BRAIN ANATOMY AND PERSONALITY

My father, Hal Taylor, was a preacher man. He was an ordained and practicing Episcopalian minister during my childhood, and when I was a teenager he became a therapist after receiving his Ph.D. in counseling psychology. Hal was fascinated with people of all walks of life and earned his living helping corporations and nonprofit organizations develop teambuilding skills for better board management and performance. He did this using personality profiles and temperament typing.

Hal was obsessed with helping people help themselves, be they presidents of organizations, the severely mentally ill, or those incarcerated in our jails. Hal had a heart of gold, and his single goal in life, in my opinion, was to help people better understand their strengths so they could live more fully. Temperament typing was a great tool for this. His primary tool was the Myers-Briggs Type Indicator, which was very popular back in the 1970s, ’80s, and ’90s and is still being used by over a million people a

year.

The first time Hal gave me the Myers-Briggs, I was 18 years old and starting college. Like many others I rebelled against the forced-choice nature of the exam because my answers were completely dependent on the circumstances in which I pictured myself. I originally tested as an INTJ— an Introverted, Intuitive, Thinking, and Judging personality. This profile, labeled by psychologist and temperament-typing expert David Keirsey as the Scientist, clearly depicted a character inside of me, but I was that character only part of the time. When hanging out with my friends, I was an ESFP Performer type—Extroverted, Sensing, Feeling, and Perceiving. So much so that I was voted class clown in high school.

The Myers-Briggs did not accommodate for different life scenarios, and because it pigeonholed me into a single character, I questioned the accuracy of the evaluation. This sparked in me a lifelong curiosity and drive to find a psychological typing system that was more anatomically accurate.

Following in my father’s footsteps, I became fascinated with psychology and the brain, as well as with the relationships between our mind, brain, body, and behavior. I loved anything that was human-based biology.

THE SPLIT-BRAIN EXPERIMENTS

To my good fortune, I was an undergraduate during the late ’70s, when the field of neuroscience went mainstream and the famous split-brain surgeries captivated the public’s attention. To say the least, I was riveted by the work of Dr. Roger Sperry, who surgically separated the two cerebral hemispheres of several of his epileptic patients.

When Dr. Sperry surgically cut the corpus callosum—the band of some 300 million axonal fibers connecting the two cerebral hemispheres—in a procedure called a commissurotomy, he was successful in preventing dangerous seizure activity in one hemisphere from spreading into the other. There was another benefit too: the psychological experiments that were performed on this patient population by Dr. Michael Gazzaniga bore great insights into how our two brain hemispheres function differently when they are separated.

As a budding neuroscientist, I was particularly fascinated by the Dr. Jekyll and Mr. Hyde stories from these experiments, which depicted the psychological and underlying anatomical abilities of the two cerebral hemispheres as dramatically different. It was clear that when the two hemispheres were separated, the split-brain patients behaved as though they were two unique characters that often acted in direct opposition to one another.

In some of these patients, the character “occupying” the right brain hemisphere would directly contradict the intention and behavior of the character “occupying” the left brain hemisphere. For instance, when one gentleman attempted to slap his wife with his left hand (right brain), he simultaneously protected her with his right hand (left brain). On another occasion this same fellow was clearly conflicted when he yanked his pants down with one hand while simultaneously redressing himself with the other.

A different patient, who happened to be a child, was completely verbal in both of his hemispheres. When asked about his life goals, his right-brain character reported that he wanted to grow up to be a race car driver, while his left-brain character was interested in becoming a draftsman. Still another commissurotomy patient reported that she went to battle with

herself every morning when choosing her clothing. She described her right and left hands as two repelling magnets, each of which had different styles in mind about what she should wear that day. The same thing happened when she was shopping for food at the grocery store, as her two hemispheric characters were interested in completely different cuisines. It took well over a year following her commissurotomy surgery before she was able to master a single intention and purposefully inhibit the internal battle going on between her two differently opinionated hemispheric characters.

