Ears Too Big? It's All in Your Head

By Constance Holden
ScienceNOW Daily News
3 December 2007
People with body dysmorphic disorder (BDD) hate the way they look.
Even though they are as normal in appearance as anyone else, they are
obsessed with features such as their skin, their noses, and their
hair, which--to them--never look right. Now, the first brain-imaging
study of BDD patients shows that the condition is not just an
emotional problem. Rather, their brains are presenting them with
skewed images of themselves.

Psychiatrist James Feusner and colleagues at the University of
California, Los Angeles, asked BDD subjects and controls to scrutinize
images of faces while their brains were being scanned by functional
magnetic resonance imaging. Each face was presented in three versions:
One was an unaltered photograph; one included only low-spatial-
frequency information, resulting in a blurred image that yielded just
a general impression of the face; and the third contained only high-
frequency information, which exaggerated the lines of the face (see
picture).

Previous research has shown that different neural pathways process
high- and low-frequency information. When the image is blurry, the
normal brain analyzes the face as a whole, whereas with high-frequency
data, it zeroes in on details. The scientists found that the control
subjects used a more holistic, right-brain strategy for the unaltered
face and the low-frequency one. They only moved to the high-detail
strategy for the high-detail face. In the BDD group, however, subjects
failed to look at the figure as a whole, instead using left-brain
channels that dwell on details for all three faces.

Feusner says the people with BDD don't have defective vision, as shown
by the fact that there were no differences between the two groups in
the activity of the occipital lobe, the brain's primary visual area.
The differences show up in their "extended visual processing network,"
indicating that perceptions get twisted beneath the level of emotion
or conscious thought, says Feusner, whose report appears in the
December issue of the Archives of General Psychiatry.

Sanjaya Saxena, a psychiatrist at the University of California, San
Diego, says that as a rule, psychiatrists have assumed that the
distorted perceptions of people with BDD only related to how they view
themselves. This study indicates that these distortions go deeper to
include perceptions of others, he says. That helps explain why the
disorder seems so "ingrained," Saxena says, and suggests that in
addition to measures to reduce anxiety and depression, people with BDD
might benefit from behavioral therapy aimed at "retraining" their
visual processing. Feusner's team is now enrolling patients for the
next stage of the study: seeing how patients react to altered and
unaltered pictures of themselves.

Source: Science
http://sciencenow.sciencemag.org/cgi/content/full/2007/1203/2?etoc