. . . "rst year and reach 1.5x their birth length by the end of first year ??? ??? ??? Cerebral Cortex This part of the brain is responsible for 80% of brain volume and is critical in perception, thinking, language and other functions, particularly the prefrontal cotrex ??? ??? ??? Prefrontal Cortex The cerebral cortex is critical for many functions including this cortex ??? ??? ??? Frontal Lobes This pa" .