My Stroke of Insight: A Brain Scientist's Personal Journey (5 page)

Under the conditions of commissurotomy where background factors are equalized and where close left-right comparisons become possible within the same subject working the same problem, even slight lateral differences become significant. The same individual can be observed to employ consistently one or the other of two distinct forms of mental approach and strategy, much like two different people, depending on whether the left or right hemisphere is in use.
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Since those early studies of split-brain patients, neuroscientists have learned that the two hemispheres perform differently when they are connected to one another than when they are surgically separated.
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When normally connected, the two hemispheres complement and enhance one another's abilities. When surgically separated, the two hemispheres function as two independent brains with unique personalities, often described as the Dr. Jekyll and Mr. Hyde phenomenon.

Using noninvasive modern techniques including functional imaging (fMRI), scientists are now capable of visualizing which specific neurons are engaged in performing a designated function in real time. Because our two hemispheres are so neuronally integrated via the corpus callosum, virtually every cognitive behavior we exhibit involves activity in both hemispheres - they simply do it differently. As a result, the world of science supports the idea that the relationship between the two cerebral hemispheres is more appropriately viewed as two complementary halves of a whole rather than as two individual entities or identities.

It makes sense that having two cerebral hemispheres that process information in uniquely different ways would increase our brain's capacity to experience the world around us and increase our chances of survival as a species. Because our two hemispheres are so adept at weaving together a single seamless perception of the world, it is virtually impossible for us to consciously distinguish between what is going on in our left hemisphere versus our right hemisphere.

To begin, it is important to understand that hemispheric dominance is not to be confused with hand dominance. Dominance in the brain is determined by which hemisphere houses the ability to create and understand verbal language. Although the statistics vary depending upon whom you ask, virtually everyone who is right handed (over 85% of the U.S. population) is left hemisphere dominant. At the same time, over 60% of left handed people are also classified as left hemisphere dominant. Let's take a closer look at the asymmetries of the two hemispheres.

Our right hemisphere (which controls the left half of our body) functions like a parallel processor. Independent streams of information simultaneously burst into our brain via each of our sensory systems. Moment by moment, our right mind creates a master collage of what this moment in time looks like, sounds like, tastes like, smells like, and feels like. Moments don't come and go in a rush, but rather are rich with sensations, thoughts, emotions, and often, physiological responses. Information processed in this way allows us to take an immediate inventory about the space around us and our relationship to that space.

Thanks to the skills of our right mind, we are capable of remembering isolated moments with uncanny clarity and accuracy. Most of us can remember where we were and how we felt when we first heard about the assassination of President Kennedy or saw the collapse of the World Trade Center. Do you remember the moment you spoke the words "I do," or first saw your newborn smile? Our right hemisphere is designed to remember things as they relate to one another. Borders between specific entities are softened, and complex mental collages can be recalled in their entirety as combinations of images, kinesthetics, and physiology.

To the right mind, no time exists other than the present moment, and each moment is vibrant with sensation. Life or death occurs in the present moment. The experience of joy happens in the present moment. Our perception and experience of connection with something that is greater than ourselves occurs in the present moment. To our right mind, the moment of
now
is timeless and abundant.

In the absence of all the rules and regulations that have already been defined as the correct way of doing something, our right mind is free to think intuitively outside the box, and it creatively explores the possibilities that each new moment brings. By its design, our right mind is spontaneous, carefree, and imaginative. It allows our artistic juices to flow free without inhibition or judgment.

The present moment is a time when everything and everyone are connected together as
one
. As a result, our right mind perceives each of us as equal members of the human family. It identifies our similarities and recognizes our relationship with this marvelous planet, which sustains our life. It perceives the big picture, how everything is related, and how we all join together to make up the whole. Our ability to be empathic, to walk in the shoes of another and feel their feelings, is a product of our right frontal cortex.

In contrast, our left hemisphere is completely different in the way it processes information. It takes each of those rich and complex moments created by the right hemisphere and strings them together in timely succession. It then sequentially compares the details making up this moment with the details making up the last moment. By organizing details in a linear and methodical configuration, our left brain manifests the concept of time whereby our moments are divided into the past, present, and future. Within the structure of this predictable temporal cadence, we can appreciate that this must occur before that can happen. I look at my shoes and socks and it is my left hemisphere that comprehends that I must put my socks on before my shoes. It can look at all the details of a puzzle and use the clues of color, shape, and size to recognize patterns for arrangement. It builds an understanding of everything using deductive reasoning such that if A is greater than B, and B is greater than C, then A must be greater than C.

Just opposite to how our right hemisphere thinks in pictures and perceives the big picture of the present moment, our left mind thrives on details, details, and more details about those details. Our left hemisphere language centers use words to describe, define, categorize, and communicate about everything. They break the big picture perception of the present moment into manageable and comparable bits of data that they can talk about. Our left hemisphere looks at a flower and names the different parts making up the whole -the petal, stem, stamen, and pollen. It dissects the image of a rainbow into the language of red, orange, yellow, green, blue, indigo, and violet. It describes our body as arms, legs, a torso, and every anatomical, physiological, and biochemical detail one can imagine. It thrives on weaving facts and details into a story. It excels in academics, and by doing so, it

manifests a sense of authority over the details it masters.

