Single Dose Double-blind, Placebo-controlled Cross-over (SDDBPCCO) Shiftability Study, Will be Followed by a 10-week Open-label Study With Arbaclofen (4 Weeks of Titration and Then 6 Weeks of Active/Stable Treatment). The Effects of Arbaclofen on Target EEG and ERG Metrics Will be Associated With th

study with arbaclofen (4 weeks of titration and then 6 weeks of active/stable treatment). The effects of arbaclofen on target EEG and ERG metrics will be associated with the clinical response in measures of social and general function, adaptive behaviour, social anxiety, sensory behaviours, global functioning, and quality of life in Children and Adolescents with Autism Spectrum Disorders