David Hubel (b.1926) Canadian neurophysiologist and Nobel Laureate. Hubel qualified in medicine at McGill University, Montreal, and since 1959 has worked at Harvard. His research has centred on understanding visual perception in the cortex of the brain. Hubel and his colleague Weisel found that retinal stimulation causes excitation of particular cells in the striate cortex. This cell activation is very specific, different excitation is caused by different sources (points, lines, colours, directions of movement, etc.). Hubel also showed that many of these responses are present at birth, but may be modified in later life. This work won the 1981 Nobel Prize for Physiology.