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Techniques Used Today
Advanced techniques for studying the brain and the nervous system have added greatly to our understanding of the relationship between biology and behavior. Today there are five main approaches for studying the brain.
1. Electron microscopes are used to analyze brain and other nerve cells after the organisms have died. They can magnify nerve cells many thousands of times. Microscopic analysis has identified not only the physical structure of these cells, but their chemical makeup as well.
2. Injection of drugs into the brains of laboratory animals allows the study of behavior changes in the living organism. This is done by implanting tiny tubes in different areas of the brain and then applying very small amounts of drugs in various strengths directly to brain sites.
By using the brains of living animals, scientists can more precisely study the chemical and biological processes that are at work.
3. Lesioning of brain tissue is done in live animals by severing a nerve area or removing a section of brain, and then observing the performance of the animals. Karl Lashley was one of the pioneers in this technique. Removing different regions of rats' brains, he found, affected the rats' ability to remember their way around a maze. However, it was not the specific section that was cut out, but rather, the amount. Even with the removal of much brain tissue, the rats were still able to perform, although at a much simpler level. Memory storage thus appears to be widely distributed in the brain.
4. The brain, as the body's control center, functions electrically. As brain cells work, they give off tiny amounts of electrical energy. The general electrical activity of the brain can be measured by an electroenceph-alograph or EEG machine. Wires from the EEG machine are taped to several points on the head. Electrical energy from the brain activates a pen on moving graph paper. Certain brain cells release electrical energy in rhythms; these rhythms, or brain-wave patterns, are recorded on paper. As the brain performs different functions, from sleeping to intense thought, the patterns change. In effect, the brain is "writing" out its messages, leaving scientists to determine what type of mental activity is taking place.
Because every person has different brain-wave patterns, the expression "being on a different wave length" is not just a figure of speech. A young child has a wave pattern quite distinct from an older person, while identical twins have very similar EEGs. Yet, like fingerprints, the brain waves of no two persons are exactly the same. Unlike fingerprints, brain waves change constantly, reflecting the unique electrical activity taking place at a given moment. When the EEG is "flat"— when no activity is present in the brain—the brain is dead.
5. In the 1930s, Dr. Wilder Penfield of the Montreal Neurological Institute pioneered a promising new technique for treating patients who suffered from epileptic seizures—a technique that makes The Terminal Man look outdated 40 years later. He stimulated different parts of the brain with a mild electric current.
Although Penfield's purpose was to relieve the patient's disorder, in the process he learned how the brain functions in more precise ways than had ever been known before. Patients were fully conscious during treatment. (The brain, although it is largely made up of nerves, does not "feel" anything itself.) So they were able to report just exactly how they felt. "There's a tingling in my left thumb . . . now it's on the left side of my tongue . . . now my tongue is moving . . ." People "saw" scenes from their childhood that had been long forgotten. As a result of sessions like this, Penfield was able to "map" a large part of the brain. He also concluded that nothing the brain takes in is ever really lost.
Another result of this technique was the discovery of pleasure sites in the brain. James Olds taught rats to press a lever that delivered electrical stimulation to the pleasure sites in their own brains. So rewarding was the experience that some rats pressed the lever 7,000 times an hour, passing up food even though they were hungry.
Many believe experiments with animals are cruel and unnecessary. And some question the use of electrical stimulation to control human behavior. Recently, the medical profession has begun to set up guidelines to protect people from over-enthusiastic brain tinkerers. The question of animal experimentation is as yet unanswered. The ultimate issue is the use of power: who should have the power to push your button?
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