American neuroscientist John O’Keefe and Norwegian scientists May-Britt and Edvard Moser won the Physiology Nobel Prize in 2014 for the discovery of the neuron navigation system.
The researchers have identified two groups of neurons that are responsible for our orientation in space. Although the brain needs two groups of neurons to determine where an individual is located and which direction he is moving towards, the functions of these neuron groups differ significantly.
It has been found that the neurons of one group get activated in response to the changing properties of the landscape. These cells react to a particular element in the environment by changing their activities when an individual moves from one point in space to another. These neurons, named the place cells, linked in patterns, actually create maps of the landscape as they perceive space. The brain acts as if it watches a movie, every frame of which represents a specific picture of the environmental change.
The other group of brain cells called the grid cells works similarly to “the inner GPS”. This system determines the location of an individual in space. The grid cells, linked together in a special pattern, give out signals when the individual alters his or her position in space. By activating these “GPS” cells, the brain arranges space into a grill-like pattern consisting of hexagonal pieces. Thus, the grid cells create a positioning system, allowing them to detect the location of the individual precisely. This group of cells marks its territory without paying attention to the landscape.
The interaction between these two types of neuron groups permits an individual to orientate himself in space. The first group of cells defines the environment while the second provides the coordinates of the location. One needs these two types of information in order to orientate himself in space. In order to better understand how the brain orients itself in space, consider this simple example. Imagine a situation in which a person receives information about a traffic jam but doesn’t know where this traffic congestion takes place. In this case, the person doesn’t have enough data to make a decision about the direction of further movement. Alternatively, a person receives information about the location of something but does not know how this “something” can have an impact on the traffic. In this case, the person in the second scenario, just as the person in the first scenario, does not have enough data to make a decision about which direction to move. One needs both data about the change and the coordinates of this change to make a decision on the direction of their further movement.
The scientists have conducted experiments in mice to demonstrate the above and now think that humans have similar groups of cells that allow them to orientate themselves in space.
Svetlana Stroganova, Nikolai Shmelev