The amiable, soft-spoken Gage had become irritable, rude, irresponsible, and dishonest. For instance, consider the well-known case of Phineas Gage (Figure 4.12), a 25-year-old railroad worker who, as a result of an explosion, had an iron rod driven into his cheek and out through the top of his skull, causing major damage to his frontal lobe (Macmillan, 2000). Although, remarkably, Gage was able to return to work after the wounds healed, he no longer seemed to be the same person to those who knew him. It is now known that a good part of our moral reasoning abilities is located in the frontal lobe, and at least some of this understanding comes from lesion studies. Areas in the frontal lobe of Phineas Gage were damaged when a metal rod blasted through it. In fact, our earliest understanding of the specific areas involved in speech and language were gained by studying patients who had experienced strokes. For instance, if the stroke influences the occipital lobe, then vision may suffer, and if the stroke influences the areas associated with language or speech, these functions will suffer. In some cases, the result of the stroke is a specific lack of ability. For instance, when an individual suffers a stroke, a blood clot deprives part of the brain of oxygen, killing the neurons in the area and rendering that area unable to process information. Lesions allow the scientist to observe any loss of brain function that may occur. In so doing, they hope to be able to draw inferences about the likely functions of human brains from the effects of the lesions in animals. Psychologists also sometimes intentionally create lesions in animals to study the effects on their behaviour. In rare occasions, brain lesions may be created intentionally through surgery, such as that designed to remove brain tumours or (as in split-brain patients) reduce the effects of epilepsy. The brains of living human beings may be damaged - as a result of strokes, falls, automobile accidents, gunshots, or tumours, for instance. In other cases, however, we can study living brains. Lesions Provide a Picture of What Is MissingĪn advantage of the cadaver approach is that the brains can be fully studied, but an obvious disadvantage is that the brains are no longer active. Diamond admits a limitation in her study is that she had only one Einstein to compare with 11 ordinary men. Although she found that Einstein’s brain had relatively more glia in all the areas that she studied than did the control group, the difference was only statistically significant in one of the areas she tested. However, Diamond was able to find support for only part of her research hypothesis. To test this hypothesis, she compared the ratio of glia to neurons in Einstein’s brain with the ratio in the preserved brains of 11 other more “ordinary” men.
Diamond was interested in the role of glia, and she hypothesized that the ratio of glial cells to neurons was an important determinant of intelligence. Researcher Marian Diamond (1999) later analyzed a section of Einstein’s cortex to investigate its characteristics. When Albert Einstein died in 1955, his brain was removed and stored for later analysis. Perhaps the most immediate approach to visualizing and understanding the structure of the brain is to directly analyze the brains of human cadavers. Each of the different techniques has some advantages, and when we put them together, we begin to get a relatively good picture of how the brain functions and which brain structures control which activities. In this section we will consider the various techniques that psychologists use to learn about the brain. But there are a variety of empirical methods that allow scientists to look at brains in action, and the number of possibilities has increased dramatically in recent years with the introduction of new neuroimaging techniques. One problem in understanding the brain is that it is difficult to get a good picture of what is going on inside it. Compare and contrast the techniques that scientists use to view and understand brain structures and functions.
0 kommentar(er)
