American-British scientist John O’Keefe and Norwegians May-Britt and Edvard Moser won the 2014 Nobel Prize for medicine on Monday for discovering the brain’s internal positioning system, an “inner GPS” that makes it possible to orient ourselves in space, demonstrating a cellular basis for higher cognitive function. Their research explains how the brain creates a map of the space surrounding us and how can we navigate our way through a complex environment.
Knowledge about the brain’s positioning system can help understanding of what causes loss of spatial awareness in stroke patients or those with devastating brain diseases like dementia, of which Alzheimer’s is the most common form and which affects 44 million people worldwide.
John O´Keefe discovered the first component of the positioning system in 1971 when he found that a type of nerve cell in the hippocampus was always activated when a rat arrived at a certain place in a room (Figure A). Seeing that other nerve cells were activated when the rat was in other positions, O´Keefe concluded that these “place cells” formed a map of the room. O’Keefe concluded that the hippocampus generates numerous maps and the memory of an environment can be stored.
Thirty years later, May-Britt and Edvard Moser discovered another key component of the brain’s positioning system. In 2005, they identified cells in the entorhinal cortex region in brains of rats, which function as a navigation system. These so-called “grid cells,” (Figure B) they discovered, are constantly working to create a map of the outside world and are responsible for animals’ knowing where they are, where they have been, and where they are going. The finding explains how the brain works, but does not have immediate implications for new medicines since it does not set out a mechanism of action.
What it means for the human brain
Scientists have determined through brain imaging techniques that “place” and “grid” cells exist in human brains, which has implications for diseases such as Alzheimer’s. In patients with Alzheimer’s, the hippocampus and entorhinal cortex – the parts of the brain where grid and place cells are located -- are frequently affected at an early stage, and these individuals often lose their way and cannot recognize the environment.
Researchers hope the knowledge gained from the discovery will eventually lead to understanding and ultimately preventing spatial memory loss that affects people with Alzheimer’s.