Infants' looking preferences for social versus non-social objects reflect genetic variation

Ultra-high resolution imaging of laminar thickness in face-selective cortex in autism

Gray matter cortical thickness (CT) is related to perceptual abilities. The fusiform face area (FFA) (Kanwisher et al., The Journal of Neuroscience: The Official Journal of the Society for Neuroscience, 17, 4302-4311, 1997) in the inferior temporal lobe is defined by its face selectivity, and the CT of the FFA correlates with the ability to make difficult visual decisions (Bi et al., Current Biology, 24, 222-227, 2014; McGugin et al., Journal of Cognitive Neuroscience, 28, 282-294, 2016, Journal of Cognitive Neuroscience, 32, 1316-1329, 2020). In McGugin et al. Journal of Cognitive Neuroscience, 32, 1316-1329, (2020), individuals with better face recognition had relatively thinner FFAs, whereas those with better car recognition had thicker FFAs. This opposite correlation effect (OCE) for faces and cars was pronounced when we look selectively at the deepest laminar subdivision of the FFA. The OCE is thought to arise because car and face recognition abilities are fine-tuned by experience during different developmental periods. Given autism's impact on face recognition development, we predicted the OCE would not appear in autistic individuals. Our results replicate the OCE in total FFA thickness and in deep layers in neurotypical adults. Importantly, we find a significant reduction of these effects in adults with autism. This supports the idea that the OCE observed in neurotypical adults has a developmental basis. The abnormal OCE in autism is specific to the right FFA, suggesting that group differences depend on local specialization of the FFA, which did not occur in autistic individuals.

Autism-like atypical face processing in Shank3 mutant dogs

Atypical face processing is a neurocognitive basis of social deficits in autism spectrum disorder (ASD) and a candidate cognitive marker for the disease. Although hundreds of risk genes have been identified in ASD, it remains unclear whether mutations in a specific gene may cause ASD-like atypical face processing. Dogs have acquired exquisite face processing abilities during domestication and may serve as an effective animal model for studying genetic associations of ASD-like atypical face processing. Here, we showed that dogs with Shank3 mutations exhibited behavioral and attentional avoidance of faces, contrasting with wild-type controls. Moreover, neural responses specific to faces (versus objects) recorded from the electrodes over the temporal cortex were significantly decreased and delayed in Shank3 mutants compared to wild-type controls. Cortical responses in the frontal/parietal region underlying categorization of faces by species/breeds were reduced in Shank3 mutants. Our findings of atypical face processing in dogs with Shank3 mutations provide a useful animal model for studying ASD mechanisms and treatments.

Sit and face the world: ontogenetic adaptation in infant vocal production and visual attention during the transition to independent sitting

BACKGROUND

Motor milestones are not only indicators of developmental progress, but they also open up new opportunities for infants to interact with the environment and social partners, as the development of motor, social, and language skills is tightly interconnected in infancy. This study will investigate how the transition to independent sitting relates to key areas of socio-communicative development in infancy: vocal production and visual attention.

METHODS

This study addresses the relationship between sitting acquisition and social cognition skills in infancy. It will allow for comparing if infant motor development, vocalizations, and visual attention undergo developmental changes in parallel or whether they have intertwined trajectories. We will conduct a longitudinal study using a milestone-based approach to account for individual differences in relation to the timing of motor milestone acquisition. We will invite parent-infant dyads to the lab when infants are at different stages of independent sitting acquisition: non-sitting, attempting-sitting and expert-sitting. Infants' attention toward faces and toys will be measured with a wearable eye-tracker during free-flowing dyadic interactions with their caregivers. During the same interactions, infant vocalizations will also be recorded and analyzed. Additionally, screen-based eye-tracking will be used to precisely assess changes in infants' attention to the mouth area of the speaker.

DISCUSSION

Altogether, this study will provide a unique dataset that tracks the cross-dependence of motor, visual and vocal developmental trajectories. It will have the potential to inform future studies of neurodevelopmental disorders such as autism that are characterized by socio-communicative challenges.

