Very preterm (VPT; < 33 gestational weeks) children are at risk of developing visuospatial deficits, including local/global attention deficits. They are also more likely to develop poorer inhibitory control. Here, we investigated, using the same stimuli, the potential local/global attention and inhibitory control deficits of VPT children using three levels compound stimuli (global, intermediate, and local levels), more ecological than the ones used in a classic global/local task (Navon task). We compared the results from 22 VPT children to those of a control group of 21 children to investigate (1) how VPT children processed compound stimuli with three-level information and (2) how inhibitory control in a visual task differs between VPT and control children. The results revealed that VPT children had no difficulty processing information presented at the local level. By contrast, VPT children were impaired when considering the intermediate and global levels of processing in comparison to control children. Finally, a reduced efficiency in VPT children in inhibiting visual distractors was evidenced for the conditions with a larger number of distractors. These results are discussed in terms of neurodevelopmental disorders of both dorsal stream (global visual processing) and prefrontal regions (inhibitory control) in VPT children. Given the central role of visuospatial and inhibitory control in day-to-day situations, the present results provide important clues for pedagogical implications regarding the organization of visual information presented to VPT children.

Cortical thickness of primary visual cortex correlates with motion deficits in periventricular leukomalacia

Impairments of visual motion perception and, in particular, of flow motion have been consistently observed in premature and very low birth weight subjects during infancy. Flow motion information is analyzed at various cortical levels along the dorsal pathways, with information mainly provided by primary and early visual cortex (V1, V2 and V3). We investigated the cortical stage of the visual processing that underlies these motion impairments, measuring Grey Matter Volume and Cortical Thickness in 13 children with Periventricular Leukomalacia (PVL). The cortical thickness, but not the grey matter volume of area V1, correlates negatively with motion coherence sensitivity, indicating that the thinner the cortex, the better the performance among the patients. However, we did not find any such association with either the thickness or volume of area MT, MST and areas of the IPS, suggesting damage at the level of primary visual cortex or along the optic radiation.

Investigating the Interaction Between Form and Motion Processing: A Review of Basic Research and Clinical Evidence

A widely held view of the visual system supported the perspective that the primate brain is organized in two main specialized streams, called the ventral and dorsal streams. The ventral stream is known to be involved in object recognition (e.g., form and orientation). In contrast, the dorsal stream is thought to be more involved in spatial recognition (e.g., the spatial relationship between objects and motion direction). Recent evidence suggests that these two streams are not segregated but interact with each other. A class of visual stimuli known as Glass patterns has been developed to shed light on this process. Glass patterns are visual stimuli made of pairs of dots, called dipoles, that give the percept of a specific form or apparent motion, depending on the spatial and temporal arrangement of the dipoles. In this review, we show an update of the neurophysiological, brain imaging, psychophysical, clinical, and brain stimulation studies which have assessed form and motion integration mechanisms, and the level at which this occurs in the human and non-human primate brain. We also discuss several studies based on non-invasive brain stimulation techniques that used different types of visual stimuli to assess the cortico-cortical interactions in the visual cortex for the processing of form and motion information. Additionally, we discuss the timing of specific visual processing in the ventral and dorsal streams. Finally, we report some parallels between healthy participants and neurologically impaired patients in the conscious processing of form and motion.

Premature birth affects visual body representation and body schema in preterm children

Research has demonstrated that from the first six months of life infants show early sensitivity to body visual features and rely on sensorimotor and proprioceptive inputs in forming representations of their own bodies. Premature birth interferes with typical exposition to visual, sensorimotor and proprioceptive stimulation, thus presumably affecting the development of body representations. Here, we tested this hypothesis by comparing the performance of preterm children with that of age-matched full-termchildren in two tasks assessing, respectively, visual body processing and body schema. We found that preterm children had spared configural processing but altered holistic processing of others' bodies and showed a general difficulty in expressing visuospatial judgements on body stimuli. Furthermore, body-centered visuospatial abilities were associated with specific impairments in operating object-based visuospatial transformations. The findings of this study indicate that preterm birth might interfere with the development of body representations at the levels of body visual perceptual processing and of body schema, with effects even on visuo-spatial abilities for non-bodily stimuli. Body-centered rehabilitative interventions should be proposed to preterm children in order to enhance visuo-spatial abilities and higher-level cognitive functions.

