David H. Hubel

(b. 1926)

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(1926–) Canadian–American neurophysiologist

Born in Windsor, Ontario, Hubel was educated at McGill University and then worked at the Montreal Neurological Institute. He moved to America in 1954 and after working at Johns Hopkins joined the Harvard Medical School in 1959 where he was appointed professor of neurobiology from 1968 to 1982.

Beginning in the 1960s, Hubel, in collaboration with the Swedish neurophysiologist Torsten Wiesel (1924– ), published a number of remarkable papers that explained for the first time the mechanism of visual perception at the cortical level.

Their work was made possible by a number of technical advances. From the early 1950s onward it became possible to use microelectrodes to monitor the activity of a single neuron. Further, the work of Louis Sokoloff allowed workers to identify precise areas of neural activity. Using this latter technique it was thus possible to identify the region known as the striate cortex, located at the back of the cortex in the occipital lobes, as one of the key centers of activity during the visual process.

The cells of the striate cortex seemed to be arranged into columns, or ‘hypercolumns’ as they were soon described, that run the length of the cortex (3–4 millimeters) from the outer surface to the underlying white matter. Such hypercolumns were further clearly divided into distinct layers. Hubel and Weisel went on to probe the structure, function, and contents of such columns in great detail.

Above all they succeeded in establishing two crucial points. First that the retinal image was mapped in some way on to the striate cortex. That is, to each point on the retina there corresponded a group of cells in the striate cortex that would respond to a stimulation of that point and of no other.

Furthermore, the response could be evoked only by a relatively precise stimulus. Thus there were cells that would respond to a spot of light but not to a line. Cells that responded to lines would do so only to those lines with a specific tilt and if the angle of tilt was changed by as little as 10°, in either direction, the cells' ability to react would be diminished or even abolished.

As a result of such work the visual cortex has become the best known of all cortical regions. Hubel and Wiesel shared the 1981 Nobel Prize for physiology or medicine with Roger Sperry.

Subjects: Science and Mathematics.

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