Genetic and environmental contributions to individual differences in visual attention and oculomotor control in early infancy

Infants differ in their level of eye movement control, which at the extreme could be linked to autism. We assessed eye movements in 450 twins (225 pairs, 57% monozygotic, 46% female, aged 5-6 months) using the gap-overlap eye-tracking task. Shorter latency in the gap condition was associated with having more parent-rated autistic traits at 2 years. Latency across the task's three conditions was primarily explained by one highly heritable latent factor likely representing individual differences in basic oculomotor efficiency and/or in visual information processing. Additionally, disengagement of attention was linked to unique genetic factors, suggesting that genetic factors involved in visual attention are different from those involved in basic visual information processing and oculomotor efficiency.

Data retention in awake infant fMRI: Lessons from more than 750 scanning sessions

Functional magnetic resonance imaging (fMRI) in awake infants has the potential to reveal how the early developing brain gives rise to cognition and behavior. However, awake infant fMRI poses significant methodological challenges that have hampered wider adoption. The present work takes stock after the collection of a substantial amount of awake infant fMRI data across multiple studies from two labs at different institutions. We leveraged these data to glean insights on participant recruitment, experimental design, and data acquisition that could be useful to consider for future studies. Across 766 awake infant fMRI sessions, we explored the factors that influenced how much usable data were obtained per session (average of 9 minutes). The age of an infant predicted whether they would successfully enter the scanner (younger was more likely) and, if they did enter, the number of minutes of functional data retained after preprocessing. The amount of functional data retained was also influenced by assigned sex (female more), experimental paradigm (movies better than blocks and events), and stimulus content (social better than abstract). In addition, we assessed the value of attempting to collect multiple experiments per session, an approach that yielded more than one usable experiment averaging across all sessions (including those with no data). Although any given scan is unpredictable, these findings support the feasibility of awake infant fMRI and suggest practices to optimize future research.

Early selective attention to the articulating mouth as a potential female-specific marker of better language development in autism: a review

Autism is a neurodevelopmental condition with early onset, usually entailing language differences compared to neurotypical peers. Females are four times less likely than males to be diagnosed with autism, and the language features associated with this condition are less frequent in females than in males. However, the developmental mechanisms underlying these sex differences remain unclear. In neurotypical populations, sex differences in language development are also observable from early on, with females outperforming males. One mechanism underlying these sex differences may be early differences in selective attention to talking faces. During the first year, more mouth-looking generally predicts better language development, but sex differences exist. Female infants look at the mouth of a talking face more than males without penalizing looking to the eyes, and reduced mouth-looking in early infancy relates to better vocabulary in toddlerhood only in females. In this hypothesis and theory article, we propose that unique female gaze patterns to the mouth may constitute an early female-specific candidate marker that acts as a protective marker for language development also in autism. Since autism is highly heritable, investigating infants at elevated likelihood for autism offers the opportunity to search for sex-specific markers operating early in life before autistic features and language differences emerge. We argue that, as in neurotypical female infants, mouth-looking may also protect female infants-at-elevated-likelihood-for-autism population from potential later differences in language skills. If so, then sex-specific early behavioral markers, potentially acting as protective markers of language, may compensate for some genetic risk markers affecting this population. Here we gather evidence from neurotypical infants and those with elevated likelihood of autism to uncover why biological sex, the development of selective attention to the mouth, and language acquisition could be intimately related in both populations. We also propose hypotheses regarding potential sex-differentiated neurodevelopmental pathways. We end discussing future research challenges: how generalizable mouth-looking could be as a potential female-specific early language marker across contexts (experimental vs. real life), countries, and developmental time. Ultimately, we aim to target a novel protective candidate of language acquisition, informing tailored interventions that consider sex as an important source of individual variability.

