Feeling fat in the festive season? It's all in your mind

November 28, 2005

Feeling thin or fat is an illusion constructed in the brain, according to a new study published in the journal Public Library of Science Biology. The collaborative study led by UCL (University College London) used a trick called the Pinocchio illusion to scan people's brains while they experienced the sensation that their waists were shrinking. The study reveals which parts of the brain are involved in body image and may shed some light on anorexia and body dysmorphic disorder, where sufferers are overly concerned by a small or imagined defect in their body, and frequently overestimate or underestimate their actual body size.

The study, led by Dr Henrik Ehrsson of the UCL Institute of Neurology, used the Pinocchio illusion in combination with functional magnetic resonance imaging to study volunteers' brains. For each volunteer, a vibrating device was placed on their wrist to stimulate the tendon and create the sensation that the joint was flexing, even though it remained stationary. With their hand touching their waist, volunteers felt their wrists bending into their body, creating the illusion that their waists were shrinking.

During the tendon exercise, all 17 participants felt that their waist had shrunk by up to 28 per cent. The researchers found high levels of activity in the posterior parietal cortex, an area of the brain that integrates sensory information from different parts of the body. Volunteers who reported the strongest shrinking sensation also showed the strongest activity in this area of the brain.

Dr Henrik Ehrsson, of the UCL Institute of Neurology, says: "We process information about our body size every day, such as feeling thin or fat when we put our clothes on in the morning, or when walking through a narrow doorway or ducking under a low ceiling. However, unlike more elementary bodily senses such as limb movement, touch and pain, there are no specialized receptors in the body that send information to the brain about the size and shape of body parts. Instead, the brain appears to create a map of the body by integrating signals from the relevant body parts such as skin, joints and muscles, along with visual cues.

"Other studies have shown that people with injuries in the parietal cortex area of the brain experience the feeling that the size and shape of their body parts have changed. People who suffer from migraine with aura can sometimes experience a phenomenon called the 'Alice in Wonderland syndrome', where they feel that various body parts are shrinking. This could also be linked to the same region of the brain. In addition, people with anorexia and body dysmorphic disorder who have problems with judging the size of their body might similarily have a distorted representation of their body image in the parietal cortex. These are areas which would be worth exploring in future research, to establish whether this region of the brain is involved in anorexia and the rare but peculiar shrinking symptoms of some migraines."
-end-


University College London

Related Brain Articles from Brightsurf:

Glioblastoma nanomedicine crosses into brain in mice, eradicates recurring brain cancer
A new synthetic protein nanoparticle capable of slipping past the nearly impermeable blood-brain barrier in mice could deliver cancer-killing drugs directly to malignant brain tumors, new research from the University of Michigan shows.

Children with asymptomatic brain bleeds as newborns show normal brain development at age 2
A study by UNC researchers finds that neurodevelopmental scores and gray matter volumes at age two years did not differ between children who had MRI-confirmed asymptomatic subdural hemorrhages when they were neonates, compared to children with no history of subdural hemorrhage.

New model of human brain 'conversations' could inform research on brain disease, cognition
A team of Indiana University neuroscientists has built a new model of human brain networks that sheds light on how the brain functions.

Human brain size gene triggers bigger brain in monkeys
Dresden and Japanese researchers show that a human-specific gene causes a larger neocortex in the common marmoset, a non-human primate.

Unique insight into development of the human brain: Model of the early embryonic brain
Stem cell researchers from the University of Copenhagen have designed a model of an early embryonic brain.

An optical brain-to-brain interface supports information exchange for locomotion control
Chinese researchers established an optical BtBI that supports rapid information transmission for precise locomotion control, thus providing a proof-of-principle demonstration of fast BtBI for real-time behavioral control.

Transplanting human nerve cells into a mouse brain reveals how they wire into brain circuits
A team of researchers led by Pierre Vanderhaeghen and Vincent Bonin (VIB-KU Leuven, Université libre de Bruxelles and NERF) showed how human nerve cells can develop at their own pace, and form highly precise connections with the surrounding mouse brain cells.

Brain scans reveal how the human brain compensates when one hemisphere is removed
Researchers studying six adults who had one of their brain hemispheres removed during childhood to reduce epileptic seizures found that the remaining half of the brain formed unusually strong connections between different functional brain networks, which potentially help the body to function as if the brain were intact.

Alcohol byproduct contributes to brain chemistry changes in specific brain regions
Study of mouse models provides clear implications for new targets to treat alcohol use disorder and fetal alcohol syndrome.

Scientists predict the areas of the brain to stimulate transitions between different brain states
Using a computer model of the brain, Gustavo Deco, director of the Center for Brain and Cognition, and Josephine Cruzat, a member of his team, together with a group of international collaborators, have developed an innovative method published in Proceedings of the National Academy of Sciences on Sept.

Read More: Brain News and Brain Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.