The answer is prefrontal cortex. This is a part of the frontal lobe. The frontal lobe like other lobes has some functional areas. These areas of the brain are associated with a particular purpose. One of the functional areas of the frontal lobe is the prefrontal cortex. This area is associated with the cognitive skills like concentration, emotion, and other higher brain functions.
Adolescents may lack the cognitive skills to control their impulses effectively because of the relatively slow development of the