Development of cognition (knowledge about the world), language, and motor skills is highly correlated with brain development. We know that brain development begins during pregnancy. During the 16th week of gestation, cells in your baby’s brain began dividing. Growth occurs very rapidly in the brain stem, which controls basic functions, such as breathing, and in the primary motor (movement) and somatic sensory (hearing, vision, etc.) areas. At birth, your baby’s brain weights about 335 grams—about 25% of your adult brain weight of 1320 grams. After birth and during the first year, the brain grows fast, to about 70% of its adult size by 12 months. Development during this period is important, and is evident in the various areas that we will be covering.