Campbell FW & Green DG. Optical and Retinal Factors Affecting Visual

CC/NUMBER 45

This Week’s Citation Classic ® NOVEMBER 5, Campbell F W & Green D G. Optical and retinal factors affecting visual resolution. J. Phvsiol. —London (81:576-93. 1965: and Campbell F W & Robson J G. Application of Fourier analysis to the visibility of gratings. J. Phvsiol. —London 197:551-66, 1968. [Physiological Laboralory. University of Cambridge. England] These papers measure the optical transfer tunction of Co orientation. The idea that these same neurones the optics of the eye and the contrast sensitivit func- might be also selectively sensitive to spatial fre- tion of the retina-brain. The second one gave rise to quency provided a mathematical tool to replace a the concept that the visual cortex of man had neuth- verbal vacuum about how we see objects. Percep- rones tuned to spatial frequency (size). [The Sc> tion psychologists quickly adopted this quantitative indicates that these papers have been cited in more approach and abandoned their verbal approach. than 705 and 600 publications. respective)y.l Christina Enroth-Cugell and Robson, working at Northwestern University, found that cat ganglion -~ . ~ 2 cells could be divided into two types. The X nest- Probing the Human Visual System rone behaved linearly and the Y very nonlinearly.At Fergus W. Campbell that time everyone assumed that the visual system Physiological Laboratory was very nonlinear, and they had great difficulty f University of Cambridge with the referees! Cambridge CB2 3EG Dan Green, from the University of Michigan, vis- England ited me in 1963 when I had become intrigued with the potential use of the laser in vision research. We June 4, 1990 used it to bypass the optics of the eye and were able When I joined, in 1952, the Physiological Labora- to establish the transmission properties of the tory in Cambridge, Edgar Adrian, Alan Hodgkin, human retina when it was operating well at high and Andrew Huxley were the dominant scientists luminance levels. It turned out that the optics of the and all had Nobel Prizes by 1963. The research eye were well matched to the transmission proper- tradition was a ‘~stringand sealing wax” affair and ties of the retina. At that time most textbooks main- most of the apparatus was handmade by each re- tained that the resolving power ofthe eye wassolely search worker. I once asked Adrian how he dealt due to the optics. This paper is also often quoted for with the exponentially increasing research litera- the methodology of using a laser in visual research. ture and he replied, 9t is only necessary to read the At that time lasers were thought to be very danger- first paper which proposes the problem and the last ous to look at; 25 years later I still have not devel- paper that solves it. The ones in-between do not oped cataract! matter.” Cohn hllakemore returned from the University of Among my childhood hobbies were microscopy, California, Berkeley, to join the staff in 1967. We photography, and radio electronics; by 1955 the accidentally discovered a way of proving that the Fourier approach was becoming popular for the human visual cortex had neurones that were tuned study of optical, television, and photographic sys- not only3 to orientation, but also to spatial fre- tems, and I began to wonder whether this new quency. Although this was known to be occurring approach might help us to understand how the in the cat cortex, there was no positive evidence human visual system operated. In 1957 John G. that the human cortex was similarly organised. This Robson took over my tiny laboratory to undertake led to a detailed examination of the cortical neu- his PhD research on “muscle tremor.” After several rones in the monkey (see the review by R. De Valois years of acrimonious argument, we ultimately pub- and K. De Valois4 for subsequent developments, lished the above paper, which neither of us had set induding their own very substantial contributions). out to produce. By 1962 David Hubel and Torsten This is still a very active field of research, and it is Nils ‘Mesel had established the startling discovery with regret that I cannot find Lord Adrian’s “last that neurones in the cat’s visual cortex were tuned paper.”

1. Ifubel D H & Wi~seIT N. Receptive fields, binocular interaction and functiosal architecture in the cat’s visual cortex. I. PFtysioL—London 160:106-54, 1962. (Cited 2,590 times.) (See also: Hubel OH. Citation Classic. Current Contents/Life Sciences 28(191:23. 13 May 1985. I 2. Enroth-CugeIl C & Robson J G. The contrast sensitivity of retinal ganglion cells of the cat. J. Physiol —London 187:517-52. 1966. (Cited 1,065 times.> lSee also: Robson J G. Citation Classic. Current Contents/Life Sciences 29t8):l8, 24Fehrstary 1986.] 3. Blakemore C & Campbell F W. On the existence of neurones in the human visual system selectively sensitive to the orientation and size of retinal images. I. Physiol,_—London 203:237-60. 1969. (Cited 660 times.) [See also: Campbell F W. Citation Classic. Current Contents/Life Sciences 28(45):24, II November 1985.) 4. De Valuis IC L & Dr Valois K K. Spatial cision. Oxford. England: Oxford University Press, 988. (Cited 5 times.)

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