The Young Chronicle: For Grade 3 December 5th, 2014 | Page 5

YOUNG CHRONICLE

November 28th , 2014

The Brain’s GPS!
(Continued from page 1)

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 around us and how can we navigate our way through the environment?

How do we experience our environment?
The sense of place and the ability to navigate are fundamental to our existence. The 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.

May-Britt and Edvard Moser find the coordinates
May-Britt and Edvard Moser were mapping the connections to the hippocampus in rats moving in a
room when they 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 (Figure 2). Each of these cells was activated in a unique spatial pattern and
collectively these "grid cells" 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 circuitry
constitutes a comprehensive positioning system, an inner GPS, in the brain (Figure 3).

A place for maps in the human brain
Recent investigations with brain imaging techniques, as well as studies of patients undergoing
neurosurgery, have provided evidence that place and grid cells exist also in humans. In patients with
Alzheimer's disease, the hippocampus and entorhinal cortex are frequently affected at an early
stage, and these individuals often lose their way and cannot recognize the environment. Knowledge
about the brain's positioning system may, therefore, help us understand the mechanism underpinning
the devastating spatial memory loss that affects people with this disease.
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 new avenues for understanding other cognitive processes, such as memory, thinking and
planning.