Via our left hemisphere language centers, our mind speaks to us constantly, a phenomenon I refer to as "brain chatter." It is that voice reminding you to pick up bananas on your way home and that calculating intelligence that knows when you have to do your laundry. There is vast individual variation in the speed at which our minds function. For some, our dialogue of brain chatter runs so fast that we can barely keep up with what we are thinking. Others of us think in language so slowly that it takes a long time for us to comprehend. Still others of us have a problem retaining our focus and concentration long enough to act on our thoughts. These variations in normal processing stem back to our brain cells and how each brain is intrinsically wired.

One of the jobs of our left hemisphere language centers is to define our
self
by saying "I am." Through the use of brain chatter, your brain repeats over and over again the details of your life so you can remember them. It is the home of your ego center, which provides you with an internal awareness of what your name is, what your credentials are, and where you live. Without these cells performing their job, you would forget who you are and lose track of your life and your identity.

Along with thinking in language, our left hemisphere thinks in patterned responses to incoming stimulation. It establishes neurological circuits that run relatively automatically to sensory information. These circuits allow us to process large volumes of information without having to spend much time focusing on the individual bits of data. From a neurological standpoint, every time a circuit of neurons is stimulated, it takes less external stimulation for that particular circuit to run. As a result of this type of reverberating circuitry, our left hemisphere creates what I call "loops of thought patterns" that it uses to rapidly interpret large volumes of incoming stimulation with minimal attention and calculation.

Because our left brain is filled with these ingrained programs of pattern recognition, it is superb at predicting what we will think, how we will act, or what we will feel in the future - based upon our past experience. I, personally, love the color red and am inclined to collect a bunch of red things - I drive a red car and wear red clothes. I like red because there's a circuit in my brain that gets very excited and runs relatively automatically when anything red comes my way. From a purely neurological perspective, I like red because the cells in my left brain tell me I like red.

Among other things, our left hemisphere categorizes information into hierarchies including things that attract us (our likes) or repel us (our dislikes). It places the judgment of good on those things we like and bad on those things we dislike. Through the action of critical judgment and analysis, our left brain constantly compares us with everyone else. It keeps us abreast of where we stand on the financial scale, academic scale, honesty scale, generosity-of-spirit scale, and every other scale you can imagine. Our ego mind revels in our individuality, honors our uniqueness, and strives for independence.

Although each of our cerebral hemispheres process information in uniquely different ways, the two work intimately with one another when it comes to just about every action we undertake. With language, for example, our left hemisphere understands the details making up the structure and semantics of the sentence - and the meaning of the words. It is our left mind that understands what letters are and how they fit together to create a sound (word) that has a concept (meaning) attached to it. It then strings words together in a linear fashion to create sentences and paragraphs capable of conveying very complex messages.

Our right hemisphere complements the action of our left hemisphere language centers by interpreting non-verbal communication. Our right mind evaluates the more subtle cues of language including tone of voice, facial expression, and body language. Our right hemisphere looks at the big picture of communication and assesses the congruity of the overall expression. Any inconsistencies between how someone holds their body, versus their facial expression, versus their tone of voice, versus the message they are communicating, might indicate either a neurological abnormality in how someone expresses himself or it may prove to be a telltale sign that the person is not telling the truth.

People who have damage in their left hemisphere often cannot create or understand speech because the cells in their language centers have been injured. However, they are often genius at being able to determine if someone is telling the truth, thanks to the cells in their right hemisphere. On the other hand, if someone has damage to their right hemisphere, they may not appropriately assess the emotional content of a message. For example, if I am playing blackjack at a party and I say, "hit me!" a person with a damaged right hemisphere may think I am asking him to physically strike me rather than understand that I am simply asking for another card. Without the right hemisphere's ability to evaluate communication in the context of the bigger picture, the left hemisphere tends to interpret everything literally.

Music is another great example of how our two hemispheres complement one another in function. When we methodically and meticulously drill our scales over and over again, when we learn to read the language of staff notation, and when we memorize which fingering on an instrument will create which named note, we are tapping primarily into the skills of our left brain. Our right brain kicks into high gear when we are doing things in the present moment - like performing, improvising or playing by ear.

Did you ever stop to consider how it is that your brain knows how to define the dimensions of your body in space?

Amazingly, there are cells in our left hemisphere's orientation association area that define the boundaries of our body -where we begin and where we end relative to the space around us. At the same time, there are cells in our right hemisphere's orientation association area that orient our body in space. As a result, our left hemisphere teaches us where our body begins and ends, and our right hemisphere helps us place it where we want it to go.
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I enthusiastically encourage you to explore the myriad of current literature about teaching and the brain, learning and the brain, and the asymmetries of our two cortical hemispheres. I believe that the more we understand about how our hemispheres work together to create our perception of reality, then the more successful we will be in understanding the natural gifts of our own brains, as well as more effectively help people recover from neurological trauma.

The type of stroke I experienced was a severe hemorrhage in the left hemisphere of my brain due to an undiagnosed AVM. On the morning of the stroke, this massive hemorrhage rendered me so completely disabled that I describe myself as an infant in a woman's body. Two and a half weeks after the stroke, I underwent major surgery to remove a golf ball-sized blood clot that was obstructing my brain's ability to transmit information.