Torsten Wiesel Biography (1924-)

Nationality
American
Ethnicity
Swedish
Gender
Male
Occupation
neurophysiologist

Torsten Nils Wiesel was born on June 3, 1924, in Uppsala, Sweden, the son ofAnna-Lisa Bentzer Wiesel and Fritz S. Wiesel, the chief psychiatrist at the Beckomberga Mental Hospital in Stockholm. Wiesel entered medical school at theKarolinska Institute in Stockholm in 1941 and studied neurophysiology and psychiatry. In 1954, he received his medical degree, becoming an instructor atthe institute as well as an assistant in the Department of Child Psychiatry at Karolinska Hospital. Wiesel then came to the United States in 1955 to do postdoctoral work at the Wilmer Institute of Johns Hopkins School of Medicine.

At Johns Hopkins, Wiesel worked under Stephen Kuffler, whose exhaustive workhad proved that the vision of mammals is distinctly different from that of non-mammals. Wiesel became interested in the idea that the critical level of visual perception must take place in the brain of mammals. In 1958, Wiesel setoff with David Hubel on the research that would result in a new theory of visual perception.

Wiesel and Hubel studied the striate or visual cortex which is located at theback of the brain. They discovered which cells in the cortex responded to which pattern or level of light. They also conducted experiments to map the striate cortex by injecting the eyes of experimental animals with radioactivelylabeled amino acid. These amino acids would be taken up by the cell bodies ofthe retina and transported to cells in the visual cortex. In some cases, thevisual cortexes were dissected in order to see, by the use of autoradiographs or X-ray like photos, where the labeled amino acids actually ended up. Suchexperiments, begun in 1959, used both cats and macaque monkeys. That same year Kuffler was appointed a professor at the Harvard University Medical School, and Wiesel and Hubel joined him there. Wiesel was appointed assistant professor of physiology, and became a full professor in 1964.

The Wiesel-Hubel team soon began publishing the results of their experimentalmethod, and it was clear that they had uncovered new complexities to the visual process. Within the visual cortex itself, Wiesel and Hubel made two important discoveries. First they showed that there is a hierarchy of types of cells in the cortex, ranking from simple to complex to hypercomplex, depending on the information each is able to process. They termed the process of puttingthe millions of building blocks of visual information back together into a picture "convergence." Their second major discovery was a further organizationof the cortical cells into roughly vertical divisions of two types: orientation columns and ocular dominance columns. Within these columns are simple, complex, and hypercomplex cells working toward a progressive convergence of visualization. Until the time of Wiesel's and Hubel's work, it was assumed thatall cells of the cerebral cortex were more or less uniform. Wiesel and Hubelshowed that the visual cortex is constituted of a cell pattern, which appearsto be designed specifically for vision. As a result of their discovery, current theory now posits that the rest of the cerebral cortex may follow this form-follows-function rule.

Wiesel and Hubel researched another experimental model in which they used kittens to study the effect of various visual impairments on development. They discovered that if one eye were deprived of certain or all visual stimuli at three to five weeks of age, the central functioning of that eye would always be suppressed from cortical processing. Kittens, and by extension mammals in general, though born with a complete visual cortex, must still "learn" to see.Even if an early impairment is later corrected, the repaired eye will stillremain functionally impaired as far as the visual cortex is concerned. The realization that there is a critical stage for visual development revolutionized the field of pediatric ophthalmology, calling for the earliest possible intervention in cases of strabismus, or crossed eyes, and congenital cataracts.

By 1973 Wiesel succeeded Kuffler as chair of the Department of Neurobiology at Harvard, and was named the Robert Winthrop Professor of Neurobiology in 1974. In 1981, Wiesel and Hubel were awarded the Nobel Prize for Physiology or Medicine, sharing it with Sperry from Caltech. The Karolinska Institute in Stockholm, which administers the prize and where Wiesel began his professional career, praised Hubel and Wiesel for their discoveries concerning informationprocessing in the visual system. Wiesel and Hubel continued their close working relationship until Wiesel left Harvard in 1984 to head the neurobiology lab at Rockefeller University where he continued his researches on vision. In 1992 he was named president of Rockefeller University.

Weisel's first marriage, to Teiri Stenhammer, ended in divorce after 14 yearsin 1970. Wiesel was married again in 1973, to Grace Yee. The couple had onechild, Sara Elisabet. His second marriage also ended in divorce in 1981. Wiesel became a naturalized U.S. citizen in 1990.

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