What would it be like if you could put one hemisphere—one half of someone’s brain—to sleep and be able to have a conversation with just the other, awake hemisphere of their brain, all by itself?
And then reverse that and have another conversation with just the other half of their brain, all by itself? “Absolutely amazing!” is what I would say. That is what the Wada test does.
I first learned of the Wada Test back in 1994, and, please forgive my exuberance here,
I was absolutely blown away! This test was devised by Dr. Juhn Atsushi Wada, a Japanese-born, Canadian neurologist, just after World War II while he was still in Japan. He is today a highly respected leader in epilepsy research.
When considering neurosurgery to cure severe epilepsy, doctors perform a number of pre-operative evaluations as part of their planning for the surgery itself. Since the mid-1960s, the Wada test has been used as one of those pre-operative procedures for a surgery called a cerebral commissurotomy, where the corpus callosum is severed. The corpus callosum is a thick bundle of fibers, more than 200 million of them, located between the hemispheres and connecting the right hemisphere of the brain with the left hemisphere. From this central position, between the hemispheres, these fibers reach deep into both hemispheres connecting the neurons of the left hemisphere with those in the right hemisphere.
The “Split Brain”
Patients who have had this procedure done are called, among the cognitive neuroscientists who study them, “split brain patients.” These patients provide rare insight into the asymmetries, or differences between the left and right hemispheres of the human brain. At the forefront of these pioneering cognitive neuroscientists were Roger Sperry (1981 Nobel prize-winner, b. August 20, 1913 – d. April 17, 1994), Joseph Bogen (July 13, 1926 – April 22, 2005), and Michael Gazzaniga.
I will present future articles, bringing together information from many sources on the fascinating subject of the “split brain” and its relevance to a “two personality” view of the mind.
Information—and even inner conversations—are passed back and forth between the
hemispheres through the corpus callosum. This surgery is irreversible, a patient’s right hemisphere will never again know what their left hemisphere is thinking, and vice versa, so doctors only consider it as a last resort for curing intractable epilepsy.
So now, what does this amazing test do and how does it work? The Wada test determines which hemisphere has the ability to talk and which hemisphere has the greater memory capability. It has long been known that speech capability resides only in the left hemisphere for most—but not all—people, about 95% of right-handers and 70% of left-handers. This is important information for neurosurgeons. During neurosurgery, they want to know exactly which hemisphere has speech capability and where the areas of greatest memory capability are, so they can avoid causing inadvertent damage to speech or memory function.
That all said, now the fascinating part—how does it work and what is its relevance to the “two personality” view?
A doctor injects sodium amobarbital into one carotid artery supplying blood to the same-side hemisphere of the brain, putting it to sleep, leaving the other hemisphere awake. Typically, just prior to the injection, the doctor asks the patient to raise both arms and begin counting out loud.
If the injection is to the right hemisphere, within a few seconds, the left arm drops (the right hemisphere controls the left side of the body), and typically, after a small pause in counting out loud, the patient is able to continue counting. This indicates the right hemisphere is now asleep, and the awake left hemisphere has speech capability indicated by the continued counting. The anesthetist keeps the right hemisphere asleep for about 5 minutes or more while another doctor asks a protocol of questions of the awake, left hemisphere.
Then, later the same day or the next day, the procedure is reversed, injecting the left carotid artery, putting the left hemisphere to sleep. The doctor asks the same questions of the awake, right hemisphere. This time, the right arm will drop, and the counting will typically stop completely, indicating the left hemisphere is asleep and the awake right hemisphere does not have speech capability. However, the right hemisphere does have its own conscious awareness and does understand what is spoken to them. It can formulate answers, but just cannot speak them. Doctors use a pointing system for them to communicate their answers.
To see Dr. Wada Performing a Wada Test, <<<click on the link to the left.
Amazingly, a small percentage of people—about one and a half percent and always left-handers—will have speech capability in both hemispheres, and doctors can get verbal answers during both the first and the second Wada test. Also amazing, some, mute-for-speech right hemispheres can still sing, however.
Another noteworthy result of some Wada tests is the opposite emotional response of each hemisphere during its “awake” turn in communicating with the doctors. These phenomena of opposite emotional responses occur frequently enough during Wada testing that doctors have a name for them, “catastrophic dysphoric reaction” and “indifferent euphoric reaction.” 1
In these cases, most often when left hemisphere is asleep, the still “awake” right hemisphere expresses dysphoria that could include sadness, crying, despair, worry, guilt, or concern for their future or that of their relatives.2 Then, during the right side injection, the patient, with their “awake” left hemisphere, shows no such concerns and displays a neutral to positive sense of well-being.
When I first started my research on the “split brain” in 1994, and came across the Wada test, I was utterly amazed that “you could even do that”—put one hemisphere to sleep and communicate with the other as a separate entity. It became quickly clear that the nature of the consciousness of the left hemisphere in an individual was quite different—of a different order than that of their right hemisphere.
