Within the context of early infant–caregiver interaction, we review a series of pivotal transitions that occur within the first 6 months of typical infancy, with emphasis on behavior and brain mechanisms involved in preferential orientation towards, and interaction with, other people. Our goal in reviewing these transitions is to better understand how they may lay a necessary and/or sufficient groundwork for subsequent phases of development, and also to understand how the breakdown thereof, when development is atypical and those transitions become derailed, may instead yield disability. We review these developmental processes in light of recent studies documenting disruptions to early-emerging brain and behavior mechanisms in infants later diagnosed with autism spectrum disorder, shedding light on the brain–behavior pathogenesis of autism.
Autism spectrum disorder (autism) is a highly prevalent and heterogeneous family of neurodevelopmental disorders of genetic origins with potentially devastating implications for child, family, health and educational systems. Despite advances in paper-and-pencil screening and in standardization of diagnostic procedures, diagnosis of autism in the US still hovers around the ages of four or five years, later still in disadvantaged communities, and several years after the age of two to three years when the condition can be reliably diagnosed by expert clinicians. As early detection and treatment are two of the most important factors optimizing outcome, and given that diagnosis is typically a necessary condition for families to have access to early treatment, reducing age of diagnosis has become one of the greatest priorities of the field. Recent advances in developmental social neuroscience promise the advent of cost-effective and community- viable, performance-based procedures, and suggest a complementary method for promoting universal screening and much greater access to the diagnosis process. Small but critical studies have already reported on experiments that differentiate groups of children at risk for autism from controls, and at least one study so far could predict diagnostic classification and level of disability on the basis of a brief experiment. Although the road to translating such procedures into effective devices for screening and diagnosis is still a long one, and premature claims should be avoided, this effort could be critical in addressing this worldwide public health challenge.
Efforts to determine and understand the causes of autism are currently hampered by a large disconnect between recent molecular genetics findings that are associated with the condition and the core behavioral symptoms that define the condition. In this perspective piece, we propose a systems biology framework to bridge that gap between genes and symptoms. The framework focuses on basic mechanisms of socialization that are highly-conserved in evolution and are early-emerging in development. By conceiving of these basic mechanisms of socialization as quantitative endophenotypes, we hope to connect genes and behavior in autism through integrative studies of neurodevelopmental, behavioral, and epigenetic changes. These changes both lead to and are led by the accomplishment of specific social adaptive tasks in a typical infant's life. However, based on recent research that indicates that infants later diagnosed with autism fail to accomplish at least some of these tasks, we suggest that a narrow developmental period, spanning critical transitions from reflexive, subcortically-controlled visual behavior to interactional, cortically-controlled and social visual behavior be prioritized for future study. Mapping epigenetic, neural, and behavioral changes that both drive and are driven by these early transitions may shed a bright light on the pathogenesis of autism.