Place cells in the hippocampus fire when we are in a certain position — this discovery by John O'Keefe, May-Britt Moser and Edvard Moser brought them the Nobel Prize in Medicine in 2014. Based on which place cell fires, scientists can determine were a rat is. Neuroscientists are now able to tell where a rat will go next, just from observing which neuron fires in a task that tests rats' reference memory.