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The GPS in our brain

The 2014 Nobel Prize in Physiology or Medicine has been assigned to John O'Keefe, May-Britt and Edvard Moser

October 2014

IMA Lab - 2014 Nobel Prize in Physiology or Medicine

How do we know where we are? How can we find the route from one place to another? And how can we store this information in such a way that we can immediately find the same route the next time we want to go to the same place? Between them, this year’s Nobel Laureates have made discoveries that add up to an understanding of a positioning system — an “inner GPS” in the brain — that makes it possible to orient ourselves in space, demonstrating a precise cellular basis for this higher cognitive function.

In 1971, John O´Keefe discovered the first component of this positioning system. He noticed that a type of nerve cell in an area of the brain called the hippocampus was always activated when a rat was positioned at a certain place in a room. Other nerve cells were activated when the rat was positioned at other places. O´Keefe concluded that these “place cells” formed a kind of map of the room.

More than three decades later, in 2005, husband and wife May‐Britt and Edvard Moser discovered another key component of the brain’s positioning system. They identified another type of nerve cell, which they called “grid cells”, which generate a coordinate system and allow for precise positioning and pathfinding. Their subsequent research showed how the “place cells” and “grid cells” working together make it possible to determine position and to navigate.

The discoveries of John O´Keefe, May‐Britt Moser and Edvard Moser have solved a problem that has occupied philosophers and scientists for centuries: how does the brain create a map of the space surrounding us and how can we navigate our way through a complex environment?

The sense of place and the ability to navigate are truly fundamental to our existence. Our sense of place gives a perception of position in the environment. During navigation, it is interlinked with a sense of distance that is based on motion and knowledge of previous positions.

After John O´Keefe's experiments with rats demonstrated  that the hippocampus generates numerous maps that can be stored and used, May‐Britt and Edvard Moser discovered an astonishing pattern of activity in a nearby part of the brain called the entorhinal cortex.

Here, certain cells were activated when the rat passed multiple locations arranged in a hexagonal grid. Each of these cells was activated in a unique spatial pattern and collectively these “grid cells” were seen to constitute a coordinate system that allows for spatial navigation. Together with other cells of the entorhinal cortex that recognize the direction of the head and the border of the room, they form circuits with the place cells in the hippocampus. This complex of circuitry constitutes a comprehensive positioning system, an inner GPS, inside the brain.

Recent investigations with brain imaging techniques, as well as studies of patients undergoing neurosurgery, have provided evidence that place cells and grid cells exist also in humans.

Grid cells and place cells offer one of the few bridges available to neuroscientists linking the cellular level to the cognitive level, as they help explain how individual brain cells help us navigate, remember the past and imagine the future.

The discovery of the brain’s positioning system represents a paradigm shift in our understanding of how ensembles of specialized cells work together to execute higher cognitive functions. It has opened up new avenues for understanding other cognitive processes, such as memory, thinking and planning.

The three professors awarded the Nobel Proze are: John O’Keefe, 75, of University College London, May-Britt Moser, 51, and Edvard Moser, 52, of the Norwegian University of Science and Technology in Trondheim.

 

 

 

References:

http://www.bbc.com/news/health-29504761

http://www.ntnu.edu/kavli