The Neuroscience of Anorexia Nervosa

anorexia nervosa

One of the most striking features of those suffering from anorexia nervosa is their perception of their bodies. You can put them in front of a mirror and they will still tell you they’re to fat when in fact they’re skinny. A recent publication in Nature Proceedings has an explanation.

This explanation is based on the fact that our spatial experience is based on the integration of two different kinds of input, two different sensory inputs within two reference frames. These two reference frames are the egocentric frame and the allocentric frame.
With the allocentric frame you can “see yourself engaged in the event as an observer would”, it’s the observer mode, you can see your self in the situation. This allocentric representation involves long term spatial memory mostly located in the hippocampus and the surrounding medial temporal lobes of the brain.

The egocentric frame is about the body being the reference of the first person experience. Seeing the event from his or her perspective as in normal perception, the field mode. So you’re not looking at your self and seeing your self in a certain situation but your looking from within your self to the outside world. These egocentric representations are modeled with the short term spatial memory located mostly in the precuneus of the brain.

These two frames have to integrate the information, the knowledge from the long term memory has to be updated with the egocentric representation that can influence the information present in long term memory. That’s needed to update the body dimensions and motor patterns. If this doesn’t happen the subject is locked to the older representation of the body, this will not be renewed, updated, the subject is locked to the old representation.

If, for some reasons, this process is impaired, the egocentric sensory inputs are no more able to update the contents of the allocentric representation of the body: the subject is locked to it. This is what apparently happens in eating disorders (ED)

The parts of the brain involved with the locking process are the medial temporal lobe, connections between hippocampus and amygdala. Stress can provoke hippoacampal damage. As suggested by some authors stress is often related to the onset of eating disorders and chronic stress is associated with the persistence of eating disorders. Neuroimaging showed some evidence for impairment of medial temporal lobe functioning in eating disorders.

Overall eating disorders are influenced by several possible factors as depicted in the graphic below. Nevertheless this theory is an interesting one and to my opinion a very promising one from a scientific point of view, what do you think?

neuroscience of eating disorders
Riva, Guiseppe (2010). Neuroscience and Eating Disorders:
The role of the medial-temporal lobe Nature Proceedings