 Tonic transmission is regulated by a variety of factors, including the activity of other neurons and neurotransmitter reuptake.Inside the brain, dopamine plays important roles in executive functions, motor control, motivation, arousal, reinforcement, and reward, as well as lower-level functions including lactation, sexual gratification, and nausea.The dopaminergic cell groups and pathways make up the dopamine system which is neuromodulatory.