Visual Cortical Response Variability in Infants at High Familial Likelihood for Autism.

Visual processing undergoes rapid refinement in the first year of life, supporting the emergence of higher-order cognitive, language, and motor functions. Visual evoked potentials (VEPs) provide a non-invasive measure of visual system maturation that may shed light on heterogeneous developmental trajectories among infants at high familial likelihood for autism. Infants with an older sibling with autism spectrum disorder (N = 177 at 6 months; N = 132 at 12 months) participated in the Infant Brain Imaging Study-Early Prediction (IBIS-EP) study. Pattern-reversal VEPs were recorded at 6 and 12 months, and developmental skills were assessed at 24 months using the Bayley Scales of Infant and Toddler Development (Bayley-III). VEP components were characterized by P1 amplitude, latency, and trial-to-trial variability in latency. Associations with 24-month cognitive, language, and motor scores were examined using general linear models controlling for age, site, sex, and trial count. Robust VEPs were observed at both timepoints, showing age-appropriate morphology and expected developmental changes, including decreases in P1 latency and amplitude from 6 to 12 months. Greater trial-to-trial variability in P1 latency at both timepoints was significantly associated with higher cognitive and language scores at 24 months. Variability in visual cortical response timing was the strongest neural correlate of developmental skills in infancy. These findings suggest that temporal variability in early neural responses may reflect adaptive sensory circuit flexibility rather than inefficiency, potentially facilitating experience-dependent tuning of visual pathways. VEPs offer a mechanistic window into how developing sensory systems scaffold individual differences in early developmental trajectories.