Flash VEP in clinically stable pre-term and full-term infants

PURPOSE

Pre-term infants are at risk of abnormal visual development that can range from subtle to severe. The aim of this study was to compare flash VEPs in clinically stable pre-term and full-term infants at 6 months of age.

METHODS

Twenty-five pre-term and 25 full-term infants underwent flash VEP testing at the age of 6 months. Monocular VEPs were recorded using flash goggles on a RETIscan system under normal sleeping conditions. Amplitude and peak time responses of the P2 component in the two eyes were averaged and compared between the two groups. Multiple regression analyses were performed to assess the relationship of the P2 responses with birth weight (BW) and gestational age (GA).

RESULTS

At 6 months corrected age, pre-term infants had significantly delayed P2 peak times than full-term infants (mean difference: 10.88 [95% CI 4.00-17.76] ms, p = 0.005). Pre-term infants also showed significantly reduced P2 amplitudes as compared to full-term infants (mean difference: 2.36 [0.83-3.89] µV, p = 0.003). Although the regression model with GA and BW as fixed factors explained 20% of the variance in the P2 peak time (F_2,47 = 5.98, p = .0045), only GA showed a significant negative relationship (β = -2.66, p = .003). Neither GA (β = 0.21, p = .28) nor BW (β = 0.001, p = .32) showed any relationship with P2 amplitude.

CONCLUSIONS

Our results demonstrate that, compared with full-term infants, clinically stable pre-term infants exhibit abnormal flash VEPs, with a delay in P2 peak time and a reduction in P2 amplitude. These findings support a potential dysfunction of the visual pathway in clinically stable pre-term infants as compared to full-term infants.

Visual development

The developing visual brain is an integrated system, linking analysis of the visual input to visuomotor control, visual cognition, and attention. Major points in human visual development are the presence of rudimentary pathways present at birth which can control fixation behavior, with subsequent development of specific functions. These functions include the emergence of cortical selectivity; the integration of local signals to provide global representations of motion, shape, and space; the development of visuomotor modules for eye movements, manual reaching, and locomotion; and the development of distinct attentional systems. Measures of these processes in infancy and early childhood can provide indicators of broader brain development in the at-risk child. A key system in development is the dorsal cortical stream. Measures of global motion processing, visuomotor actions, and attention suggest that this system is particularly vulnerable in children with a wide range of neurodevelopmental disorders. Early disorders of the eye (strabismus, cataract) reveal the level of plasticity in the developing visual system and the ways in which early experience can affect the course of functional development.

Neuroplasticity in cerebral visual impairment (CVI): Assessing functional vision and the neurophysiological correlates of dorsal stream dysfunction

Cerebral visual impairment (CVI) results from perinatal injury to visual processing structures and pathways and is the most common individual cause of pediatric visual impairment and blindness in developed countries. While there is mounting evidence demonstrating extensive neuroplastic reorganization in early onset, profound ocular blindness, how the brain reorganizes in the setting of congenital damage to cerebral (i.e. retro-geniculate) visual pathways remains comparatively poorly understood. Individuals with CVI exhibit a wide range of visual deficits and, in particular, present with impairments of higher order visual spatial processing (referred to as "dorsal stream dysfunction") as well as object recognition (associated with processing along the ventral stream). In this review, we discuss the need for ongoing work to develop novel, neuroscience-inspired approaches to investigate functional visual deficits in this population. We also outline the role played by advanced structural and functional neuroimaging in helping to elucidate the underlying neurophysiology of CVI, and highlight key differences with regard to patterns of neural reorganization previously described in ocular blindness.

