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updated 4/15/2011 10:18:37 AM ET 2011-04-15T14:18:37

Flushed, red-hot cheeks. Sweating palms. Hearing your rendition of "My Girl" — but you aren't at karaoke. You are in the lab of Virginia Sturm at the University of California, San Francisco, and she's making you watch your own off-key rendition of The Temptations’ 1964 hit. 

Sturm's team is working to isolate the part of the brain in control of embarrassment. They've found that the feeling of embarrassment that comes with experiences such as hearing your own singing is isolated to a thumb-sized bit of tissue deep within your brain.

In people who show low levels of embarrassment — including those with dementia — this brain region is smaller than normal. "This region is actually essential for this reaction. When you lose this region, you lose this embarrassment response," Sturm told LiveScience. (Most of Sturm's study participants are actually patients with dementia, including disorders such as Alzheimer's disease.)

Personality centers

The embarrassment center is focused in an area called the pregenual anterior cingulate cortex; this tissue resides deep inside your brain, to the front and the right. This region is integral in regulating many automatic bodily functions, such as sweating, heartbeat and breathing, but also participates in many thinking-related functions, including emotions, reward-searching behaviors (like those implicated in addiction ) and decision-making.

"It has projections to higher centers and also has projections down to lower centers," Sturm said. "It has a dual role in both visceral and also motor reactions."

Size and shape of brain regions near this one have been associated with differences in personality. Scientists believe that the bigger a particular brain region, the more powerful the functions associated with it would be. For instance, extroverts have larger reward-processing centers, while anxious and self-conscious people have larger error-detection centers. Very giving people have larger areas associated with understanding other's beliefs, studies have shown.

Degeneration of embarrassment

Those with dementia tend to have lowered levels of embarrassment, even when watching themselves sing along to cheesy Motown hits.

Many things that those with dementia do, such as giving strangers massages or eating off of others' plates, don’t seem to embarrass them. When Sturm scanned their brains, she noticed that the less self-conscious and embarrassed the participants were, the smaller this embarrassment region in their cingulate cortex was.

Scanning this region of the brain could help diagnose these conditions earlier, since behavioral and social changes tend to happen before other symptoms that manifest themselves more obviously. "A better understanding of the emotional changes that occurring in these diseases could be helpful early in the course of disease when the diagnosis might not be so obvious," Sturm said. "There could be a host of emotional or social changes that go along with the diseases."

The work was presented in a talk by Sturm Thursday (April 14) at the 64th annual American Academy of Neurology meeting in Hawaii.  

You can follow LiveScience staff writer Jennifer Welsh on Twitter @microbelover.

© 2012 LiveScience.com. All rights reserved.

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