Say you meet an old friend at the train station. She is standing about a metre ahead of you, and on the tracks to your right a train has just pulled into the station. Behind your friend you see a bakery. We often remember such scenes in vivid detail. But exactly how we do that by forming mental images has long been a bit of a mystery.
Many researchers liken someone’s recall of an episode from their life (episodic memory) to re-experiencing of the original event. What is unclear is how this process could be realised in the brain, at the level of single brain cells (neurons). Now our new study, published in eLife, has come up with a suggestion.
It is possible to measure the activity of single brain cells. Experiments with rodents have shown that certain cells are active whenever an animal is located at a particular spot in the environment. These so-called “place cells” therefore represent an animal’s position in a given environment.