Word: cortexes
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...first discoveries of neuroplasticity came from studies of how changes in the messages the brain receives through the senses can alter its structure and function. When no transmissions arrive from the eyes in someone who has been blind from a young age, for instance, the visual cortex can learn to hear or feel or even support verbal memory. When signals from the skin or muscles bombard the motor cortex or the somatosensory cortex (which processes touch), the brain expands the area that is wired to move, say, the fingers. In this sense, the very structure of our brain--the relative...
...overthrown the dogma. In its place has come the realization that the adult brain retains impressive powers of "neuroplasticity"--the ability to change its structure and function in response to experience. These aren't minor tweaks either. Something as basic as the function of the visual or auditory cortex can change as a result of a person's experience of becoming deaf or blind at a young age. Even when the brain suffers a trauma late in life, it can rezone itself like a city in a frenzy of urban renewal. If a stroke knocks out, say, the neighborhood...
...EXTREME EXAMPLE OF HOW CHANGES IN the input reaching the brain can alter its structure is the silence that falls over the somatosensory cortex after its owner has lost a limb. Soon after a car crash took Victor Quintero's left arm from just above the elbow, he told neuroscientist V.S. Ramachandran of the University of California at San Diego that he could still feel the missing arm. Ramachandran decided to investigate. He had Victor sit still with his eyes closed and lightly brushed the teenager's left cheek with a cotton swab...
...just below Victor's left nostril caused the boy to feel a tingling on his left pinkie. And when Victor felt an itch in his phantom hand, scratching his lower face relieved the itch. In people who have lost a limb, Ramachandran concluded, the brain reorganizes: the strip of cortex that processes input from the face takes over the area that originally received input from a now missing hand. That's why touching Victor's face caused brain to "feel" his missing hand...
Similarly, because the regions of cortex that handle sensations from the feet abut those that process sensations from the surface of the genitals, some people who have lost a leg report feeling phantom sensations during sex. Ramachandran's was the first report of a living being knowingly experiencing the results of his brain rewiring...