One Brain...or Two? Show HandednessExactly why people are right-handed or left-handed is somewhat of a mystery. Dr. William Calvin has developed a fascinating theory about the origin of handedness and has written an essay called The Throwing Madonna to explain it. Right Side - Left SideIn 95% of right-handers, the left side of the brain is dominant for language. Even in 60-70% of left-handers, the left side of brain is used for language. Back in the 1860s and 1870s, two neurologists (Paul Broca and Karl Wernicke) observed that people who had damage to a particular area on the left side of the brain had speech and language problems. People with damage to these areas on the right side usually did not have any language problems. The two language areas of the brain that are important for language now bear their names: Broca's area and Wernicke's area. Images courtesy of Slice of Life. Cerebral DominanceEach hemisphere of the brain is dominant for other behaviors. For example, it appears that the right brain is dominant for spatial abilities, face recognition, visual imagery and music. The left brain may be more dominant for calculations, math and logical abilities. Of course, these are generalizations and in normal people, the two hemispheres work together, are connected, and share information through the corpus callosum. Much of what we know about the right and left hemispheres comes from studies in people who have had the corpus callosum split - this surgical operation isolates most of the right hemisphere from the left hemisphere. This type of surgery is performed in patients suffering from epilepsy. The corpus callosum is cut to prevent the spread of the "epileptic seizure" from one hemisphere to the other. Dominant FunctionsLeft Hemisphere
Right Hemisphere
Split-Brain ExperimentsDr. Sperry used a tachistoscope to present visual information to one hemisphere or the other. The tachistoscope requires people to focus on a point in the center of their visual field. Because each half of the visual field projects to the opposite site of the brain (crossing in the optic chiasm), it is possible to project a picture to either the right hemisphere OR the left hemisphere. More information:
Copyright © 1996-2021, Eric H. Chudler All Rights Reserved. Does the left cerebral hemisphere control the right side of the body?The left cerebral hemisphere controls movement of the right side of the body. Depending on the severity, a stroke affecting the left cerebral hemisphere may result in functional loss or motor skill impairment of the right side of the body, and may also cause loss of speech.
What is the right cerebral hemisphere responsible for?The right cerebral hemisphere controls movement of the left side of the body. Depending on the severity, a stroke affecting the right cerebral hemisphere may result in functional loss or motor skill impairment of the left side of the body.
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