The prefrontal cortex (PFC) is involved in important cognitive processes such as working memory, planning and decision making. The PFC is subject to a lengthy functional and anatomical maturation process in postnatal development, which is completed in the early adulthood. These processes ultimately lead to the fine tuning of the excitatory-inhibiting balance in local PFC microcircuits. Altered maturation of PFC microcircuits is likely to contribute to the susceptibility to mental illnesses such as schizophrenia, which manifest themselves only during adolescence and are associated with PFC-dependent cognitive impairments. The ventral tegmental region sends various inputs into the PFC, which together form the mesoprefrontal system: dopaminergic projections, glutamatergic projections and projections of neurons with the ability to release dopamine and glutamate. We are investigating whether there is a coordinated maturation process of the different components of the mesoprefrontal system and of the PFC microcircuits and how changes in mesoprefrontal inputs affect the formation of local networks in the PFC. Insights into the processes that influence PFC maturation during postnatal development will be instrumental for understanding the etiology of PFC-associated neuropsychiatric disorders.