"We are interested in how space is mapped in the brain. In doing so, we used rats and their appetite for chocolate." That is how May-Britt and Edvard Moser described their work in an interview with Deutsche Welle. Chocolate is a reward for the rats and they always receive their treats at the end of specific tests.

Rats are important for the research of the two Norwegians - they have to find their way around in a specified, confined space, while the researchers look at their brain activity.

Grid cells give orientation

In 2005, the couple found special brain cells, so called "grid cells". Those cells form an imaginary hexagonal coordinate system - a grid - in the brain. The grid looks similar to tiles in a bathroom, Edvard Moser explains: "It is thought that these are part of an internal map that is based on our own movement, so that these cells signal the distances we move and the directions we take".

To measure this, the Mosers used tiny electrodes, located between the nerve cells of the rats' brain. "Then we picked up the electric signals of the cells," Moser says.

Practically speaking, it means the rat received an implant in the brain, with cables coming out of its head that were linked to a computer. That way, the researchers were able to receive and measure impulses coming out of the rat's brain. They were also able to see what happens in the brain, when the rat concluded certain tasks.

The imaginary map is stored within thousands of cells inside the brain of the rat. Whenever the animal returned to a place it had been before, the map was reactivated, thereby enabling orientation.

Rats and mice are very well suited for such experiments, Moser says. "They depend on finding their way in nature, so their navigational skills and their mapping skills are very well developed, and for that reason, we can learn a lot from studying them. "

Cooperation among many cells

Apart from these "grid cells" other cells are essential for orientation - for example so-called "border cells", which the Norwegian researchers have also found. These cells become active, when the rat approaches an obstacle, like a wall for example.

The "border cells", however, do enter into communication with so called "directional cells." Those serve as a compass and send out signals whenever the mouse turns its head in a specific direction. All those cells are building blocks for so called "place cells" - the general orientation cells that John O' Keethe, who shares the 2014 Nobel Prize for Medicine with the Mosers, had already discovered in 1971.

These are located in the hippocampus, the part of the brain, which is essential for remembering things. And there are probably many more cells to be discovered: "There is probably yet another one that tells us about the speed we are moving in space, So, I don't think we have seen the end yet. There are many, many functionally specialized types of cells", Moser believes.

New approaches to understanding Alzheimer's?

The findings of the Moser couple enable the measuring of brain-activity. Recent research has also shown that humans have similar grid cells. The research could potentially help research into Alzheimer's, as the disease tends to start with patients feeling utterly disorientated.

What is knwon is that the area of the brain the Mosers researched, is identical with the area of the brain that is affected in Alzheimer's patients. "So, quite often, if you scan brains with Alzheimer's disease you can see that there are changes in the brain area which take place before the patient has got any diagnosis."

It stands to reason to assume that this has something to do with the fact that most Alzheimer's patients lose their sense of direction first. "We are trying to understand the principles of how the brain is working, and when that is known we will probably not only be able to deal with Alzheimer's disease but a wide range of neurological and psychiatric diseases because when we know how the brain works on a more general sense then we can also treat all of these conditions."

Researchers with a passion

The 51-year-old May-Britt and 52-year-old Edvard Moser have been researching brain activity ever since their studies at the university of Oslo. They have been working with their research teams in Trondheim since 1996, where they founded the "Center for the Biology of Memory" in 2002. In 2007, it merged into the Kavli-Institute for Systems Neuroscience.

In both institutes, research focuses on the brain of animals and humans. "It is like looking into ourselves. It is scary and fascinating at the same time. For me personally, it is more fascinating. You never stop being amazed how clever this system is."