As you hear these stories, it is important to note that the only anatomical difference between these commissurotomy patients and you and me is that our two cerebral hemispheres communicate with one another via the connections of our corpus callosum. Scientists understand that neuroanatomically the majority of these commissural fibers are inhibitory in nature and that they run from one set of cells in one hemisphere to the comparable set of cells in the opposite hemisphere. At any moment in time, both hemispheres have cells that are active, but opposing hemisphere cell groups dance between dominance and inhibition.

In this way, one hemisphere has the power to inhibit the function of the comparable cells in the opposite hemisphere, dominating the function of that particular group of cells. For example, when we are focused on the words and meaning of what someone is saying (left brain), we tend to not be so focused on the inflection of their voice or the emotional content (right brain) of what they are communicating. Vice versa—have you ever been so stunned that someone was yelling at you that you completely missed the point they were trying to make?

Back in the ’70s and ’80s, society went a bit overboard in its response to the split-brain studies, and all sorts of “right brain” and “left brain”–based community programs popped up. Many schools even got into the game and established curricula that would help stimulate one or both of the hemispheres. The stereotypes of left-brain and right-brain people entered the mainstream, with the left-brainers appearing to be more organized, punctual, and good with details while the right-brainers thrived in creativity, innovation, and athletics.

Unfortunately, in response to the left-brain/right-brain craze, the strategy that many parents took to help their children get ahead was to expose them to programming that fit their natural dominance. This makes sense, of

course, since they wanted their children to be rewarded for what they did well. But if their goal was to create more rounded, whole-brained children, a better plan might have been for them to encourage their kids to partake in activities at which they did not excel. For example, they could have encouraged the left brain–dominant science and math types to participate in outdoor events in which they could explore and collect data in the woods. And they could have enticed the athletic and artistic types to creatively design some really cool science-fair projects that would measure some type of performance.

Because parents did it the way they did, however, over the last 40 years we have skewed our abilities toward the two extremes. There have been some writings and teachings specifically designed to help develop our nondominant side, including the book Drawing on the Right Side of theBrain, which is a classic and still widely used today. Also, you don’t have to look far to recognize how marketers have mastered their advertising strategies to target our right- or left-brain preferences. Even our computer systems fit the bill: Apple products are viewed as right-brain creative, while anything Windows based screams left-brain analytical. Remember that Blackberry? It used to make my right brain moan.

HOW THE TWO HEMISPHERES FUNCTION

In addition to these pop-science efforts that have been designed to capitalize on the stereotypical differences between our two hemispheres, a tome of evidence-based science now offers us a pretty clear understanding of both the anatomical and functional differences between the two halves of our brain. For anyone interested in both the big picture and the details about what we have learned concerning these differences over the last half century, The Master and His Emissary, a book by the British psychiatrist Dr. Iain McGilchrist, is a fascinating and up-to-date read.

In addition, if you are interested in how a Harvard psychiatrist works with the left- and right-brain characters in an attempt to help his patients heal issues related to mental illness, the book Of Two Minds by Dr. Fredric Schiffer is a real eye-opener. It even addresses how our two hemisphere characters are so different that each may actually manifest unique aches and pains that the other does not acknowledge or exhibit.

Moreover, if you are looking for an alternative tool in how you might manage mental health issues, Dr. Richard Schwartz’s Internal Family Systems model is an interesting strategy that recognizes and works with the different parts of a person’s personality so they can collaborate to find a healthy solution. Each of these books and tools is fascinating if you are interested in learning more about the brain.

Both of our cerebral hemispheres are constantly contributing to the whole of any experiential moment, so I do not mean to imply that either the left brain or the right brain functions in isolation. Modern technology shows clearly that at any moment in time, both hemispheres are contributing to the input, experience, and output of the nervous system. However, as I stated previously, brain cells dominate and inhibit their counterpart cells as a standard practice, so the brain is not all-on or all-off under any circumstance except for death.

