Hubel and Wiesel's Visual Cortex Experiments

Beginning in the late 1950s the neurophysiologists David Hubel and Torsten Wiesel conducted a series of experiments recording the electrical activity of individual neurons in the primary visual cortex of cats, using microelectrodes to identify precisely what pattern of visual stimulation would cause a given neuron to fire. In their first major publication, in 1959, Hubel and Wiesel discovered that many neurons in the visual cortex responded not to spots of light in general but specifically to lines or edges oriented at a particular angle, a property they termed orientation selectivity, overturning the simpler view that visual cortical neurons responded to visual stimuli much the way retinal neurons did. Their subsequent 1962 paper described how these orientation-selective neurons were organized into functional columns running vertically through the cortex, with neurons in the same column sharing a preferred orientation, and introduced the concept of ocular dominance, regions of cortex in which neurons showed a preference for input from one eye over the other. In further experiments during the 1960s, Hubel and Wiesel showed that visual experience during a limited critical period early in a kitten's life was essential for the normal development of these cortical response properties, since temporarily closing one eye during this window produced lasting deficits in the brain's processing of input from that eye. Their combined body of work established the basic architecture of how the visual cortex processes information and earned Hubel and Wiesel a share of the 1981 Nobel Prize in Physiology or Medicine.