Visual configural processing in adults born at extremely low birth weight

Being born at extremely low birth weight (ELBW; ≤1,000 g) is associated with enduring visual impairments. We tested for long-term, higher order visual processing problems in the oldest known prospectively followed cohort of ELBW survivors. Configural processing (spacing among features of an object) was examined in 62 adults born at ELBW (M_age  = 31.9 years) and 82 adults born at normal birth weight (NBW; ≥2,500 g: M_age  = 32.5 years). Pairs of human faces, monkey faces, or houses were presented in a delayed match-to-sample task, where non-matching stimuli differed only in the spacing of their features. Discrimination accuracy for each stimulus type was compared between birth weight groups, adjusting for neurosensory impairment, visual acuity, binocular fusion ability, IQ, and sex. Both groups were better able to discriminate human faces than monkey faces (p < .001). However, the ELBW group discriminated between human faces (p < .001), between monkey faces (p < .001), and to some degree, between houses (p < .06), more poorly than NBW control participants, suggesting a general deficit in perceptual processing. Human face discrimination was related to performance IQ (PIQ) across groups, but especially among ELBW survivors. Coding (a PIQ subtest) also predicted human face discrimination in ELBW survivors, consistent with previously reported links between visuo-perceptive difficulties and regional slowing of cortical activity in individuals born preterm. Correlations with Coding suggested ELBW survivors may have used a feature-matching approach to processing human faces. Future studies could examine brain-based anatomical and functional evidence for altered face processing, as well as the social and memory consequences of face-processing deficits in ELBW survivors.

Morbidity in ≤1500-Gram Births in Spain, 1993-2011: Study of a Sample of 1200 Cases

Background and Objective. Preterm birth has a major impact on growth, and very preterm birth is associated with disabilities in numerous developmental domains. This article describes and quantifies morbidities in a sample of 1200 ≤1500-g births in Spain between 1993 and 2011 based on parent information, and it highlights several variables that influence these morbidities. Methods. Multiple method surveys using computer-assisted telephones interviewing and computer-assisted web interviewing methods. Sample design was intentional. Most subjects were contacted via their referral hospitals. Data collection was done from April 2013 to June 2014. Prior to the survey, extensive qualitative fieldwork was conducted, including nonparticipant observation in neonatal units and the design and analysis of discussion groups and interviews with professionals and families, including preterm adolescents. Results. A total of 44.2% of the sample were experiencing morbidity (mean: 1.788 morbidities per child). The most prevalent types were learning difficulties (34.4%) and attention deficit/hyperactivity disorder (31.5%). The most influential variables were male gender, age, lower birthweight, private hospital admission for birth, scarcity of health resources in the family's residential area, non-Spanish maternal birthplace, and emotional distress in the primary carer. Conclusions. Overall, the total percentage of very low birth weight children with morbidities has decreased moderately between 1993 and 2011, thanks to major socio-sanitary improvements during this period. Biological and medical variables, rather than family factors, explain more accurately the presence of morbidities in children with birth weight ≤1500 g.

New insights into the role of motion and form vision in neurodevelopmental disorders

A selective deficit in processing the global (overall) motion, but not form, of spatially extensive objects in the visual scene is frequently associated with several neurodevelopmental disorders, including preterm birth. Existing theories that proposed to explain the origin of this visual impairment are, however, challenged by recent research. In this review, we explore alternative hypotheses for why deficits in the processing of global motion, relative to global form, might arise. We describe recent evidence that has utilised novel tasks of global motion and global form to elucidate the underlying nature of the visual deficit reported in different neurodevelopmental disorders. We also examine the role of IQ and how the sex of an individual can influence performance on these tasks, as these are factors that are associated with performance on global motion tasks, but have not been systematically controlled for in previous studies exploring visual processing in clinical populations. Finally, we suggest that a new theoretical framework is needed for visual processing in neurodevelopmental disorders and present recommendations for future research.

The effects of preterm birth on visual development

Children born very preterm are at a greater risk of abnormal visual and neurological development when compared to children born at full term. Preterm birth is associated with retinopathy of prematurity (a proliferative retinal vascular disease) and can also affect the development of brain structures associated with post-retinal processing of visual information. Visual deficits common in children born preterm, such as reduced visual acuity, strabismus, abnormal stereopsis and refractive error, are likely to be detected through childhood vision screening programs, ophthalmological follow-up or optometric care. However, routine screening may not detect other vision problems, such as reduced visual fields, impaired contrast sensitivity and deficits in cortical visual processing, that may occur in children born preterm. For example, visual functions associated with the dorsal visual processing stream, such as global motion perception and visuomotor integration, may be impaired by preterm birth. These impairments can continue into adolescence and adulthood and may contribute to the difficulties in learning (particularly reading and mathematics), attention, behaviour and cognition that some children born preterm experience. Improvements in understanding the mechanisms by which preterm birth affects vision will inform future screening and interventions for children born preterm.