This intuitively fit with the work I had already been doing for five years with some of my clients suffering with intrapersonal conflict. They seemed to have a “part” of themselves that was more expressive, affective (emotional), impulsive, with liberal use of colloquialisms (e.g., instead of saying, “He said some things that upset a number of people,” a colloquial equivalent would be, “He was a complete ass!”). They inhibited that part when initially communicating with me.
Their demeanor, when inhibiting, was calm, deliberate, articulate, free of colloquial speech, and often sprinkled with the use of the 2nd person pronoun “you” when obviously referring to themselves. For example, “Whenever you do a job, you need to do it right”.
Occasionally, the more expressive part would “slip out.” When I would point out the difference in their communication, they would immediately revert to the calm, deliberate manner of communicating. Sometimes, when I pressed them on what they had just said, they would deny they meant what had just slipped out. For example, “Well, it’s not that he is an ass, really, it’s just that he has communication issues.” This cycle of “slip out, deny” would repeat itself during the conversation.
It was clear to me something strange and puzzling was going on. It was like I was communicating with “two separate people” with significantly different viewpoints and communication styles. And, I confess, I sometimes found it irritating, until I began recognizing I was dealing with a “repressive” form (there are four basic forms) of intrapersonal conflict. Colloquialisms spoken with “emotional content” are communications from the right hemisphere of the brain—right hemisphere wanted to be heard.
When I started using a “two personality” model as an educational tool with these difficult clients by describing it to them, that model mapped perfectly onto their internal experience of themselves. They “saw” themselves exactly within that model, often saying, “That’s it, that’s how it works with me.”
Then, when I began helping them integrate their two communication styles—their two personalities—through a comprehensive method I call a “Split Circuitry Integration,” my “success rate” with these folks took a big leap forward. During my work with these clients, teaching them about the Wada test was one piece of the puzzle to better understanding themselves and the structural, anatomical basis of their inner conflict. They, too, were amazed, just as I was back in 1994. But for many, there was also a profound and emotional sense of relief at discovering a sensible, coherent explanation—other than that they were crazy or defective—for their inner experience.
If the brain is an integrated single personality, how is it possible for each hemisphere of the brain to have dramatically different emotional reactions—a catastrophic dysphoric reaction and an indifferent euphoric reaction—within some minutes, hours, or one day of each other during Wada testing?
Granted, the majority of patients undergoing Wada testing suffer from epilepsy, and that could be a factor, but what that factor would be is not known. Granted, these patients know they are facing some serious neurosurgery, which could explain “catastrophic dysphoric reaction,” in one hemisphere. Yet how does that explain the “indifference euphoric reaction” noted in the other hemisphere of the same patient?
Some epileptics suffer from Interictal Dysphoric Disorder (IDD), mood changes between seizure events, and someone may try to make a connection there. Nothing I have found so far explains this dysphoric/euphoric reaction occurring with some patients during Wada testing. It is an anomaly I think is important.
My question still stands. Are these Wada test results a clue worthy of including in any discussion of the possible truth that there are two distinct, independent, self-determined personalities in every human being, each residing in its own hemisphere of the brain?
Yes, absolutely. Do Wada test results prove this thesis? Absolutely not. They are one clue requiring more converging evidence from other research in order to begin seriously including Wada testing as evidence supporting the “two personality” view.
Did you know that the two hemispheres within one person can get into a physical altercation with each other? True examples of this violence are found in the accepted annals of neuroscience. In future articles I will present more of that converging evidence from the amazing and fascinating world of “split brain” research.
What are the implications of the “two personality” view? If true, then problematic intrapersonal conflict, or more simply, painful inner conflict, is the only psychological malady known whose root cause can be traced to a natural structural configuration in the anatomy of the brain, that enables it. It maps perfectly onto the inner experience of those who suffer with it. If widely known, this “two personality” model could bring relief to millions experiencing problematic inner conflict who secretly, and ignorantly believe they are “flawed.”
Final note: I am a professional expert in intrapersonal conflict with years of successful experience and results with close to two thousand clients suffering from painful inner conflict. It is my passion. I am not a doctor, nor do I have an advanced degree in neuroscience or neuroanatomy. I am an aficionado and enthusiastic student of “split brain” research as it applies to the “dual personality” view. As a non-scientist, I have a willingness to be wrong, and with compelling new evidence, I may change certain of my views, but I will ever grow them to get closer and closer to some truth.
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2 S.P. Springer and G. Deutsch, “Emotional Responses to Hemispheric Injuries,” Left Brain, Right Brain: Perspectives from Cognitive Neuroscience, 5th Edition (New York: W.H. Freeman and Company, 1998)