People use geometrical relationships to orient themselves

The brain has a complex system for keeping track of which direction you are facing as you move about that makes remembering how to get from one place to another possible, a new study has found.
The findings by researchers from the University of Pennsylvania provide a neurological basis for something that psychologists have long observed about navigational behaviour: people use geometrical relationships to orient themselves.
The study adds new dimensions to our understanding of spatial memory and how it helps us to build memories of events, researchers said.
To test how the brain makes these inferences, the researchers designed an experiment in which they introduced participants to a virtual environment, a set of four museums in a park, and had the participants memorise the location of the everyday objects on display in those museums.

They then scanned their brains while asking them to recall the spatial relationships between those objects, such as whether the bicycle was to the left or the right of the cake.
In the scans, using a technique that measures blood flow to different regions of the brain known as fMRI, researchers focused on a region known as the retrosplenial complex.

People who have severe injuries to this region are able to recognise landmarks in their environments but are unable to recall how to get from one to another, suggesting that it plays a specific role in the type of memory used in navigation and orientation.

There are three ways the retrosplenial complex could conceivably encode this type of information and serve as part of a mental compass.
One way would be a "global" system, in which the brain tracks the absolute direction one is facing regardless of visual cues in the environment.
An "idiosyncratic" system, in which the brain keeps tracks of direction for each environment independently, was another possibility, researchers said.
Finally, they considered a "geometric" system that is based on more generalised relationships between features in an environment.
The study was published in the journal Nature Neuroscience.