From political views to personal style, each of us has a set of preferences and beliefs that make up our sense of self. The biology underlying this self-image has proven difficult to figure out, but the results of a new study offer some insight. According to findings presented yesterday at the American Academy of Neurology's annual meeting in Philadelphia, researchers may have identified the part of the brain that controls our sense of self.
To explore the anatomy of self-image, neurologist Bruce L. Miller of the University of California at San Francisco and his colleagues studied people diagnosed with a rare disorder known as frontotemporal dementia. These individuals sometimes suffer from dramatic shifts in their sense of self. Indeed, several such cases among Miller's own patients prompted him to investigate this phenomenon. "One woman was a charming, dynamic real estate agent who went from wearing expensive designer apparel to choosing cheap clothing and gaudy beads and asking strangers the cost of their clothing," Miller recounts. "Her preference for fine dining in French restaurants turned into a love of fast food."
Of the 72 patients in the study, seven were identified as having had a dramatic change in their self. In six of these patients, medical imaging revealed that the area of the brain with the most severe degeneration from the disease was the right frontal lobe. (The seventh had the worst damage in the brain's right temporal lobe.) In contrast, of the 65 participants who did not experience a dramatic change in self-image, only one exhibited the most severe abnormalities in the right frontal lobe.
"This suggests that normal functioning of the right frontal lobe is necessary for people to maintain their sense of self," Miller concludes. "It shows that a biological disorder can not only have profound effects on behavior, but it can even break down well-established patterns of awareness and self-reflection."