Scientists develop brain prosthesis for rats: "Scientists do not know exactly how the hippocampus works. So the Californian team simply copied its behaviour. Slices of rat hippocampus were stimulated with electrical signals millions of times, until scientists could be sure which input produced a corresponding output. Putting the information from each slide together, the researchers were able to devise a mathematical model of a whole hippocampus. The model was then programmed on to a chip".