Susumu Tonegawa was a Japanese scientist who was the sole recipient of the Nobel Prize for Physiology or Medicine in 1987 for his discovery of V(D)J recombination, the genetic mechanism which produces antibody diversity. Although he won the Nobel Prize for his work in immunology, Tonegawa was a molecular biologist by training and, following his Nobel Prize win, changed fields to neuroscience, examining the molecular, cellular and neuronal basis of memory formation and retrieval.