ventromedial prefrontal cortex

the rear part of the prefrontal cortex, including the cortex on top of the orbits of both eyes and the inside part of the frontal lobes.

Children with autism have distinctive patterns of brain activity

December, 2010

An imaging study has found three different brain signatures discriminating children with autistic spectrum disorders, siblings of children with ASD, and other typically-developing children.

Last month I reported on a finding that toddlers with autism spectrum disorder showed a strong preference for looking at moving shapes rather than active people. This lower interest in people is supported by a new imaging study involving 62 children aged 4-17, of whom 25 were diagnosed with autistic spectrum disorder and 20 were siblings of children with ASD.

In the study, participants were shown point-light displays (videos created by placing lights on the major joints of a person and filming them moving in the dark). Those with ASD showed reduced activity in specific regions (right amygdala, ventromedial prefrontal cortex, right posterior superior temporal sulcus, left ventrolateral prefrontal cortex, and the fusiform gyri) when they were watching a point-light display of biological motion compared with a display of moving dots. These same regions have also been implicated in previous research with adults with ASD.

Moreover, the severity of social deficits correlated with degrees of activity in the right pSTS specifically. More surprisingly, other brain regions (left dorsolateral prefrontal cortex, right inferior temporal gyrus, and a different part of the fusiform gyri) showed reduced activity in both the siblings group and the ASD group compared to controls. The sibling group also showed signs of compensatory activity, with some regions (right posterior temporal sulcus and a different part of the ventromedial prefrontal cortex) working harder than normal.

The implications of this will be somewhat controversial, and more research will be needed to verify these findings.

Reference: 

[1987] Kaiser, M. D., Hudac C. M., Shultz S., Lee S. M., Cheung C., Berken A. M., et al.
(2010).  Neural signatures of autism.
Proceedings of the National Academy of Sciences.

Full text available at http://www.pnas.org/content/early/2010/11/05/1010412107.full.pdf+html

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Why older adults remember the good times better

March, 2010

An imaging study has found differences in brain activity that explain why older adults are better at remembering positive events.

An imaging study reveals why older adults are better at remembering positive events. The study, involving young adults (ages 19-31) and older adults (ages 61-80) being shown a series of photographs with positive and negative themes, found that while there was no difference in brain activity patterns between the age groups for the negative photos, there were age differences for the positive photos. In older adult brains, but not the younger, two emotion-processing regions (the ventromedial prefrontal cortex and the amygdala) strongly influenced the memory-encoding hippocampus.

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