Dopamine adrenaline and noradrenaline are transmitters that belong to the catecholamine category. Dopamine is created in the ventral tegmental region and substantia nigra part of the brain. Impairments in the dopamine system can result from these regions of the brain. The first dopamine hypothesis states that hyperactive dopamine transmission creates schizophrenia-like symptoms. This was created based upon the discover of dopamine as a transmitter. However, many researchers questioned the associated between dopamine activity and schizophrenic symptoms.