3. To validate the neuropsychological functioning (e.g., set-shifting, executive function, and visuo-spatial memory etc.) and structural (morphometric,, cortical thickness, gyrification, white matter tract integrity) and functional connectivity (resting-state and social task fMRI) in fronto-temporal, cortico-striato-thalamic, default mode network, and other circuits as effective imaging endophenotypes (biomarkers) by demonstrating the stability of these imaging data and the intermediate position of unaffected siblings between ASD probands and age-, sex-, handedness-, and IQ-matched TD at Time 1 and follow-up.