On the grid

ANIMALS, most of them anyway, move about. That is what the word means. But it is not much use moving around if you do not know where you are. This year’s Nobel prize for physiology or medicine, therefore, was awarded to three scientists who have helped work out how mammals do this. Between them, John O’Keefe of University College London, and May-Britt Moser and Edvard Moser of the Norwegian University of Science and Technology, in Trondheim, discovered two sets of cells, in two neighbouring parts of the brain, which tell that brain where it is.

Dr O’Keefe published his prize-winning work in 1971. He had been studying rats’ brains by recording the electrical activity of individual nerve cells in a part of the brain called the hippocampus. He found that some cells, now known as place cells, were quiet most of the time, but burst into life whenever the rat in question was in a particular part of its range—different cells being active in different places. This was the first indication that there is a specific relationship between the geography of the outside world and the geography of an animal’s brain.