The primary goal of my current research is to understand the consequences of early general anesthesia in humans on brain structure, brain function, and cognition later during childhood. Substantial data indicate that general anesthesia causes neurotoxicity in young animals. Worldwide, millions of young human children have general anesthesia annually. This is of great public health concern given the possibility that early general anesthesia could cause abnormalities in brain structure, brain function, and cognition that could have life-long consequences. We use structural and functional magnetic resonance imaging to examine brain structure and function and their interrelationships in 12 – 15.9 year old children who had initial general anesthesia from birth to 3 years of age. We also perform out-of-scanner cognitive assessments including tests previously found to be sensitive to early general anesthesia, supplemented by a broader range of assessments from the NIH Toolbox for the Assessment of Neurological and Behavioral Functions. The ongoing study is simultaneously addressing the following three aims: (1) Evaluate the effects of general anesthesia during early childhood on measures of brain structure, brain function, and cognition during later childhood by comparing children with early general anesthesia involving a volatile agent to children who did not have early general anesthesia. (2) Compare effects of general anesthesia occurring at varying ages within the range of birth to 3 years, during high vs. low invasive procedures, and for varying durations of general anesthesia. (3) Assess influences of comorbidity and anesthetic drugs, e.g., how prematurity influences effects of early general anesthesia on brain structure, brain function, and cognition; and whether regional anesthesia has smaller effects than general anesthesia.