image: Exploring a new environment. In rat pups, place cells in the hippocampus fire whenever the animal traverses a particular location within the environment; direction cells fire whenever the animal’s head faces in a certain direction relative to its environment; grid cells fire at repeated locations such that these locations for a particular grid cell form the vertices of a regular, repeating grid covering the environment. The direction and place cells are present when pups make their first such exploration; when grid cells appear is disputed. This image relates to a Perspective that appeared in the June 18, 2010, issue of Science, published by AAAS. The Perspective, by Dr. L. Palmer of the University of California, Irvine in Irvine, Calif., and colleagues, is titled, "A Kantian View of Space." view more
Credit: Image: Y. Greenman/<i>Science</i> © 2010 AAAS