They weren’t looking for the next “American Idol,” but scientists at the University of California recorded volunteers belting out “My Girl” by the Temptations, and then had them listen to their own voice without the accompanying music.
The researchers wanted to determine which parts of the brain are actually responsible for the uncomfortable feeling of embarrassment.
Then, to get an even better idea of the brain areas involved, the scientists recruited volunteers with neurodegenerative disease. When comparing the two groups, researchers were able to determine that embarrassment is rooted in the pregenual anterior cingulate cortex — a small bit of tissue in the right hemisphere of the front part of the brain.
The degree of the participants’ embarrassment depended on how well this region was functioning.
“In healthy people, watching themselves sing elicits a considerable embarrassment reaction,” said Dr. Virginia Sturm, a postdoctoral fellow at UC-San Francisco. Their blood pressure rises, their heart rate increases, and their breathing changes, she explained. People who had neurological damage in the medial frontal cortex, however, reacted more indifferently.
“This brain region predicted the behavior,” said Sturm. “The smaller the region, the less embarrassed the people were.”
Knowing that people with certain neurodegenerative diseases lose their ability to be embarrassed and also knowing which part of the brain governs that emotion may help with an earlier diagnosis of the disease.
Neurologists have long documented that people with frontotemporal dementia act in ways that would embarrass healthy people. This is caused by a progressive degeneration of the temporal and frontal lobes of the brain, which play a major role in decision-making and expression of emotion and language, including complex emotions like embarrassment.
As these parts of the brain weaken, people may behave oddly and lose their ability to interact with others. Growing evidence from research at UCSF and other medical centers has linked the loss of particular brain structures and neuronal networks to specific behavioral changes.
In the karaoke study, the researchers asked 79 people — most with neurodegenerative diseases — to sing the song as their vital signs were measured and cameras recorded their expressions.
The participants’ singing was played back to the singers at normal speed without the accompanying music. Then Sturm and her team assessed the volunteers’ embarrassment based on facial expressions and physiological markers, such as sweating and heart rate.
All of the participants had MRIs as well, which produced very accurate maps of their brains. The researchers used these maps to measure the volumes of the different regions of the brain and analyzed whether the sizes of those regions could predict embarrassment.
They found that those with significant neurodegeneration in the pregenual anterior cingulate cortex were less likely to get embarrassed. In fact, the more deterioration they had in this part of the brain, the less embarrassed they became. The volunteers were also given a “startle” test of in which they sat quietly in a room until startled by the sound of a loud gunshot.
“They do jump, and they are afraid,” said Sturm, “so it’s not like they don’t have any emotional reactions at all. But patients with loss in this brain region seem to lose these more complicated social emotions. Emotions like embarrassment are particularly vulnerable in neurodegenerative diseases that target the frontal lobes.”
Source: University of California