| Mariette Le Roux |
PARIS (AFP) – Generations of scientists have pored over a seemingly basic but ultimately complex skill: how are humans able to find their way from one spot to another?
Little by little, the fog of mystery is beginning to dissipate, thanks to work revealing the key areas in the brain that enable us to orientate ourselves and navigate.
On Monday, the 2014 Nobel Prize for Medicine went to a trio of scientists who identified the brain cells essential to this task.
In the early 1970s, John O’Keefe, a British-American neuroscientist, discovered “place” cells that are triggered when the brain perceives it is in a specific location.
More than three decades later, a Norwegian couple, May-Britt and Edvard Moser, found “grid” cells, which like step-points on a map enable the mind to work out a path to a destination.
Together, the two types of cells form inter-connected networks without which we would not know where we were or be able to find our way.
The research may one day help treat neurodegenerative conditions that leave people unable to manage even the most basic tasks.
The breakthrough came in 1971, when O’Keefe observed that specific neurons in the hippocampus area, which is linked to memory, fired whenever a lab rat, with electrodes inserted in the brain, reached a particular spot in a room.
When the rodent moved to another area, different cells lit up – each cell was thus associated with a specific location.
This pattern of cell activity, observed with the help of electrodes in the brain, created a sort of brain map of the environment, O’Keefe discovered.
“I remember how great was the scoffing in the early 1970s when John first described ‘place cells’,” said John Stein, emeritus professor of Physiology at Oxford University.
“‘Bound to be an artefact’, ‘He clearly underestimates rats’ sense of smell’ were typical reactions. Now, like so many ideas that were at first highly controversial, people say, ‘Well that’s obvious’!”
O’Keefe’s work in turn inspired the Moser husband-and-wife team, for whom he became a mentor.
In 2005, they discovered a new type of cell in an area of the brain next to the hippocampus called the entorhinal cortex.
These cells fired in an astonishing hexagonal pattern as the rat passed multiple locations enticed by chocolate treats, and the couple concluded that they functioned as a coordinate system for spatial navigation.
“Place” and “grid” cells have since been found in mammals other than rats, and evidence points to them also existing in humans.