A Science Odyssey Probe The Brain

Mapping the Motor Cortex: a History

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What would you do if you were a doctor and had patients who were missing pieces of their skulls? If you were Eduard Hitzig, a German doctor working at a military hospital in the 1860s, you'd conduct some experiments. Hitzig, working on patients who had pieces of their skulls blown away in battle, stimulated exposed brains with wires connected to a battery. By doing so, he discovered that weak electric shocks, when applied to areas at the back of the brain, caused the patients' eyes to move.

Later, around 1870, Hitzig teamed up with another doctor, Gustav Fritsch. Setting up a makeshift lab in Fritsch's house, the two stimulated the brains of live dogs. They found that not only could they cause crude movements of the dogs' bodies, but that specific areas of the brain controlled specific movements.

Soon after, John Hughlings Jackson, an English scientist, took the work of Fritsch and Hitzig further. Based on his observations of his wife's epilectic seizures, Jackson came up with a more-detailed theory of how the brain controls muscles. He knew that every one of her seizures followed the same pattern: It would start at one of her hands, move to her wrist, then her shoulder, then her face. It would finally affect the leg on the same side of her body, then stop.

Jackson believed that the seizures were electrical discharges within the brain. The discharges started at one point and radiated out from that point. This suggested that the brain was divided into different sections, and that each section controlled the motor function (or movement) of a different part of the body. And since the pattern never varied, the way the brain is organized must also be set.

Part II: Wilder Penfield maps the brain.

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