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A brief historical note
Q: How does the brain work?
Standard neuropsychological practice often involves comparing atypical to typical brain function in order to gain insight into how parts of the brain normally work. That is, scientists study atypical functioning not simply for its own sake, but also for what it can reveal about the ways in which all people learn and develop. The basic logic, simplified, runs like this: A person can do some task, such as make good decisions. The person sustains damage to a specific region in the brain, perhaps a part of the prefrontal cortex, and now has a deficit in ability to do the task—he or she can no longer make good decisions. Scientists then draw inferences about the role of the damaged area of the brain in typical ("normal") brains, based on analyses of the deficits in the patient.
One of the earliest and best-known studies has been the subject of speculation and debate since September 1848, when Phineas Gage, the 25-year-old foreman of a crew of railroad workers in Vermont, accidentally sparked an explosion that drove a tamping iron up through his left cheek bone and out the top of his skull. The tamping iron was over three feet long and passed through his skull with such force and speed that it landed one hundred yards behind him. Shortly after the accident, Gage was conscious and able to walk, and was driven by cart to Dr. John Harlow.
Gage survived, and Harlow wrote an account of the case which was met with great disbelief, as no one could believe that Gage could survive such an accident. Two years later, a second report was published by Henry J. Bigelow, professor of surgery at Harvard, who wrote that Gage was "quite recovered in faculties of body and mind."
Although his ability to reason seemed intact, his wife and friends noticed significant changes in his personality. The likable, capable, and proper young man became angry, rude, and irrational, shouting obscenities at anyone who seemed to stand in the way of his desires. In 1868, Harlow published his second account of the case, detailing all the symptoms and concluding that Gage's "mind was radically changed, so decidedly that his friends and acquaintances said he was 'no longer Gage.' "
The damage to his frontal cortex seemed to have erased many social inhibitions, and the case has provided rich fodder for over (top)
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150 years of speculation and debate about the specific disruptions to Gage's neural pathways. In 1994, Hannah Damasio and her colleagues at the University of Iowa used neuroimaging techniques to reconstruct Gage's skull in order to shed new light on the mystery. More recently, the research on the role of emotion in learning is informed by this case. Trauma to the prefrontal cortex, an area central to the integration of emotion and cognition, can impair the abilities to think logically, plan, and make good judgments. This discovery provided a basis for understanding that emotion and thinking are fully intertwined—an understanding with considerable implications for education. Emotion makes a fundamental contribution to thinking logically.
Although the case of Phineas Gage is extraordinary, it is not unique: Accidents and strokes have provided neuroscientists with patients suffering from all sorts of damage to different parts of the brain. Progress in understanding brain function would be less insightful and much slower without such patients. But studying atypical brain function may also result in some misunderstandings and myths about the brain. It is not difficult to imagine that associating loss of specific abilities with damage to particular parts of the brain might produce a theory of the brain as an organ composed of modules—the brain as a super-LEGO® structure—each brick responsible for a separate brain function. Jane can't speak, and she had a left-hemisphere stroke; therefore, the left hemisphere is responsible for speech; it's the speech module. In reality, brain function is the result of activity in networks that connect many regions—webs of electrical connections—not the result of isolated modules for speech or vision or some other specific activity.