Arvid Carlsson, Paul Greengard and Eric Kandel will share a $915,000 prize for their pioneering discoveries concerning "slow synaptic transmission,'' one way that brain cells send messages to each other.
These discoveries have been crucial for understanding how the brain normally works. In addition, they laid the groundwork for developing the standard treatment for Parkinson's disease and contributed to the development of a class of antidepressants that includes Prozac, the Nobel Assembly at Karolinska Institute said.
Carlsson, 77, is with the University of Goteborg in Sweden; Greengard, 74, is with Rockefeller University in New York; and Kandel, 70, is an Austrian-born U.S. citizen with Columbia University in New York.
The medicine prize was the first announced in a week of awards.
The winners of the prizes for physics and chemistry will be announced Tuesday and for economics â€“ the only one of the prizes not established in Nobel's will â€“ on Wednesday in Stockholm.
The awards culminate Friday with the coveted Peace Prize in Oslo, Norway. The date for the literature prize, also announced in Stockholm, has not yet been set.
Carlsson said he was thrilled to learn Monday morning that he had won.
"What shall I say, you get glad of course, overwhelmed,'' he said in an interview with Swedish radio.
Carlsson's studies during the late 1950s led to the development of the drug L-dopa, still the most important treatment for the disease, the committee said.
His research also shed light on how other drugs work, especially antipsychotic drugs used against schizophrenia.
Carlsson's work has contributed strongly to the development of a generation of anti-depression drugs called SSRIs (selective serotonin reuptake inhibitors), which include Prozac, the Nobel committee said.
"The discoveries of Arvid Carlsson have had great importance for the treatment of depression, which is one of our most common diseases,'' the citation said.
Greengard was honored for showing how brain cells respond to dopamine and other chemical messengers.
Kandel was cited for his research on the biology of memory, showing the importance of changes in the synapse, the place where chemical messages pass from one brain cell to another.
Tim Bliss, head of neuroscience at the National Institute for Medical Research in London, said Kandel's work â€“ dating to the 1960s â€“ could someday lead to new treatments for Alzheimer's disease and other conditions involving memory loss.