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Background Pragmatic language is key for adaptive communication, but often compromised in neurodevelopmental conditions such as autism spectrum disorder (ASD). Decontextualized language—to talk about events and things beyond here and now—develops early in childhood and can be seen as a pre-pragmatic ability. Little is known about the factors that contribute to decontextualized language use in toddlers and whether these are different from factors contributing to general language development. Methods We studied longitudinal associations between parent-rated core language and non-verbal socio-communicative abilities at 14 months of age, and decontextualized language use at 24 months of age in children with typical and elevated likelihood of ASD (total N = 303). Using twin modelling, we also investigated genetic and environmental contributions on decontextualized language and grammar use in two-year-old twin pairs (total N = 374). Results Core language ability was a strong predictor of later decontextualized language use in both children with and without an elevated likelihood of ASD. In contrast, social communication was only a significant predictor of decontextualized language use for children with low levels of core language. This pattern was specific to decontextualized language, and not replicated in prediction of concurrent grammatical ability. Further, there was a large genetic influence on decontextualized language at 2 years of age, which mostly overlapped with the genetic influences on grammatical ability. Shared environment influences were significant for grammatical ability, but not found on decontextualized language. In children with an elevated likelihood of ASD, decontextualized language use was negatively associated with autistic symptoms. Conclusions This study suggests that decontextualized language is developmentally associated with, yet dissociable from, more general language development measured as grammatical ability. Already at 2 years of age, par

BackgroundFrom birth, infants orient preferentially to faces, and when looking at the face, they attend primarily to eyes and mouth. These areas convey different types of information, and earlier research suggests that genetic factors influence the preference for one or the other in young children. MethodsIn a sample of 535 5-month-old infant twins, we assessed eye (relative to mouth) preference in early infancy, i.e., before neural systems for social communication and language are fully developed. We investigated the contribution of genetic and environmental factors to the preference for looking at eyes, and the association with concurrent traits and follow-up measures. ResultsEye preference was independent from all other concurrent traits measured, and had a moderate-to-high contribution from genetic influences (A = 0.57; 95% CI: 0.45, 0.66). Preference for eyes at 5 months was associated with higher parent ratings of receptive vocabulary at 14 months. No statistically significant association with later autistic traits was found. Preference for eyes was strikingly stable across different stimulus types (e.g., dynamic vs. still), suggesting that infants' preference at this age does not reflect sensitivity to low-level visual cues. ConclusionsThese results suggest that individual differences in infants' preferential looking to eyes versus mouth to a substantial degree reflect genetic variation. The findings provide new leads on both the perceptual basis and the developmental consequences of these attentional biases.

Background Measures based on pupillometry, such as the pupillary light reflex (PLR) and baseline pupil size, reflect physiological responses linked to specific neural circuits that have been implicated as atypical in some psychiatric and neurodevelopmental conditions. Methods We investigated the contribution of genetic and environmental factors to the baseline pupil size and the PLR in 510 infant twins assessed at 5?months of age (281 monozygotic and 229 dizygotic pairs), and its associations with common genetic variants associated with neurodevelopmental (autism spectrum disorder and attention deficit hyperactivity disorder) and mental health (bipolar disorder, major depressive disorder and schizophrenia) conditions using genome-wide polygenic scores (GPSs). Results Univariate twin modelling showed high heritability at 5?months for both pupil size (h2?=?.64) and constriction in response to light (h2?=?.62), and bivariate twin modeling indicated substantial independence between the genetic factors influencing each (rG?=?.38). A statistically significant positive association between infant tonic pupil size and the GPS for schizophrenia was found (??=?.15, p?=?.024), while there was no significant association with the GPS for autism or any other GPSs. Conclusions This study shows that some pupil measures are highly heritable in early infancy, although substantially independent in their genetic etiologies, and associated with common genetic variants linked to schizophrenia. It illustrates how genetically informed studies of infants may help us understand early physiological responses associated with psychiatric disorders which emerge much later in life.

Twin studies can help us understand the relative contributions of genes and environment to phenotypic trait variation, including attentional and brain activation measures. In terms of applying methodologies such as electroencephalography (EEG) and eye tracking, which are key methods in developmental neuroscience, infant twin studies are almost nonexistent. Here, we describe the Babytwins Study Sweden (BATSS), a multi-method longitudinal twin study of 177 MZ and 134 DZ twin pairs (i.e., 622 individual infants) covering the 5−36 month time period. The study includes EEG, eye tracking and genetics, together with more traditional measures based on in-person testing, direct observation and questionnaires. The results show that interest in participation in research among twin parents is high, despite the comprehensive protocol. DNA analysis from saliva samples was possible in virtually all participants, allowing for both zygosity confirmation and polygenic score analyses. Combining a longitudinal twin design with advanced technologies in developmental cognitive neuroscience and genomics, BATSS represents a new approach in infancy research, which we hope to have impact across multiple disciplines in the coming years.

