<qa>  What is the role of anesthesia and surgery on cognitive abilities?In order to investigate the role of anesthesia and or surgery on cognitive abilities the investigators want to perform a prospective cohort study in children under 3 years. Three groups should be compared: i control without anesthesia surgery, ii children with only anesthesia, and iii children with both surgery and anesthesia. All children will be investigate before and after intervention. Different behavioral scales will be used for detailed cognitive abilities and self-regulatory skills. 