Objective: The authors sought to determine whether specific patterns of oculomotor functioning and visual orienting characterize 7-month-old infants who later meet criteria for an autism spectrum disorder (ASD) and to identify the neural correlates of these behaviors. Method: Data were collected from 97 infants, of whom 16 were high-familialrisk infants later classified as having an ASD, 40 were high-familial-risk infants who did not later meet ASD criteria (high-risk negative), and 41 were lowrisk infants. All infants underwent an eyetracking task at a mean age of 7 months and a clinical assessment at a mean age of 25 months. Diffusion-weighted imaging data were acquired for 84 of the infants at 7 months. Primary outcome measures included average saccadic reaction time in a visually guided saccade procedure and radial diffusivity (an index of white matter organization) in fiber tracts that included corticospinal pathways and the splenium and genu of the corpus callosum. Results: Visual orienting latencies were longer in 7-month-old infants who expressed ASD symptoms at 25 months compared with both high-risk negative infants and low-risk infants. Visual orienting latencies were uniquely associated with the microstructural organization of the splenium of the corpus callosum in low-risk infants, but this association was not apparent in infants later classified as having an ASD. Conclusions: Flexiblyandefficientlyorienting to salient information in the environment is critical for subsequent cognitive and social-cognitive development. Atypical visual orienting may represent an early prodromal feature of an ASD, and abnormal functional specialization of posterior cortical circuits directly informs a novel model of ASD pathogenesis.
Bibliographical noteFunding Information:
We thank D. Binkley, V. J. Jaramillo, J. Meave and two anonymous reviewers for helpful comments on the manuscript, M. A. Quintana for field assistance, and E. Solís, R. Esteban, and P. Islas for help in chemical analysis. Departamento de Biología, Facultad de Química, UNAM provided all facilities for POM analysis. This work was supported by a M. Sc. scholarship to S. Núñez and a grant (0080N-9106) to A. Búrquez from Consejo Nacional de Ciencia y Tecnología, México, and from Dirección General de Asuntos del Personal Académico, UNAM (PAPIIT-IN212894).