The Existential Essence of Orientation

Where am I? Where am I Going?

Those questions are at the heart of orientation, and scientists have shown that -- in rats, and presumably people -- distinct cells correspond to each type of information.

When a rat goes somewhere new, two groups of cells form within minutes: the first are related to location and are activated upon return. The second type of cell is activated according to the direction the rat is facing.

So how did this cellular compass come into being?

Using a computer model, German scientists have shown that the brain may turn visual information into a cognition map that subequently activates the production of orientation cells.

Every receptor in the eye only captures a very small section of the perceived image. When shifting the gaze just a little, the information that every single receptor transmits will be quite different than before. While sensors deliver constantly changing data, the information important for orientation varies far more slowly -- the overall impression in the example above remains almost constant. Features that vary slowly can be obtained from image data by slow feature analysis.

With their model, the scientists could show that slow feature analysis allows the emergence of what one could call a "cognitive map" from the linear sequence of visual data a rat receives when moving through a new environment. In this map, positions are coded by place cells, whereas a directional reference frame is given by head direction cells. It is only after this learning process that disparate visual impressions can activate the same set of place- or head direction cells.

One possible avenue of future explanation: would the model work the same for non-visual information? A rat could conceivably be immersed in pitch-black darkness, but something -- a block of cheese, for example
-- might provide olfactory points of reference as to the rat's spacial relationship to it. Maybe this could explain how rats do so well in sewers....

The Emergence Of A Sense Of Orientation [Press Release]

Slowness and Sparseness Lead to Place, Head-Direction, and Spatial-View Cells [PLoS Computational Biology]