Motion Perception and Form Discrimination in Extremely Preterm School-Aged Children

This population-based study evaluated motion and form perception in 71 children born extreme premature (EPT; < 27 gestational weeks), aged 6.5 years, as compared to a matched group of 79 control children born at term. Motion and form perception were evaluated by motion coherence and form coherence tests. The EPT group showed a poorer performance on both tasks as compared to the control group. However, after controlling for IQ and visual acuity, the EPT group showed only a significant deficit in motion perception. No association was found between motion perception accuracy and gestational age, previous retinopathy of prematurity, or previous intraventricular hemorrhage in the EPT group. The results highlight the long-term motion perception deficits in children born EPT.

Visual perception in dyslexia is limited by sub-optimal scale selection

Readers with dyslexia are purported to have a selective visual impairment but the underlying nature of the deficit remains elusive. Here, we used a combination of behavioural psychophysics and biologically-motivated computational modeling to investigate if this deficit extends to object segmentation, a process implicated in visual word form recognition. Thirty-eight adults with a wide range of reading abilities were shown random-dot displays spatially divided into horizontal segments. Adjacent segments contained either local motion signals in opposing directions or analogous static form cues depicting orthogonal orientations. Participants had to discriminate these segmented patterns from stimuli containing identical motion or form cues that were spatially intermingled. Results showed participants were unable to perform the motion or form task reliably when segment size was smaller than a spatial resolution (acuity) limit that was independent of reading skill. Coherence thresholds decreased as segment size increased, but for the motion task the rate of improvement was shallower for readers with dyslexia and the segment size where performance became asymptotic was larger. This suggests that segmentation is impaired in readers with dyslexia but only on tasks containing motion information. We interpret these findings within a novel framework in which the mechanisms underlying scale selection are impaired in developmental dyslexia.

Encoding of rapid time-varying information is impaired in poor readers

A characteristic set of eye movements and fixations are made during reading, so the position of words on the retinae is constantly being updated. Effective decoding of print requires this temporal stream of visual information to be segmented or parsed into its constituent units (e.g., letters or words). Poor readers' difficulties with word recognition could arise at the point of segmenting time-varying visual information, but the mechanisms underlying this process are little understood. Here, we used random-dot displays to explore the effects of reading ability on temporal segmentation. Thirty-eight adult readers viewed test stimuli that were temporally segmented by constraining either local motions or analogous form cues to oscillate back and fourth at each of a range of rates. Participants had to discriminate these segmented patterns from comparison stimuli containing the same motion and form cues but these were temporally intermingled. Results showed that the motion and form tasks could not be performed reliably when segment duration was shorter than a temporal resolution (acuity) limit. The acuity limits for both tasks were significantly and negatively correlated with reading scores. Importantly, the minimum segment duration needed to detect the temporally segmented stimuli was longer in relatively poor readers than relatively good readers. This demonstrates that adult poor readers have difficulty segmenting temporally changing visual input particularly at short segment durations. These results are consistent with evidence suggesting that precise encoding of rapid time-varying information is impaired in developmental dyslexia.

Disentangling How the Brain is "Wired" in Cortical (Cerebral) Visual Impairment

Cortical (cerebral) visual impairment (CVI) results from perinatal injury to visual processing structures and pathways of the brain and is the most common cause of severe visual impairment or blindness in children in developed countries. Children with CVI display a wide range of visual deficits including decreased visual acuity, impaired visual field function, as well as impairments in higher-order visual processing and attention. Together, these visual impairments can dramatically influence a child's development and well-being. Given the complex neurologic underpinnings of this condition, CVI is often undiagnosed by eye care practitioners. Furthermore, the neurophysiological basis of CVI in relation to observed visual processing deficits remains poorly understood. Here, we present some of the challenges associated with the clinical assessment and management of individuals with CVI. We discuss how advances in brain imaging are likely to help uncover the underlying neurophysiology of this condition. In particular, we demonstrate how structural and functional neuroimaging approaches can help gain insight into abnormalities of white matter connectivity and cortical activation patterns, respectively. Establishing a connection between how changes within the brain relate to visual impairments in CVI will be important for developing effective rehabilitative and education strategies for individuals living with this condition.

