The Biological Domai

Brain imaging techniques have enabled researchers to learn more about the brain's role in behavior and personality than previously thought possible.

lliot was a successful businessman, a proud father , and a good husband. At his firm, he was a role model for his younger colleagues. Personall , he was charming and pleasant. His social skills were such that he often was called on to settle disputes at work. Elliot was respected by others. His position in the community, his satisfying personal life, and his prosperity and professional status were all enviable.

One day Elliot began to have severe headaches. After a few days, he went to his doctor, who suspected a brain tumor. This suspicion was confirmed when a smal tumor was found growing, not on his brain, but on the lining of tissue that covers the brain. The location was just above his eyes, behind his forehead. The tumor was, however, pushing against his brain and had damaged a small portion of the front of his brain, part of the prefrontal cortex, which had to be removed with the tumor .

The operation went smoothly and Elliot recovered quickly , with no apparent lasting damage, at least none that could be found with ordinary tests. Elliot' s IQ was tested after the operation and was found to be superior , as it was before his operation. His memory was tested and was found to be excellent. His ability to use and understand language was also unaf fected by the operation. His ability to do arithmetic, to memorize lists of words, to visualize objects, to make judgments, and to read a map all remained unaf fected by the operation. All his cognitive functions remained normal or above normal, completely unaf fected by the removal of a small portion of his prefrontal cortex.

Brain imaging techniques have enabled researchers to learn more about the brain's role in behavior and personality than previously thought possible.

Elliot's family, however, reported that his personality had changed. He began to behave differently at work as well. He could not seem to manage his time properly . He needed lots of prompting from his wife to get going in the morning. Once at work, he had problems finishing tasks. If he was interrupted in a task, he had di ficulty startin back up where he had left of f. Often he would get captivated by one part of a task and get side-tracked for hours. For example, in refiling some books, which should have take 15 minutes, he stopped to read one of the books and returned to his desk hours later . He knew his job but just had trouble putting all the actions together in the right order .

Soon Elliot lost his job. He tried various business schemes on his own and finall took his life savings and started an investment management business. He teamed up with a disreputable character , against the advice of many of his friends and family members. This business went bankrupt, and he lost all his savings. To his wife and children Elliot appeared to be behaving impulsively , and they had trouble coping with the difficulties he was getting into. A divorce followed. Elliot quickly remarried, but to a woman whom none of his friends or family approved of. This marriage ended quickly in another divorce. Without a source of income, and without a family to support him, Elliot became a drifter .

Elliot came to the attention of Dr . Antonio Damasio, a neurologist at the University of Iowa, who later wrote a book about Elliot' s condition (Damasio, 1994). It seems that the small bit of brain matter destroyed by Elliot' s tumor was essential in transmitting emotional information to the higher reasoning centers of the brain. Elliot reported that the only change in himself that he noticed was that, after his operation, he did not feel any strong emotion, or much of any emotion for that matter .

The case of Elliot shows us that the body and the mind are intimately connected. Indeed, after Elliot' s operation, the biggest change in him was in his personality , not in his memory, his reasoning, or his knowledge.

Studies have shown that traumatic brain injury can lead to lar ge changes in personality (Tate, 2003). One of the most common changes in personality following brain injury is a diminished ability to inhibit or control one's impulses. This has been found in children who experienced brain trauma during birth (Christ, White, Brunstrom, & Abrams, 2003), in adults with traumatic brain injuries (Kim, 2002), and in elderly persons whose brains have been injured by stroke (Freshwater & Golden, 2002). This increased impulsivity and lack of self-control is most likely due to disruptions between the frontal lobes, which serve as the executive control center of the brain, and other parts of the brain. As a result, persons with extensive brain injury can retain most of their cognitive abilities, yet lose some degree of self-control (Lowenstein, 2002). Persons with personality changes following traumatic brain injuries often have spontaneous outbursts, sudden changes in mood, and episodes of aggression and can become quite disruptive to their families. Indeed, this is the personality profile of one of th most famous brain injury patients, Phineas Gage, who was injured by an iron rod that was blasted through his brain while he was working as a railway builder in the early 1900s (see A Closer Look).

The idea that elements of personality are the products of biological processes is an old one. In a.d. 170 ancient Roman physician Galen, building on even earlier work by Greek physician Hippocrates, wrote that personality or character was influence by biology. Galen taught that the amounts of four fluids present in the body deter mined personality: an abundance of phlegm made a person passive, calm, and thoughtful (phlegmatic); an abundance of blood made a person happy , outgoing, and lively (sanguine); too much yellow bile made a person unstable, aggressive, and excitable

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