The frontal lobes are the largest part of the human brain, and thought to be the part that expanded most during human evolution. Damage to the frontal lobes—which are located just behind and above the eyes—can result in profound impairments in higher-level reasoning and decision making. To find out more about what different parts of the frontal lobes do, neuroscientists at the California Institute of Technology (Caltech) recently teamed up with researchers at the world’s largest registry of brain-lesion patients. By mapping the brain lesions of these patients, the team was able to show that reasoning and behavioral control are dependent on different regions of the frontal lobes than the areas called upon when making a decision.