The Davida Teller Award Lecture, 2016: Visual Brain Development: A review of "Dorsal Stream Vulnerability"-motion, mathematics, amblyopia, actions, and attention

Research in the Visual Development Unit on "dorsal stream vulnerability' (DSV) arose from research in two somewhat different areas. In the first, using cortical milestones for local and global processing from our neurobiological model, we identified cerebral visual impairment in infants in the first year of life. In the second, using photo/videorefraction in population refractive screening programs, we showed that infant spectacle wear could reduce the incidence of strabismus and amblyopia, but many preschool children, who had been significantly hyperopic earlier, showed visuo-motor and attentional deficits. This led us to compare developing dorsal and ventral streams, using sensitivity to global motion and form as signatures, finding deficits in motion sensitivity relative to form in children with Williams syndrome, or perinatal brain injury in hemiplegia or preterm birth. Later research showed that this "DSV" was common across many disorders, both genetic and acquired, from autism to amblyopia. Here, we extend DSV to be a cluster of problems, common to many disorders, including poor motion sensitivity, visuo-motor spatial integration for planning actions, attention, and number skills. In current research, we find that individual differences in motion coherence sensitivity in typically developing children are correlated with MRI measures of area variations in parietal lobe, fractional anisotropy (from TBSS) of the superior longitudinal fasciculus, and performance on tasks of mathematics and visuo-motor integration. These findings suggest that individual differences in motion sensitivity reflect decision making and attentional control rather than integration in MT/V5 or V3A. Its neural underpinnings may be related to Duncan's "multiple-demand" (MD) system.

Cerebral versus Ocular Visual Impairment: The Impact on Developmental Neuroplasticity

Cortical/cerebral visual impairment (CVI) is clinically defined as significant visual dysfunction caused by injury to visual pathways and structures occurring during early perinatal development. Depending on the location and extent of damage, children with CVI often present with a myriad of visual deficits including decreased visual acuity and impaired visual field function. Most striking, however, are impairments in visual processing and attention which have a significant impact on learning, development, and independence. Within the educational arena, current evidence suggests that strategies designed for individuals with ocular visual impairment are not effective in the case of CVI. We propose that this variance may be related to differences in compensatory neuroplasticity related to the type of visual impairment, as well as underlying alterations in brain structural connectivity. We discuss the etiology and nature of visual impairments related to CVI, and how advanced neuroimaging techniques (i.e., diffusion-based imaging) may help uncover differences between ocular and cerebral causes of visual dysfunction. Revealing these differences may help in developing future strategies for the education and rehabilitation of individuals living with visual impairment.

Individual differences in children's global motion sensitivity correlate with TBSS-based measures of the superior longitudinal fasciculus

Reduced global motion sensitivity, relative to global static form sensitivity, has been found in children with many neurodevelopmental disorders, leading to the "dorsal stream vulnerability" hypothesis (Braddick et al., 2003). Individual differences in typically developing children's global motion thresholds have been shown to be associated with variations in specific parietal cortical areas (Braddick et al., 2016). Here, in 125 children aged 5-12years, we relate individual differences in global motion and form coherence thresholds to fractional anisotropy (FA) in the superior longitudinal fasciculus (SLF), a major fibre tract communicating between parietal lobe and anterior cortical areas. We find a positive correlation between FA of the right SLF and individual children's sensitivity to global motion coherence, while FA of the left SLF shows a negative correlation. Further analysis of parietal cortical area data shows that this is also asymmetrical, showing a stronger association with global motion sensitivity in the left hemisphere. None of these associations hold for an analogous measure of global form sensitivity. We conclude that a complex pattern of structural asymmetry, including the parietal lobe and the superior longitudinal fasciculus, is specifically linked to the development of sensitivity to global visual motion. This pattern suggests that individual differences in motion sensitivity are primarily linked to parietal brain areas interacting with frontal systems in making decisions on integrated motion signals, rather than in the extra-striate visual areas that perform the initial integration. The basis of motion processing deficits in neurodevelopmental disorders may depend on these same structures.

Why is the processing of global motion impaired in adults with developmental dyslexia?

