Rapid eye movements in sleep: probe into infant visual brain development in autism

Abstract Autism spectrum disorder (ASD) is a heterogeneous, lifelong neurodevelopmental disorder. One in five infant siblings of children with ASD later receive an ASD diagnosis. With the aim of early detection and intervention, the Infant Brain Imaging Study Network conducted magnetic resonance imaging (MRI) studies of infant siblings, typically during sleep, and recently cited aberrant visual brain development as a potential MRI marker of ASD. Event-related functional MRI findings showed that rapid eye movements (REMs) in sleep index the processing of endogenous visual information, i.e., hierarchical generation of visual percepts. REM-locked peak activation sites and neural processing overlap extensively with those reported to be atypical in autism. Simply timing REMs may improve the accuracy of early detection, identify markers for stratification of heterogeneous ASD patients, and shed light on the typical and atypical development of visual perception and multisensory-motor integration. The strengths of REMs as a probe in functional brain imaging studies of infants are manifold. REMs serve as a task-free probe useful for studying both infants and animals, who cannot comply with conventional visual activation tasks. The REM-probe controls the level of attention across both the lifespan and typical-atypical neurodevelopment, and allows straightforward comparison of animal and human data.