In 1957, Arvid Carlsson showed that dopamine was a neurotransmitter in the brain and not just a precursor of norepinephrine. This was the prevailing view at that time. He also developed an assay to measure dopamine in the brain and found that the highest regional concentration existed in the basal ganglia.

This finding led to his experiments on reserpine, which depleted dopamine and produced a loss of movement control. These symptoms were similar to the clinical symptoms seen in the neurological illness, Parkinsonism.

In 2000, The Nobel Prize in Physiology or Medicine was awarded jointly to Carlsson, Paul Greengard and Eric R. Kandel “for their discoveries concerning signal transduction in the nervous system.”