Individuals with dyslexia are purported to have a selective dorsal stream impairment that manifests as a deficit in perceiving visual global motion relative to global form. However, the underlying nature of the visual deficit in readers with dyslexia remains unclear. It may be indicative of a difficulty with motion detection, temporal processing, or any task that necessitates integration of local visual information across multiple dimensions (i.e. both across space and over time). To disentangle these possibilities we administered four diagnostic global motion and global form tasks to a large sample of adult readers (N=106) to characterise their perceptual abilities. Two sets of analyses were conducted. First, to investigate if general reading ability is associated with performance on the visual tasks across the entire sample, a composite reading score was calculated and entered into a series of continuous regression analyses. Next, to investigate if the performance of readers with dyslexia differs from that of good readers on the visual tasks we identified a group of forty-three individuals for whom phonological decoding was specifically impaired, consistent with the dyslexic profile, and compared their performance with that of good readers who did not exhibit a phonemic deficit. Both analyses yielded a similar pattern of results. Consistent with previous research, coherence thresholds of poor readers were elevated on a random-dot global motion task and a spatially one-dimensional (1-D) global motion task, but no difference was found on a static global form task. However, our results extend those of previous studies by demonstrating that poor readers exhibited impaired performance on a temporally-defined global form task, a finding that is difficult to reconcile with the dorsal stream vulnerability hypothesis. This suggests that the visual deficit in developmental dyslexia does not reflect an impairment detecting motion per se. It is better characterised as a difficulty processing temporal information, which is exacerbated when local visual cues have to be integrated across multiple (>2) dimensions.

Preterm birth is associated with atypical social orienting in infancy detected using eye tracking

BACKGROUND

Preterm birth is closely associated with neurocognitive impairment in childhood including increased risk for social difficulties. Eye tracking objectively assesses eye-gaze behaviour in response to visual stimuli, which permits inference about underlying cognitive processes. We tested the hypothesis that social orienting in infancy is altered by preterm birth.

METHODS

Fifty preterm infants with mean (range) gestational age (GA) at birth of 29(+1) (23(+2) -33(+0) ) weeks and 50 term infants with mean (range) GA at birth 40(+2) (37(+0) -42(+3) ) weeks underwent eye tracking at median age of 7 months. Infants were presented with three categories of social stimuli of increasing complexity. Time to first fixate (TFF) and looking time (LT) on areas of interest (AoIs) were recorded using remote eye tracking.

RESULTS

Preterm infants consistently fixated for a shorter time on social content than term infants across all three tasks: face-scanning (fixation to eyes minus mouth 0.61s vs. 1.47s, p = .013); face pop-out task (fixation to face 0.8s vs. 1.34s, p = .023); and social preferential looking (1.16s vs. 1.5s p = .02). Time given to AoIs containing social content as a proportion of LT at the whole stimulus was lower in preterm infants across all three tasks. These results were not explained by differences in overall looking time between the groups.

CONCLUSIONS

Eye tracking provides early evidence of atypical cognition after preterm birth, and may be a useful tool for stratifying infants at risk of impairment for early interventions designed to improve outcome.

Cortical processing of global form, motion and biological motion under low light levels

Advances in potential treatments for rod and cone dystrophies have increased the need to understand the contributions of rods and cones to higher-level cortical vision. We measured form, motion and biological motion coherence thresholds and EEG steady-state visual evoked potentials (SSVEP) responses under light conditions ranging from photopic to scotopic. Low light increased thresholds for all three kinds of stimuli; however, global form thresholds were relatively more impaired than those for global motion or biological motion. SSVEP responses to coherent global form and motion were reduced in low light, and motion responses showed a shift in topography from the midline to more lateral locations. Contrast sensitivity measures confirmed that basic visual processing was also affected by low light. However, comparison with contrast sensitivity function (CSF) reductions achieved by optical blur indicated that these were insufficient to explain the pattern of results, although the temporal properties of the rod system may also play a role. Overall, mid-level processing in extra-striate areas is differentially affected by light level, in ways that cannot be explained in terms of low-level spatiotemporal sensitivity. A topographical shift in scotopic motion SSVEP responses may reflect either changes to inhibitory feedback mechanisms between V1 and extra-striate regions or a reduction of input to the visual cortex. These results provide insight into how higher-level cortical vision is normally organised in absence of cone input, and provide a basis for comparison with patients with cone dystrophies, before and after treatments aiming to restore cone function.