As we think about how the brain works, it is natural to ask this question: “How is it possible that a group of brain cells can work together to create a personality at all?” I’m not the first person to ask this question, nor am I the first to experience a brain trauma, exhibit a change in personality, and then

recover the traumatized cells, regaining old circuits, old skill sets, and lost personality traits. However, I may be the first neuroanatomist to take this particular journey deep into the neural and psychological workings of my brain and then walk away with these unique insights concerning our Four Characters.

Brain cells are beautiful little creatures that come in many different shapes and sizes, and their design dictates their ability to perform their specific function. For example, the sensory neurons located in the primary auditory cortex of each of our hemispheres have a unique shape that supports their ability to process sound information. Other neurons that function to interconnect different regions in the brain have an appropriate shape for that action, as do the cells of the motor system.

Neuroanatomically, it is important to note that the neurons in your brain and how they connect with one another are essentially the same for all of us. Structurally speaking the bumps and grooves of the outermost cerebral cortex of everyone’s brain are virtually identical, so much so that damage to a specific area in your brain would wipe out comparably the same function as in mine, should I have the same trauma. Using the example of the motor cortex, if you and I experienced damage to the same specific group of cells in the same hemisphere, we would more than likely experience paralysis in the same parts of our bodies.

Underlying the functional differences between our two hemispheres are neurons that process information in unique ways. For example, the neurons in our left brain function linearly: they take an idea, compare that idea to the next idea, and then compare the by-product of those ideas to the next idea. Therefore our left brain has the ability to think sequentially. For example, we know that we need to start the engine before we put the car in gear. Our left hemisphere is an amazing serial processor that not only creates abstract linearity—as in 1+1=2—but manifests for us temporality, the linear sense of time whereby we can separate past, present, and future.

Our right-brain cells are not at all designed to create linear order. Instead, our right hemisphere functions like a parallel processor, bringing in multiple streams of data that simultaneously reveal a single complex moment of experience. Our right brain manifests a rich composite of the right here, right now present moment by adding depth to the creation of our memories, which are influenced by both of our hemispheres.

Although many of our brain cells are responsible for doing obvious things like understanding language or manifesting vision, other neurons function to create our thoughts or emotions. We use the term module to describe the way in which groups of neurons interconnect with one another in order to function together as an aggregate. Each of our Four Characters, for example, is supported by its specific and unique module of neurons.

When I experienced the hemorrhage in the left hemisphere of my brain, most of those cells simply went off-line because of the inflammation, swelling, and pressure buildup within my skull. In response to the trauma, the left-brain cells that had dominated my right-brain cells via the corpus callosum released their inhibition over those cells in my right brain, just as with the split-brain patients. When this occurred, the characters of my leftthinking and left emotional networks receded, while the comparable characters of my right brain’s thinking and emotional modules became untethered, unfettered, newly dominant, and free to run wild.

If you are curious about how I could recall the events that happened on the morning of the stroke, even with my left brain offline, it is important to note that although the circuits in my left brain shut down due to the trauma, I did not die, nor did I become unconscious. In addition, the stroke did not blow up—boom—and then it was all over. Instead, after the blood vessel in my left hemisphere exploded, over the course of four hours, more and more blood slowly oozed into that left-brain tissue, shutting circuits off as it went along. I experienced the stroke as more of a slow pipe leak than an instantaneous power outage. As a result, my right brain retained the ability to replay the memory of the morning of the stroke, much like a video.

By the time my left brain finally shut down completely, I had drifted into the peaceful consciousness of my right brain, where I lost all sense of urgency. Temporally, my right brain existed solely in the present moment, with no past regrets, present fears, or future expectations. From this, and the next eight years of recovery, it was apparent that the job of my right-brain circuitry was to process the experience of the right here, right now present

moment.