Twin studies can help us understand the relative contributions of genes and environment to phenotypic trait variation, including attentional and brain activation measures. In terms of applying methodologies such as electroencephalography (EEG) and eye tracking, which are key methods in developmental neuroscience, infant twin studies are almost nonexistent. Here, we describe the Babytwins Study Sweden (BATSS), a multi-method longitudinal twin study of 177 MZ and 134 DZ twin pairs (i.e., 622 individual infants) covering the 5−36 month time period., Article The Babytwins Study Sweden (BATSS): A Multi-Method Infant Twin Study of Genetic and Environmental Factors Influencing Infant Brain and Behavioral Development Terje Falck-Ytter1,2,3, Linnea Hamrefors1,2, Monica Siqueiros Sanches2,4, Ana Maria Portugal2, Mark Taylor5, Danyang Li2,6, Charlotte Viktorsson1, Irzam Hardiansyah2, Lynnea Myers2,7,8, Lars Westberg9, Sven Bölte2,10,11, Kristiina Tammimies2,6 and Angelica Ronald12 1Development and Neurodiversity Lab (DIVE), Department of Psychology, Uppsala University, Uppsala, Sweden, 2Center of Neurodevelopmental Disorders (KIND), Centre for Psychiatry Research; Department of Women’s and Children’s Health, Karolinska Institutet and Stockholm Health Care Services, Stockholm, Sweden, 3Swedish Collegium for Advanced Study (SCAS), Uppsala, Sweden, 4Center for Interdisciplinary Brain Sciences Research, Department of Psychiatry and Behavioral Sciences, Stanford University, Stanford, CA, USA, 5Department of Medical Epidemiology & Biostatistics, Karolinska Institutet, Stockholm, Sweden, 6Astrid Lindgren Children’s Hospital, Karolinska University Hospital, Stockholm, Sweden, 7Department of Nursing, Gustavus Adolphus College, St. Peter, Minnesota, USA, 8Clinical Pediatrics, Department of Women’s and Children’s Health, Karolinska Institutet, Stockholm, Sweden, 9Department of Pharmacology, Institute of Neuroscience and Physiology at the Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden, 10Child and Adolescent Psychiatry, Stockholm Health Care Services, Stockholm, Sweden, 11Curtin Autism Research Group, Curtin School of Allied Health, Curtin University, Perth, Western Australia, Australia and 12Department of Psychological Sciences, Birkbeck, University of London, London, UK Abstract Twin studies can help us understand the relative contributions of genes and environment to phenotypic trait variation, including attentional and brain activation measures. In terms of applying methodologies such as electroencephalograp

Background: Visual exploration in autism spectrum disorder (ASD) is characterized by attenuated social attention. The underlying oculomotor function during visual exploration is understudied, whereas oculomotor function during restricted viewing suggested saccade dysmetria in ASD by altered pontocerebellar motor modulation. Methods: Oculomotor function was recorded using remote eye tracking in 142 ASD participants and 142 matched neurotypical controls during free viewing of naturalistic videos with and without human content. The sample was heterogenous concerning age (6–30 years), cognitive ability (60–140 IQ), and male/female ratio (3:1). Oculomotor function was defined as saccade, fixation, and pupil‐dilation features that were compared between groups in linear mixed models. Oculomotor function was investigated as ASD classifier and features were correlated with clinical measures. Results: We observed decreased saccade duration (∆M = −0.50, CI [−0.21, −0.78]) and amplitude (∆M = −0.42, CI [−0.12, −0.72]), which was independent of human video content. We observed null findings concerning fixation and pupil‐dilation features (POWER = .81). Oculomotor function is a valid ASD classifier comparable to social attention concerning discriminative power. Within ASD, saccade features correlated with measures of restricted and repetitive behavior. Conclusions: We conclude saccade dysmetria as ASD oculomotor phenotype relevant to visual exploration. Decreased saccade amplitude and duration indicate spatially clustered fixations that attenuate visual exploration and emphasize endogenous over exogenous attention. We propose altered pontocerebellar motor modulation as underlying mechanism that contributes to atypical (oculo‐)motor coordination and attention function in ASD.

During toddlerhood, a peak period of neurocognitive development, increased exposure to sensory stimulation through touch screen use, may influence developing attentional control. While TV’s rapidly changing, noncontingent flow of sensory information has been hypothesized to lead to difficulties voluntarily focusing attention, video gaming’s contingent and cognitively demanding sensory environments may improve visual processing and attention.3 Toddler touch screen use involves both exogenous attention, driven by salient audio-visual features, and endogenous/voluntary control, eg, video selection and app use. The current study compared high– and low–touch screen users on a gaze-contingent visual search paradigm, assessing exogenous, saliency-based attention (single-feature trials), and endogenous attention control (conjunction trials).

Background: Visual exploration in autism spectrum disorder (ASD) is characterized by attenuated social attention. The underlying oculomotor function during visual exploration is understudied, whereas oculomotor function during restricted viewing suggested saccade dysmetria in ASD by altered pontocerebellar motor modulation. Methods: Oculomotor function was recorded using remote eye tracking in 142 ASD participants and 142 matched neurotypical controls during free viewing of naturalistic videos with and without human content. The sample was heterogenous concerning age (6–30 years), cognitive ability (60–140 IQ), and male/female ratio (3:1). Oculomotor function was defined as saccade, fixation, and pupil-dilation features that were compared between groups in linear mixed models. Oculomotor function was investigated as ASD classifier and features were correlated with clinical measures. Results: We observed decreased saccade duration (∆M = −0.50, CI [−0.21, −0.78]) and amplitude (∆M = −0.42, CI [−0.12, −0.72]), which was independent of human video content. We observed null findings concerning fixation and pupil-dilation features (POWER = .81). Oculomotor function is a valid ASD classifier comparable to social attention concerning discriminative power. Within ASD, saccade features correlated with measures of restricted and repetitive behavior. Conclusions: We conclude saccade dysmetria as ASD oculomotor phenotype relevant to visual exploration. Decreased saccade amplitude and duration indicate spatially clustered fixations that attenuate visual exploration and emphasize endogenous over exogenous attention. We propose altered pontocerebellar motor modulation as underlying mechanism that contributes to atypical (oculo-)motor coordination and attention function in ASD.