Posts tagged extrastriate body area
Articles and news from the latest research reports.
Patients with autism spectrum disorder are not sensitive to ‘being imitated’
A Japanese research group led by Prof Norihiro Sadato, a professor of the National Institute for Physiological Sciences (NIPS), National Institutes of Natural Sciences (NINS), has found that people with autism spectrum disorders (ASD) have decreased activity in an area in the brain critical for understanding if his/her movement was imitated by others. These results will be published in Neuroscience Research.
The research group of Norihiro Sadato, a professor of NIPS, Hirotaka Kosaka, a specially-assigned associate professor of the University of Fukui, and Toshio Munesue, a professor of Kanazawa University measured brain activity by functional magnetic resonance imaging (fMRI) when one’s movement was imitated by others. The group studied brain activity when a subject saw his/her finger movement imitated or not imitated by others. Normal subjects have increased activity in the extrastriate body area (EBA) when they are imitated compared to when they are not being imitated. The EBA is a region in the visual cortex for visual processing that responds powerfully during the perception of human body parts. On the other hand, because this kind of activity in the EBA of subjects with ASD was not observed, it shows that the EBA of subjects with ASD is not working properly when imitated.
Persons with ASD are known to have difficulty in interpersonal communication and have trouble noticing that their movement was imitated. Behavioral intervention research to alleviate ASD is proceeding and indicates that training utilizing imitation is useful. The result of the above research not only provided clues to ASD, but also can be used in the evaluation of behavioral intervention to alleviate the disorder.
(Source: eurekalert.org)
“Connection error” in the brains of anorexics
When people see pictures of bodies, a whole range of brain regions are active. This network is altered in women with anorexia nervosa. In a functional magnetic resonance imaging study, two regions that are important for the processing of body images were functionally more weakly connected in anorexic women than in healthy women. The stronger this “connection error” was, the more overweight the respondents considered themselves. “These alterations in the brain could explain why women with anorexia perceive themselves as fatter, even though they are objectively underweight” says Prof. Dr. Boris Suchan of the Institute of Cognitive Neuroscience at the Ruhr-Universität. Together with Prof. Dr. Dietrich Grönemeyer (University of Witten-Herdecke), Prof. Dr. Silja Vocks (University of Osnabrück) and other colleagues, the Bochum researchers report in the journal Behavioural Brain Research.
Anorexics misperceive their body shape
The researchers tested ten anorexic and fifteen healthy women of similar age. To start with, all the women judged on the computer which of several different silhouettes corresponded best to their own body shape. Ten control subjects who did not participate in the MRI scan answered the same question by matching a photo of the test subject to the right silhouette. Both healthy and anorexic women estimated their body shape differently than outsiders: healthy subjects rated themselves as thinner than the control subjects. Anorexic women on the other hand perceived themselves to be fatter than the control subjects did.
Brain areas for body perception examined with MRI
In MRI scanners, the researchers then recorded the brain activity of the 25 participants while they observed photos of bodies. Above all, they analysed the activity in the “fusiform body area” (FBA) and the “extrastriate body area” (EBA), because previous studies showed that these brain regions are critical for the perception of bodies. To this end, the neuroscientists from Bochum calculated the so-called effective connectivity between the FBA and EBA in both hemispheres. This is a measure of how much the activity in several brain areas is temporally correlated. A high degree of correlation is indicative of a strong connection.
Brains of anorexics structurally and functionally altered
The connection between the FBA and EBA was weaker in women with anorexia nervosa than in healthy women. In addition, the researchers found a negative correlation between the EBA-FBA connection in the left hemisphere and the misjudgement of body weight: the weaker the effective connectivity between the EBA and FBA was, the fatter the subjects with anorexia falsely estimated themselves to be. “In a previous study we found that there are structural changes in the brains of patients with anorexia”, says Boris Suchan. They have a lower density of nerve cells in the EBA. “The new data shows that the network for body processing is also functionally altered.” The EBA, which has a lower cell density in anorexics, is also the area that stood out in the connection analysis: it receives reduced input from the FBA. “These changes could provide a mechanism for the development of anorexia”, says Suchan.