It is certainly true that the brain is split anatomically and functionally into left and right halves. Anatomically, each side of the brain controls the nerves and muscles in the arm and leg on the opposite side of the body - i.e., the left side of your brain controls your right arm and leg, and vice versa. You might see this phenomenon demonstrated in your everyday observations if you happen to come across an individual who has had a stroke or a severe head injury. A person who has had an injury to the right side of the brain may have partial or even total loss of function to the left side of the body. Therefore, when we're talking about relatively simple motor and sensory functions such as moving and feeling, the left and right halves of the brain work in much the same way.

However, in recent times, neurologists and neuropsychologists have found that the left and right halves of the brain do not function in exactly the same way when it comes to more complicated issues. Perhaps the most profound differences between the hemispheres of the brain are seen with the location of language function. For the overwhelming majority of right handed people, the left side of the brain is responsible for language functions. How do we know this? Neurologists who deal with persons who have had a stroke in a specific area in the brain called the left temporal lobe see a typical scenario where language is impaired either focally or globally. In right handed persons, some type of language impairment is almost always evident.

The degree of language impairment is variable, depending how large the area of stroke is, and the exact location of the stroke. A small stroke will cause only minor problems such as word-finding difficulty, or, for example, a stutter. A large stroke, where the majority of the left temporal lobe is involved, can result in a total loss of language function. The person afflicted by a large stroke may not only be unable to speak or write, but may not even be able to understand spoken or written language. These people are lost in a world of pure sensation, without the language interpreter or mediator of reality. The few people who have recovered from such severe losses relate a chilling story of how frightening this experience is.

Given this level of specialization of the left brain, you might think that the right side of the brain would be similarly as specialized, but this is not quite the case. When someone has damage or a stroke to the right side of the brain, the behavioral consequences are not as clear cut.

The right brain functions appear to be more subtle, and often more elusive. Right brain damage may lead to a condition known as aprosodia, where the person's speech capabilities are still intact, but the rhythm is off; speech will seem robotic and unnatural. Relationships between three-dimensional objects is affected, and right brain impaired individuals have a tendency to get lost easily, because geography becomes very difficult to navigate.Where did the right brain equals creative and left brain equals analytical idea come from? It was in the 1970s when researchers and physicians began to actively study the separate funcitons of the left and right hemispheres. Much of the work came from studies of individuals who had the left and right sides disconnected as a treatment for epilepsy.

By using special types of glasses which enable medical researchers to present words and images to only one side of the brain at a time, it was discovered that these individuals with split brains would respond quite differently, depending on which side of their brains saw the word or image.

Essentially, the right side was able to respond emotionally to stimuli, such as a picture of a couple fighting, while the left side of the brain would have essentially no response. If the right side were presented with a sentence or a mathematical equation there would be no response, but the left side would be able to quickly and accurate interpret the meaning of the stimulus.

In the cultural environment of the seventies, this split between emotional and analytic thought was interpreted as "creative" vs. "non-creative". A boom in the book publishing industry took place with the release of numerous titles focusing on such topics as enhancing the right brain. People began to think of themselves "left brained" or "right brained" depending on whether they considered themselves the emotionally oriented type or the rational and rules-oriented type. Since in the public's mind many artists "march to the beat of a different drum" and do not follow the standard rules of behavior in society, the fundamental concept of human tendency to a right/left split seemed to make sense.

So, are you a left-brained or right-brained person? Well, the truthful answer is that this is a misleading question. In fact, you are both. Based on your heredity (genetics), your environment and your present state of health, you may be more or less analytic, more or less emotional, or more or less artistic. But above all, you are a whole person who uses both sides of the brain, taking advantage of the more than 100 billion connections between the two. If you are an artist, you translate your emotional experience into some sort of organized, planned expression of those emotions. If you are an accountant, you may find that certain numbers or patterns evoke an emotional response. However, no matter what your personal or professional inclinations, the plain fact is that both sides of your brain are constantly invoked as you go about daily life.

Therefore the next time you come across a book, a cassette tape, or a therapist who purports to have the key to unlocking the powers of your right brain, keep these things in mind. You've got to watch out in today's medical arena; some folks out there will try to sell you anything that they can get you to believe has a legitimate medical application, no matter how improbable. But you know better, because Your Health Matters.