Gerald Edelman, a Nobel Prize-winning scientist who was credited with unlocking mysteries of the immune and nervous systems and later ventured into ambitious studies of the human mind, died May 17 at his home in La Jolla, Calif. He was 84.
His son David Edelman confirmed the death and said his father had Parkinson's disease.
Once an aspiring violinist, Gerald Edelman ultimately pursued a scientific career that spanned decades and defied categorization. His Nobel Prize in physiology or medicine, which he shared in 1972 with the British scientist Rodney Porter, recognized his discoveries related to the chemical structure of antibodies.
Antibodies are agents used by the immune system to attack bacteria, viruses and other intruders in the body. But Dr. Edelman did not consider himself an immunologist.
He later embraced neuroscience, and particularly the study of how the nervous system is constructed beginning in the embryonic stage.
He was credited with leading the seminal discovery of a sort of cellular glue, called the neural cell adhesion molecule (NCAM), which allows nerve cells to bind to one another and form the circuits of the nervous system. But he concluded that such biochemical discoveries, however significant, could not fully elucidate the workings of the brain.
Dr. Edelman was associated for many years with Rockefeller University in New York City, where he directed the Neurosciences Institute that today is located in La Jolla. He delved into questions on the vanguard of neuroscience, including the study of human consciousness, and developed a theory of brain function called neural Darwinism.
Some scientists regarded his later work as unverifiable or muddled. The late Francis Crick, co-discoverer of the double-helix structure of DNA, was said to have dismissed neural Darwinism as "neural Edelmanism." Others admired Dr. Edelman for daring to broach one of the most vexing questions in science.
He "straddled ... frontier fields in biology and biomedical science in the last century," said Anthony-Samuel LaMantia, the director of the Washington-based George Washington Institute for Neuroscience, describing Dr. Edelman as "one of the major intellects in science."
In his earliest noted work, Dr. Edelman essentially mapped a key immunological structure -- the antibody -- that had previously been uncharted. "Never before has a molecule approaching this complexity been deciphered," The New York Times reported in 1969, when the extent of Dr. Edelman's findings were announced.
Dr. Edelman also was credited with recasting scientific understanding of how antibodies operate. When an antigen, or foreign agent, enters the body, a healthy immune system produces antibodies to attack it. Before Dr. Edelman's studies, many scientists accepted the notion that antibodies altered their characteristics in order to match the features of the antigen.
Dr. Edelman's research, which relied on the laboratory examination of quickly reproducing cancer cells, revealed another system in place, said Patricia Maness, a former colleague of Dr. Edelman's who today is a professor of biochemistry at the University of North Carolina at Chapel Hill.
Dr. Edelman led a similarly groundbreaking discovery in neuroscience. Before his work, scientists did not know with certainty how nerve cells combine to form the nervous system. Through his work, Dr. Edelman showed that nerve cells do not affix themselves to each another like Velcro, Mr. LaMantia explained.
Rather, two nerve cells connect when surface molecules -- NCAMs -- recognize each other, setting off a chemical reaction that links the cells and in time forms a system.
Later in his career, Dr. Edelman went beyond chemistry to develop his theory of brain function. He postulated that the brain is not like a computer, hard-wired for certain capacities, but rather is sculpted over time through experiences that strengthen neuronal connections.
Some scientists who seemingly should have been able to understand the theory said simply that they did not. Others regarded Dr. Edelman as a pioneer. Oliver Sacks, the noted neurologist and writer, credited him with having offered "the first truly global theory of mind and consciousness, the first biological theory of individuality and autonomy."
Gerald Maurice Edelman was born July 1, 1929, in New York City. His father was a general physician in the era when doctors made house calls.
After pursuing classical music training, Dr. Edelman shifted to the sciences, receiving a bachelor's degree in chemistry in 1950 from Ursinus College in Collegeville, Pa., and a medical degree in 1954 from the University of Pennsylvania.
Following service as an Army doctor in France, he received a doctorate in chemistry in 1960.
In addition to his other appointments, Dr. Edelman was a professor at the Scripps Research Institute in La Jolla. He wrote prolifically for academic audiences and general readers.