How do we experience our environment?
Questions about place and navigation have engaged philosophers and scientists for a long time. When Edward Tolman examined rats moving through labyrinths, he found that they could learn how to navigate, and proposed that a “cognitive map” formed in the brain allowed them to find their way.
But questions still lingered – how would such a map be represented in the brain?
John O´Keefe and the place in space
John O´Keefe, University College, London, United Kingdom, was fascinated by the problem of how the brain controls behaviour and decided, in the late 1960s, to attack this question with neurophysiological methods. When recording signals from individual nerve cells in a part of the brain called the hippocampus, in rats moving freely in a room.
O’Keefe concluded that the hippocampus generates numerous maps, represented by the collective activity of place cells that are activated in different environments. Therefore, the memory of an environment can be stored as a specific combination of place cell activities in the hippocampus.
May-Britt and Edvard Moser find the coordinates
May-Britt and Edvard Moser (Centre for Neural Computation, Trondheim, Norway and Kavli Institute for Systems Neuroscience, Trondheim, Norway, 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.
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.Leave a reply →