Illustration of a synapse between two dopamine neurons with Parkinson抯 disease, showing a decrease in nerve impulse transmission, due to a decrease in dopamine production. Dopamine is vital for nerve impulse transmission in the control of motor function. In the case of neurons with Parkinson抯 disease, the nerve impulse does not reach the striatum, the nerve structure that intervenes in voluntary and automatic motor function, correctly, which causes incoherent movement.