MONDAY, Dec. 27 (HealthDay News) -- The size of your amygdala, an almond-shaped portion of the brain involved in emotions, may be as strong a marker for having rich and varied social relationships as how many "friends" you have on Facebook, researchers say.
Scientists report in the Dec. 26 online edition of Nature Neuroscience that people with larger and more complex social networks also have larger amygdalas.
The findings correspond to previous research that found that primates also have a larger amygdala, relative to the overall size of their brain and body. Like humans, primates live in fairly complex social groups, suggesting that a larger amygdala has evolved to help navigate these landscapes.
The amygdala has also been shown to be involved with fear, emotion and even seizures, said Paul Sanberg, director of the University of South Florida Center of Excellence for Aging and Brain Repair in Tampa. Sanberg was not involved with the new study.
"It's part of the 'old' section of the brain," he explained, meaning the amygdala is common to many different species.
Earlier this month, researchers studying a woman without an amygdala found she did not fear a wide range of typically frightening stimuli such as snakes, spiders, horror films and a haunted house. Nor did she respond negatively when asked about traumatic experiences in her past.
That study was perhaps the first human study confirming that the brain structure is crucial for triggering fear, said the researchers, from the University of Iowa, who published their report in the Dec. 16 edition of Current Biology.
For this latest study, scientists at Harvard Medical School and Massachusetts General Hospital had 58 healthy adults aged 19 to 83 years answer questions about the number of people they maintained regular contact with and about the number of social groups they belonged to -
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