Socio-Emotional Development Following Very Preterm Birth: Pathways to Psychopathology

Very preterm birth (VPT; < 32 weeks of gestation) has been associated with an increased risk to develop cognitive and socio-emotional problems, as well as with increased vulnerability to psychiatric disorder, both with childhood and adult onset. Socio-emotional impairments that have been described in VPT individuals include diminished social competence and self-esteem, emotional dysregulation, shyness and timidity. However, the etiology of socio-emotional problems in VPT samples and their underlying mechanisms are far from understood. To date, research has focused on the investigation of both biological and environmental risk factors associated with socio-emotional problems, including structural and functional alterations in brain areas involved in processing emotions and social stimuli, perinatal stress and pain and parenting strategies. Considering the complex interplay of the aforementioned variables, the review attempts to elucidate the mechanisms underlying the association between very preterm birth, socio-emotional vulnerability and psychopathology. After a comprehensive overview of the socio-emotional impairments associated with VPT birth, three main models of socio-emotional development are presented and discussed. These focus on biological vulnerability, early life adversities and parenting, respectively. To conclude, a developmental framework is used to consider different pathways linking VPT birth to psychopathology, taking into account the interaction between medical, biological, and psychosocial factors.

Development of Visual Motion Perception for Prospective Control: Brain and Behavioral Studies in Infants

During infancy, smart perceptual mechanisms develop allowing infants to judge time-space motion dynamics more efficiently with age and locomotor experience. This emerging capacity may be vital to enable preparedness for upcoming events and to be able to navigate in a changing environment. Little is known about brain changes that support the development of prospective control and about processes, such as preterm birth, that may compromise it. As a function of perception of visual motion, this paper will describe behavioral and brain studies with young infants investigating the development of visual perception for prospective control. By means of the three visual motion paradigms of occlusion, looming, and optic flow, our research shows the importance of including behavioral data when studying the neural correlates of prospective control.

The effect of blur on cortical responses to global form and motion

Global form and motion sensitivity undergo long development in childhood with motion sensitivity rather than form being impaired in a number of childhood disorders and both impaired in adult clinical populations. This suggests extended development and vulnerability of extrastriate cortical areas associated with global processing. However, in some developmental and clinical populations, it remains unclear to what extent impairments might reflect deficits at earlier stages of visual processing, such as reduced visual acuity and contrast sensitivity. To address this, we investigated the impact of degraded spatial vision on cortical global form and motion processing in healthy adults. Loss of high spatial frequencies was simulated using a diffuser to blur the stimuli. Participants completed behavioral and EEG tests of global form and motion perception under three levels of blur. For the behavioral tests, participants' form and motion coherence thresholds were measured using a two-alternative, forced-choice procedure. Steady-state visual evoked potentials were used to measure cortical responses to changes in the coherence of global form and motion stimuli. Both global form and global motion perception were impaired with increasing blur as measured by elevated behavioral thresholds and reduced cortical responses. However, form thresholds showed greater impairment in both behavioral and EEG measures than motion thresholds at the highest levels of blur. The results suggest that high spatial frequencies play an important role in the perception of both global form and motion but are especially significant for global form. Overall, the results reveal complex interactions between low-level factors and global visual processing, highlighting the importance of taking these factors into account when investigating extrastriate function in low vision populations.

Global motion perception is independent from contrast sensitivity for coherent motion direction discrimination and visual acuity in 4.5-year-old children

Global motion processing depends on a network of brain regions that includes extrastriate area V5 in the dorsal visual stream. For this reason, psychophysical measures of global motion perception have been used to provide a behavioral measure of dorsal stream function. This approach assumes that global motion is relatively independent of visual functions that arise earlier in the visual processing hierarchy such as contrast sensitivity and visual acuity. We tested this assumption by assessing the relationships between global motion perception, contrast sensitivity for coherent motion direction discrimination (henceforth referred to as contrast sensitivity) and habitual visual acuity in a large group of 4.5-year-old children (n=117). The children were born at risk of abnormal neurodevelopment because of prenatal drug exposure or risk factors for neonatal hypoglycemia. Motion coherence thresholds, a measure of global motion perception, were assessed using random dot kinematograms. The contrast of the stimuli was fixed at 100% and coherence was varied. Contrast sensitivity was measured using the same stimuli by fixing motion coherence at 100% and varying dot contrast. Stereoacuity was also measured. Motion coherence thresholds were not correlated with contrast sensitivity or visual acuity. However, lower (better) motion coherence thresholds were correlated with finer stereoacuity (ρ=0.38, p=0.004). Contrast sensitivity and visual acuity were also correlated (ρ=-0.26, p=0.004) with each other. These results indicate that global motion perception for high contrast stimuli is independent of contrast sensitivity and visual acuity and can be used to assess motion integration mechanisms in children.