Christine Kenneally on scientists' discovery of the part of the brain that controls much of our personality
YOU MAY NOT BE who you think you are. Your distaste for Lycra, your fondness for eighties music, the furtive pleasure you take in a corn dog -- all the habits and preferences that make you you -- may be no more fixed than the dial on a radio. According to neurologist Bruce L. Miller at the University of California, a large component of personality is controlled by a single area of the brain. If this area is damaged, it can change who you are.
Miller presented his findings Tuesday at the American Academy of Neurology's Fifty-Third Annual Meeting in Philadelphia. He investigated the anatomy of self by examining seventy-two people with frontotemporal dementia, a degenerative brain disease. Of these seventy-two, seven had undergone dramatic changes in personality. Even though their memory and language skills remained intact, the patients did 180-degree turns on the type of clothes they wore, the food they ate, and their political and religious beliefs.
Using magnetic resonance and single photon emission computerized tomography images, Miller and colleagues determined that the seven patients with dramatic changes in self had sustained the most damage to their brain's right frontal lobe (if you place the tip of your finger above your right eye, you'll be pointing at your right frontal lobe) and it is here, according to Miller, that the architecture of self-maintenance lies.
In one case, a religious woman who had been happily married for about forty years abruptly decided that she didn't like her husband anymore. He became very ill, but instead of being sympathetic, she decided that he was a terrible husband. He died soon after, and even then, the woman showed no remorse or feeling about him. After her husband's death, the woman met a Catholic priest whom she described as very handsome, and based on the priest's looks, she abandoned her lifelong Protestantism, and converted to Catholicism. Soon after conversion, she came into Miller's clinic with "a very florid frontal lobe dementia."
"Of course, it can be normal to change your philosophy," says Miller, "but to do it with little provocation or such flimsy reasons suggests some fragility in the sense of self." This fragility, according to Miller, is attributable to right frontal lobe damage. Another patient in the study, whom Miller described as "a charming dynamic real estate agent," went from wearing expensive clothes and eating in expensive restaurants to being "rude and disinhibited, gaudy in dress, and loving Taco Bell." In another case, a forty-year-old man with FTD who had always been "a critical, self-reliant person who recognized his own mistakes" became someone who was often "fired for irresponsible behavior." On the bright side, the same patient "went from being tight-fisted and short-tempered to relaxed and easy going at home," said Miller. "His views about sex, which had been puritanical, were now tolerant and even experimental -- he even urged his children to share his new uninhibited philosophy."
Although the original personality may have some influence on the new self -- perhaps some unexpressed tendencies are finally coming out -- Miller believes it is primarily the changes in anatomy that structure the new personality. "As damage to the left hemisphere interrupts language, so injuries to the right hemisphere will disrupt personality and social behavior."
Until recent advances in imaging techniques, the brain areas involved in maintaining a person's sense of self were unknown. Indeed, the question of how much of our brain function is localized in specific areas of the brain has been debated for hundreds of years. There are no simple answers. Dr. David Knopman, a neurologist at the Mayo Clinic in Rochester, Minnesota, cautions that it's important to not overinterpret such dramatic results, believing that "cognition and higher mental functions are more diffusely represented in the cerebral hemispheres than studies of brain injury would imply." Nevertheless, what is new about this research, he says, is that "this is one of the first studies that considered the topic of 'self' as something to be specifically studied."
All the FTD patients were aware that they had dramatically changed as a result of the disease, but their reactions to their transformation were emotionally shallow. "They could describe it," said Miller, "but instead of talking about it as a major life change, it was like they were having a cup of coffee in the morning." Family and friends of the seven patients, however, were affected by the changes and felt that the patients had become very different people. They could discern no essential self remaining.
Many will not be surprised to learn that voting Republican or eating Taco Bell may be a symptom of dementia. But what about the belief that we are more than a collection of habits and preferences, that there is something unique and indefinable about every special one of us? "The self is anatomy and biology and it develops through experiences," says Miller, who admits the findings have forced him to reflect upon this issue. "It is the coding of these experiences into our brain that is the key to maintenance of self. When we lose that coding, the self becomes fragile," he said matter-of-factly, "and it is easily tilted over."
Christine Kenneally is
an Australian writer who lives in New York.