Geoffrey Raisman. 28 June 1939—27 January 2017

Geoffrey Raisman was a neuroscientist whose particular love was the microanatomy and ultrastructure of the nervous system. From his anatomical studies came discoveries in synaptic plasticity, neuroendocrinology, axon regeneration, spinal cord repair and glaucoma. His studies of the anatomy of synapses after denervation led to his concept of plasticity, where synapses compete for targets and can replace those that are lost. This discovery persuaded him, against the dominant view of the time, that some repair of the damaged nervous system should be possible. His studies of the events following damage to the nervous system led to the pathway hypothesis; axon regeneration is blocked by scar tissue formed of glial cells around injuries. Finding that the newly born olfactory neurons that are created throughout life grow axons into the brain with the assistance of specialized olfactory glia, he realized that these glial cells might also assist regenerating axons to bridge the scar tissue blocking axon regeneration. Preliminary trials of this treatment in human spinal cord injuries have shown some clinical promise. He recently developed a new energy theory of glaucoma.