Axel, Richard (1946-…), an American neuroscientist, won the 2004 Nobel Prize in physiology or medicine for his research on the sense of smell. He shared the Nobel Prize with another American neuroscientist, Linda B. Buck, who worked with Axel researching the genetic control of the sense of smell. The scientific term for smell is olfaction, and the system by which human beings and other animals smell is known as the olfactory system.
People detect smells by breathing in air that carries odors. Odors come from molecules that have been released into the air from many different substances. These molecules stimulate olfactory receptor cells inside the nose. The receptor cells send the impulses created by the odor along the olfactory nerve. The nerve impulses travel to the brain, which processes the impulses into information about the odor.
In 1991, Axel and Buck together discovered the family of genes that control the production of odor receptors in human beings and other animals. Each human body cell contains 23 pairs of chromosomes and an estimated 20,000 to 30,000 genes. Axel, Buck, and others have identified about 350 active odor receptor genes in human beings. This number represents about 1 percent of all genes that make up a human being. Each one of these active genes produces a unique type of odor receptor. Scientists were surprised to learn that human beings have as many as 350 different types of odor receptors. In comparison, the human eye contains just four types of light receptors.
Through a series of laboratory experiments in the 1990’s, Axel and Buck, working independently, discovered that each olfactory receptor cell is sensitive to multiple types of odor molecules. Most odors are made up of many different molecules, which stimulate many individual receptors in the nose. The pattern of nerve impulses received from hundreds of different odor receptors is processed by the brain to create the sensation of different odors that people experience.
Axel was born in New York City on July 2, 1946. He graduated from Columbia University in New York City in 1967 and received an M.D. degree from Johns Hopkins University in Baltimore in 1971. He conducted research at the Columbia University Institute of Cancer Research and at the United States National Institutes of Health (NIH). In 1974, he joined the faculty in the department of pathology at Columbia University, where he was named a professor in both pathology and biochemistry in 1978. In 1999, he was named University Professor, the highest academic rank at Columbia University. Since 1984, Axel has also held a research position with the Howard Hughes Medical Institute, a nonprofit medical research organization.
See also Buck, Linda B. ; Smell (How odors are detected) .
