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Raymond Michael ‘Mike’ Gaze FRS (22 June 1927—11 September 2012) was a British neuroscientist who pioneered electrophysiological recording techniques for investigating how nerve connections form, specifically with a focus on the eye-brain connection. He showed, for the first time, that the nerve connections formed, during both regeneration and normal development, are plastic. Even during normal development retinal fibres are continually changing their connections. Mike was elected Fellow of the Royal Society of Edinburgh in 1964, of the Royal Society (London) in 1972.

Mike was Deputy Director of The National Institute for Medical Research (the forerunner to the Francis Crick Institute) from 1977 to 1983. In 1986 he was made an Honorary Professor at the University of Edinburgh, where he had served within the physiology department at different stages of his career. He served as Editor for the journal Development (then called the Journal of Embryology and Experimental Morphology) from 1976 to 1988.

Early life
Mike was born in England and moved to Scotland at age 12. He was educated mainly privately at home and aged 16 years entered Edinburgh College of Surgeons, qualifying in medicine in 1949. Admitted to Balliol College, Oxford on Schorstein scholarship to study animal physiology. One year later began doctoral work supervised by George Gordon. Awarded doctorate (DPhil) in 1953. Mike spent two years military service as medical officer.

Scientific career
In 1955 appointed Lecturer in Physiology at the University of Edinburgh and was made Reader in Physiology in 1966. In 1970 he accepted the invitation to set up and lead a new Division in Developmental Biology at The National Institute for Medical Research in London. In 1984 he returned to the University of Edinburgh to lead a Medical Research Council unit on Neural Development and Regeneration. He retired in 1992.

Neural plasticity and systems matching
Mike learned the technique of electrophysiological recording from his doctoral supervisor, George Gordon. At Edinburgh the departmental head, David Whitteridge, introduced Mike to the work of Roger Sperry. Sperry had cut the optic nerve in frogs, rotated the eye through 180 degrees, and waited until the nerve grew back. When vision was restored the animals behaved as though, through the rotated eye, they saw the world upside down. Mike repeated Sperry's experiments but used the technique of electrophysiological recording to establish the exact pattern of functional connections between eye and brain. In so doing he was the first to use this technique in the context of nerve regeneration, and later in the context of nerve development. Mike established the anatomical basis for Sperry's behavioural observations and confirmed Sperry's anatomical assumptions.

Sperry had put forward the theory of neuronal specificity (now generally known as the chemoaffinity theory) to account for his results. According to this theory the rule that determines which part of the retina connects with which part of the tectum (one of the visual areas of the brain) is precise and rigid, and does not involve any interaction between the retinal nerve fibres themselves. In 1963, Mike, in collaboration with György Székely and Marcus Jacobson, reported the first experiment that challenged Sperry's theory. Using a technique pioneered by Székely they examined the connections of the retinal nerves to the tectum in eyes formed, at embryological stages, by putting together the same half eye (e.g. the front - nasal - half) from two different eyes. They found that the nerves from each half eye spread to cover the whole of the tectum.

In further experiments Mike and his colleagues removed parts of the tectum, or parts of the retina, and examined the regenerated connections between retina and tectum. If they waited long enough the whole of (what remained of) the retina covered, in precise order, the whole of (what remained of) the tectum.

The retinal cells of the frog connect with the tectum during development well before either the retina or the tectum have finished growing. Mike and his colleagues showed that during normal development these connections must be 'plastic' - that is the connections made by the retinal fibres are continually sliding, forming and breaking connections on the tectum. In 1972 ‘this idea was quite revolutionary’. Mike and colleagues wrote: ‘What seems to be happening is that the two neural populations link up under the control of factors which appear to be operating on a system-to-system rather than a cell-to-cell basis. During development the connexions of a given retinal ganglion cell change in an ordered fashion.’ Mike coined the term 'systems matching' to describe this process.

In their work with compound eyes Mike and colleagues noted, in passing, that the ipsilateral projection from the normal eye was frequently abnormal. Mike’s doctoral student, Mike Keating advanced a possible explanation. He wrote: ‘The ipsilateral retinotectal projection is produced, not by innate specification processes, but by a linkage of the two points on the two tecta that are receiving similar spatiotemporal excitation patterns. Thus specific neuronal connexions may be produced by a functional interaction between the environment and the nervous system.’ This was, at the time, a radical hypothesis. Over the following years Mike Gaze and colleagues examined this hypothesis in various situations. In all situations the ipsilateral projection fitted the functional hypothesis. The importance of functional interaction had been emphasized by Hebb in the context of learning. It had been shown to be significant in the preservation of the normal binocularity of cells in the cat’s visual cortex. What Mike and his colleagues showed for the first time was that the formation of new, precise arrangements of nerve fibres could result from the functional interaction between the two eyes. Since the degree of binocular overlap changes as the eyes move during late larval stages and at metamorphosis, the functionally determined connections between the tecta also change: these connections, like the retino-tectal connections, must be ‘sliding’ during normal development.

Personal life
Mike married Robinetta Mary Armfelt (known as Robin) in 1957. Their daughter, Harriet, was born in 1958 and twins, Hannah and Julian, were born in 1959. In addition to family life and his career Mike was a keen flautist and enjoyed walking particularly in his beloved Scotland. After retirement he began writing a book on land ownership in Scotland but sadly he developed dementia. Robin looked after him at home until this became impossible. He died at Camilla House Nursing Home in Edinburgh aged 85 years old.

Recognition

 * 1949 Schorstien scholarship, Balliol College, Oxford
 * 1956 The Rolleston Memorial Prize for original research, University of Oxford
 * 1967 Committee member of The Physiological Society
 * 1962-1966 Alan Johnston, Lawrence and Moseley Research Fellowship, The Royal Society
 * 1964 Elected Fellow of the Royal Society of Edinburgh
 * 1972 Elected Fellow of the Royal Society (London).
 * 1976-1988 Editor of Journal of Embryology and Experimental Morphology [now called Development]
 * 1977-1983 Deputy Director of the National Institute for Medical Research
 * 1986 Honorary Professor Edinburgh University
 * 1988 Rand Fellow, Marine Biological Laboratory, Woods Hole, USA