Although Piaget’s writings preceded our current discoveries about the brain, his observations about cognitive development are strongly supported by contemporary neuroscience. The intellectual skills that Piaget studied are mediated by the prefrontal cortex, the area of the brain involved with complex cognitive processes. The frontal lobe is the last area of the brain to develop in childhood and much of its development takes place within the first decade of life. In fact, there is a peak period of synaptogenesis (creation of synapses, the connections between brain cells) in the first two years of life—during Piaget’s sensory-motor stage. Synaptogenesis continues at a rapid pace throughout the first decade of life, bringing us up to the doorstep of the formal operational stage. Myellination of the frontal lobe, or the insulation of brain cells by a fatty sheath that speeds up nerve impulses, is not completed until the mid-twenties, however, suggesting that cognitive development is far from complete in the teenage years.