My project studies how brain development during adolescence influences motivation in a non-human primate model, the common marmoset. During adolescence, social and cognitive skills, such as learning and memory, continue to develop. This coincides with extensive structural change in the brain, particularly in the prefrontal cortex. We believe that this structural change, especially the new connections being formed in the prefrontal cortex, may affect how the brain regulates motivation. New connections that change the way the brain controls motivation during adolescence could potentially lead to wide fluctuations and make motivation sensitive to other events in life such as increased stress. By learning how brain development in the marmoset prefrontal cortex affects motivation during adolescence, we hope to better understand how developmental changes in the human prefrontal cortex may contribute to the increasing prevalence of depressive symptoms among teenagers.