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Thursday, January 10, 2008

Later localizationists

Later localizationists
Studies performed in Europe by scientists such as John Hughlings Jackson caused the localizationist view to re-emerge as the primary view of behavior. Jackson studied patients with brain damage, particularly those with epilepsy. He discovered that the epileptic patients often made the same clonic and tonic movements of muscle during their seizures, leading Jackson to believe that they must be occurring in the same place every time. Jackson proposed a topographic map of the brain, which was critical to future understanding of the brain lobes.
Broca's area and Wernicke's area.In 1861, French neurologist Paul Broca came across a man who was able to understand language but unable to speak. The man could only produce the sound "tan". It was later discovered that the man had damage to an area of his left frontal lobe now known as Broca's area. Carl Wernicke, a German neurologist, found a similar patient, except that this patent could speak fluently but non-sensibly. The patient has been a victim of a stroke, and could not understand spoken or written language. This patient had a lesion in the area where the left parietal and temporal lobes meet, now known as Wernicke's area. These cases strongly supported the localizationists views, because a lesion caused a specific behavioral change in both of these patients.
In 1870, German physicians Eduard Hitzig and Gustav Fritsch published their findings about the behavior of animals. Hitzig and Fritsch ran an electrical current through the cerebral cortex of a dog, causing the dog to produce characteristic movements based on where the current was applied. Since different areas produced different movements, the physicians concluded that behavior was rooted at the cellular level. German neuroanatomist Korbinian Brodmann used tissue staining techniques developed by Franz Nissl to see the different types of cells in the brain. Though this study, Brodmann concluded in 1909 that the human brain consisted of fifty-two distinct areas, now named Brodmann areas. Many of Brodmann's distinctions were very accurate, such as differentiating Brodmann area 17 from Brodmann area 18.

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