My left hemisphere, on the other hand, had functioned like a bridgeacross time : it was responsible for linking this present moment to the past moment and then to the next moment. Somehow those cells in my left brain were organized in such a way that I had been capable of linear thought.

Miraculously, my left brain understood that I needed to put my socks on before my shoes.

Clearly, we have two hemispheres for a reason, and without our left brain we are completely nonfunctional in the external world, in that we have no past or future, no linear thought, no language, and no sense of the boundaries of where we begin or end. Our left brain offers us our individuality, while our right brain connects us with the consciousness of not only the collective whole of humanity but the vast expansive consciousness of the universe.

By having both of these hemispheres working together inside of one head, we experience a natural duality. As a result, it is normal for us to endure an ongoing internal conflict, based completely on the two uniquely autonomous perspectives of our left and right brains. For example, my left brain might want to jump on that homework immediately and get it done, while my right brain would rather go out and play, leaving the work for the last minute.

THE FOUR CHARACTERS IN OUR BRAIN

The differences between the two hemispheres are far greater than simply the underlying anatomy, physiology, and resultant skill sets. My experience of losing my left brain and then rebuilding it over the course of eight years taught me that in addition to executing opposite abilities and constructing different realities, each of my two hemispheres is the home to very specific and predictable characters. These are the Four Characters you briefly met in the last chapter.

More specifically, with recovery, when I salvaged the functions of my left-brain thinking module (Character 1), with them came the goal-driven, well-organized, methodical, controlling character who had dominated my pre-stroke life. She was strong, powerful, capable, manipulative, good with time management, and completely judgmental. Following her recovery, she wanted to be the boss again inside my brain.

In addition, as this Left Thinking Character 1 regained its ability to process information linearly, as well as to judge things as right/wrong or good/bad, I recouped the ability to experience emotions that were dependent upon a memory from another place and time. For example, we have the ability to feel guilt or shame in response to something that has already occurred, or we can build up resentments over time, or seek revenge for something that has happened in the past. Once the emotional module of my left brain healed enough to come back online, I could experience these kinds of emotions again. But just as a strict and productive Character 1 came back online with my left-brain thinking tissue, a pained and cautious Character 2 came back online with my left-brain emotional cellular network.

I will admit that I truly enjoyed not having any of the pain from my past in my left-brain emotional module anymore, as I did not miss those tragic emotional circuits of my childhood. Yet having said that, life without the richness of deep emotions is a flat place to exist. This left-brain emotional Character 2 feels and knows our past pain, and it is this character that takes us right up to the edge of our potential growth and either pushes us over that edge or retreats us back into the safety of what feels familiar. I have to

know what is safe and not safe if I am to define the boundaries of my safety. I have to know what is right for me in order to know what is not right. I have to know darkness or sadness to recognize light or joy.

It is our left-brain emotional Character 2 who screams, wails, and rages against all those injustices that it has perceived as hurtful, dangerous, or unfair. It also holds us back, flees or freezes when something triggers our fear. Over the years, it has been the job of this tender and vulnerable character to hold our past pain in memory for our future protection. If we want to evolve into our best selves and live our best lives, we must create a healthy relationship with our left-brain Character 2. We grow and thrive when we are brave enough to stand in the center of our own pain and listen to what it is trying to communicate.

During my recovery, the newly dominant Right Thinking Character 4, who felt open, expansive, kind, and as big as the universe, was not too keen on letting the recovered stress-driven Character 1 of my left thinking brain waltz right back in to dominate my consciousness. Although I have to say I was thrilled to have those neural networks back in action, so I could speak and understand when others spoke to me and know the boundaries of my body again, I preferred embodying the never-ending peaceful gratitude of my Character 4’s open heart. That is why I consciously chose to remain right-brain dominant. And if I can choose which circuitry I want to run, so

can you.

As you move through this book, you will learn a great deal more about each of your Four Characters, what they feel like inside of your body, and how you, too, can choose who and how you want to be in any moment.

CHAPTER 3