Dissociable genetic influences on eye movements during abstract versus naturalistic social scene viewing in infancy

Eye-movement metrics like fixation location and duration are increasingly being used in infancy research. We tested whether fixation durations during meaningful social stimulus viewing involve common or different familial influences than fixation durations during viewing of abstract stimulus. We analysed the duration of fixations, and the allocation of fixations to face and motion, from 536 dizygotic and monozygotic 5-month-old twins in: naturalistic scenes including low- and high-level social features, and abstract scenes only having low-level features. We observed significant genetic influences in both conditions (h2naturalistic = 0.30, 95% confidence interval (CI) 0.14 to 0.44; h2abstract = 0.25, 95% CI 0.09 to 0.39), while shared environmental influences were negligible. Although some genetic influences were shared between the two conditions, unique genetic factors were linked to naturalistic scene viewing, indicating that fixation durations index different phenomena dependent on the context. Heritability for face looking was moderate (h2 = 0.19, 95% CI 0.03 to 0.34), and no familial influences were found for motion looking. Exploratory polygenic score analyses revealed no significant associations with fixation measures. This study underscores the dissociable genetic influences on infants' visual exploration of abstract versus naturalistic stimuli and the importance of considering context when interpreting eye-tracking data.

Social cognition in autism and ADHD

Social cognition is a crucial capacity for social functioning. The last decades have seen a plethora of social cognition research in neurodevelopmental conditions, foremost autism and, to a lesser extent, ADHD, both characterized by social challenges. Social cognition is a multifaceted construct comprising various overlapping subdomains, such as Theory of Mind/mentalizing, emotion recognition, and social perception. Mechanisms underpinning social cognition are complex, including implicit and explicit, cognitive and affective, and hyper- and hypo-social information processing. This review explores the intricacies of social cognition in the context of autism and ADHD. Research indicates altered performance on social cognition tests in autism, compared to neurotypical groups, with social cognition alterations having a small but robust effect on the defining features of autism. The nature of such alterations in autism appears primarily in relation to implicit processing. ADHD groups show intermediate social cognition performance, appearing to be influenced by executive function difficulties. Social cognition varies with intellectual and verbal abilities and seems to improve with age in autism and ADHD. Social skills interventions in autism, and stimulant medication in ADHD have been shown to improve social cognition test performance, while mentalizing training effects in autism are less conclusive. A limitation of the field is that social cognition constructs and tests are not well delineated. Further, most research has been embedded in a nativist approach rather than a constructivist approach. The former has been questioned for ignoring environmental contributions, especially the dimension of mutual miscommunication between neurodivergent and neurotypical individuals.

The breakdown of social looking

Individual differences in social looking are commonly believed to reflect one single heritable dimension tightly linked to autism. Yet, recent data suggest that in human infants, looking to eyes (rather than mouth) and preference for faces (versus non-social objects) reflect distinct genetic influences, and neither appear to have a clear-cut relation to autism.

Genetic and environmental contributions to gaze lateralization across social and non-social stimuli in human infants

A tendency to look at the left side of faces from the observer's point of view has been found in older children and adults, but it is not known when this face-specific left gaze bias develops and what factors may influence individual differences in gaze lateralization. Therefore, the aims of this study were to estimate gaze lateralization during face observation and to more broadly estimate lateralization tendencies across a wider set of social and non-social stimuli, in early infancy. In addition, we aimed to estimate the influence of genetic and environmental factors on lateralization of gaze. We studied gaze lateralization in 592 5-month-old twins (282 females, 330 monozygotic twins) by recording their gaze while viewing faces and two other types of stimuli that consisted of either collections of dots (non-social stimuli) or faces interspersed with objects (mixed stimuli). A right gaze bias was found when viewing faces, and this measure was moderately heritable (A = 0.38, 95% CI 0.24; 0.50). A left gaze bias was observed in the non-social condition, while a right gaze bias was found in the mixed condition, suggesting that there is no general left gaze bias at this age. Genetic influence on individual differences in gaze lateralization was only found for the tendency to look at the right versus left side of faces, suggesting genetic specificity of lateralized gaze when viewing faces.