Dopamine neurotransmitter molecule. Computer model showing the molecular structure of the human neurotransmitter and hormone dopamine. Atoms are represented as spheres and are colour-coded - carbon: black, hydrogen: white, nitrogen: blue, and oxygen: red - with the bonds between them as rods (silver). Dopamine plays a crucial role in the brain's reward and pleasure pathways. It is released by the brain when a pleasurable new stimulus is encountered, and directs the brain to find more of the stimulus. As such it plays a significant role in addiction. Lack of dopamine is linked to numerous disorders, such as Parkinson's disease, depression and schizophrenia.