Abstract
Hubel & Wiesel's remarkable 1962 paper on the cat's primary visual cortex played a major part in my decision to abandon medicine and become a vision researcher and I was fortunate to work for my PhD with Horace Barlow in Berkeley from 1965–8. I wanted to follow up Hubel & Wiesel's discovery that V1 neurons are binocularly driven by looking at the similarity of preferred orientation in the two eyes (but didn't get around to it until Blakemore, Fiorentini & Maffei, 1972) and at the responses of binocular neurons under conditions of binocular rivalry (but didn't do that until Sengpiel & Blakemore, 1994). Horace Barlow, with characteristic insight, said that the first step was to explore whether binocular neurons had properties that would support stereopsis - selective facilitation for precisely aligned stimuli in the two eyes and variation in optimum retinal disparity. Armed with embarrassingly primitive equipment, I was recording from V1 neurons by October 1965. But early in November, Horace came back from a symposium at Caltech with the shocking news that Peter Bishop's lab in Sydney was also looking at binocularity in V1. To try to reduce competition, Horace invited Jack Pettigrew, a medical student who was working with Bishop, to visit Berkeley in the summer of 1966. Despite the distractions of political unrest, Flower Power and the call of the outdoors, within 2 months we had the evidence for both requirements for a neural mechanism of stereopsis. We published in 1967, followed quickly by papers from Bishop's lab, confirming and extending the findings. The discovery that single neurons could encode the third dimension of space energised the debate about the representation of ‘trigger features’, stimulated the study of stereopsis, and raised important questions about the role of early experience in determining the properties of visual neurons.