The Neuroscience of 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. If you are having these symptoms Long Island neurosurgeons can help you understand why, and can give you proper treatment.
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. The inpatient eating disorder treatment 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?
Riva, Guiseppe (2010). Neuroscience and Eating Disorders:
The role of the medial-temporal lobe Nature Proceedings
Mike Sandifer
March 15, 2010 @ 11:54 am
I think some of the possible neurophysiological elements involving body image dysphoria as related to eating disorders are interesting. However, the purely physiological depiction of the role of stress in the etiology of eating disorders suffers from a lack of attention given to the learning, behavioral economics, and evolutionary contexts.
Specifically, the omission of activity anorexia-related food restricted triggers of decreased appetite as adjunctive behaviors(1), and the lack of rigorous definition of chronic stress(2), leave the subject of eating disorder etiologies incomplete.
With respect to the role of chronic stress, it causes lower moods, reflecting a lower net rate of intake of reinforcement, or resources necessary to pass genes optimally. Food restriction thus causes lower moods while specifically triggering decreased appetite and hyperactivity, especially with respect to physical exercise.
Lower moods lead to increased risk aversion in most, with any fears associated with negative perceptions of physical attractiveness exacerbated.
I consider that the goal of this post may exclude a comprehensive treatment of eating disorder etiologies and mechanisms, but I thought these additional dimensions worth mentioning.
1. Epling, Frank W. and Pierce, David W.
Activity-based anorexia: A biobehavioral perspective.
International Journal of Eating Disorders, VL: 7, NO: 4, PG: 475-485, YR: 1988.
2. http://quantimind.blogspot.com/2010/02/mood-this-time-with-feeling-simpler.html
Kim
March 17, 2010 @ 7:23 pm
I think that Anorexia Nervosa can have tragic results. It’s difficult for people to deal with their body image sometimes. That’s why I’m excited for the new book “Looking Good Naked” by David Desjardins and Helene Dumais. I think this book could help people improve their body image through a healthy lifestyle, rather than starvation. I hope that it can help people who are struggling with eating disorders to discover their true beauty.
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March 19, 2010 @ 2:49 pm
Anorexia is not really about losing weight, eating or not, exercising or not, it is about self-esteem, it is about how you feel about yourself.
Mike Sandifer
March 20, 2010 @ 1:55 pm
You can talk about negative body image all you want, but the food restriction and certain exercise patterns are what trigger anorexia nervosa. This is seen in humans and other species as well.
In fact, in the lab, anorexia can reliably be triggered in rats via food restriction and wheel running. Do the rats have negative body images?
That suggestion that negative body images directly cause anorexia are absurd. Rather, they sometimes lead to food restriction, that combined with certain exercise patterns trigger an adjunctive relationship between the two.
Dr Shock
March 21, 2010 @ 1:07 pm
Can a rat have anorexia nervosa? Anyway it’s presented as part of the psychophysiology and certainly not the only plausible answer as to why someone will get anorexia. As with most psychiatric disorders the reality is much more complicated. Thought it a very interesting and creative look on matters as complicated as anorexia, thnx and take care,
Dr Shock
Neuroscience and body image - with eating disorders (I'm looking for research . . . )
July 2, 2010 @ 4:53 am
[…] I was reading up on the neuroscience of anorexia – found this article that explains it quite well: The Neuroscience of Anorexia Nervosa | Dr Shock MD PhD And I'm now looking for an equal study/article that discusses this altered body-perception when it […]