Our most primitive instincts reside at the root of the limbic system, in the most ancient, no-frills portion of the brain. There a core of barbed neurons meanders along the brain stem. It is this archaic system that serves the functions of maintaining constancy in the internal milieu and modulating states of arousal. One little nick in this sloppy web of twisted barbed wire, and we find ourselves in an irreversible coma. When it was announced that President Kennedy had been shot and had sustained an injury to his brain stem, my group of research assistant colleagues in James Old’s neurophysiology lab wept as we sat by the television in the University of Michigan student union, realizing that the end had come to our Prince of Camelot.
The neuroanatomist Walle Nauta aptly called the primal brain stem regulation of arousal “the posture of the internal milieu.” With this descriptive connotation, he acknowledged, validated and updated the prophetic work from the previous century of the father of modern physiology, Claude Bernard. Bernard had shown how the primary requirement of all life is the maintenance of a stable internal environment. Whether one is considering a cell, an amoeba, a rock star, a custodian, a king, an astronaut or a president, without this dynamic internal stability in the face of an ever-changing external environment, we would all perish. For example, the oxygen levels and ph (acidity) of the blood must be kept within a very narrow range for life to remain viable. It is the brain stem, through a myriad of complex reflexes, that is “control central” responsible for the minutiae of constant adjustments that are required for the basic maintenance of life. This also includes the regulation of our basic states of arousal, wakefulness and activity. And as messy and primitive as the brain stem reticular activating system is, it does its assigned job of preserving life magnificently.
When compared with the obsessively neat, six-layered columnar organization of the grand cerebral cortex, the brain stem appears a lowly chaotic mess. However, it is just this primitive organization that allows it to carry out its assigned function. It quickly and efficiently gathers diverse sensory data from both inside and outside of the body and keeps the inside relatively stable in the face of a restless and capricious external milieu. At the same time, it collects and summates these various sensory channels to augment the overall state of arousal. This is why the noise of a passing truck can abruptly rouse us from slumber, or why stimulating a comatose patient with music, smells and touch may help return him to the land of the living. Nature has discovered that the modulation of arousal is best served through the nonspecific synesthesia of sights, sounds, smells and tastes in addition to the specific function of the various sensory channels.
As Below, So Above
Pre-mental consciousness remains as long as we live the powerful root and body of our consciousness. The mind is but the last flower, the cul-de-sac.
—D. H. Lawrence, Psychoanalysis and the Unconscious
The apparent opposition and dominance by the military order of the intricate six-layer cerebral cortex, over the messy anarchistic networks of the “simple- minded” brain stem, was upset by the great Russian-born neuropathologist Paul Ivan Yakovlev. In a seminal 1948 paper, this protégé of Ivan Pavlov challenged the hierarchical (top-down) Cartesian worldview and proposed that just as phylogeny begets ontology, the central nervous system structures, and by implication our increasingly complex behaviors, have evolved from within to outward, from below to above.
The innermost and evolutionarily most primitive brain structures in the brain stem and hypothalamus (the archipallium) are those that regulate the internal states through autonomic control of the viscera and blood vessels. This most primitive system, Yakovlev argued, forms the matrix upon which the remainder of the brain, as well as behavior, is elaborated.
The next level, the limbic system (the paleopallium or paleomammalian brain in terms of evolution and location), is a system related to posture, locomotion and external (i.e., facial) expression of the internal visceral states. This stratum manifests in the form of emotional drives and affects. Finally, the outermost development (the neopallium or neo-cortex), an outgrowth of the middle system in YakovIev’s schema, allows for control, perception, symbolization, language and manipulation of the external environment.
Though we identify primarily with the later, more sophisticated elaboration, Yakovlev emphasized that these brain strata (residing concentrically one within the other—much like Russian nesting dolls) are not functionally independent. Rather, they are overlapping and integrated parts that contribute to the organism’s total behavior. The limbic system and neocortex are rooted in the primitive (visceral) brain stem and are elaborations of its function. It was Yakovlev’s contention that the appearance of the more complex and highly ordered cerebral cortex is an evolutionary refinement—ultimately derived from emotional and visceral functions including ingestion, digestion and elimination. One could say that the brain is a gadget evolved by the stomach to serve its purposes of securing food. Of course one could also argue that the stomach is a device invented by the brain to provide it with the energy and raw materials it needs to function and stay alive. So whose game is it, body or brain? Of course, both arguments are equally true, and this is how organisms function. The brain implies the stomach and the stomach implies the brain; they are mutually intertwined in this democratic web of reciprocity. This organismic view turns on its head the Cartesian, top-down model where the “higher” brain controls the “lower” functions of the body, such as the digestive system. This difference in perspective is not just wordplay; it is rather a wholly different worldview, an entirely different outlook on how the organism works. It is here that Yakovlev has provided a map that modern-day neuroscientists could do well to incorporate into their thinking—that of a deeper appreciation for the organismic welding of a body-brain.
In summary, then, the tendency toward encephalization (according to Yakovlev) is a refinement of the evolutionarily primitive needs of visceral function. Thoughts and feelings are not new and independent processes divorced from visceral activity; we feel and think with our guts. The digestive process, for example, is originally experienced as physical sensations (pure hunger), then as emotional feelings (e.g., hunger as aggression) and finally as cortical refinements in the form of assimilating new perceptions and concepts (as in the hunger for and the digestion of new knowledge). Less flattering to our egocentrism, this (r)evolutionary “bottom-up” perspective focuses on an archaic, homeostatic, survival function as the template of neural organization and consciousness. Our so-called higher thought processes, of which we have become so enamored, are servants rather than masters.
The matrix of function and consciousness, Yakovlev’s sphere of visceration, is in the primitive reticular formation. His methodical analysis of thousands of slices of brain tissue (histology) yielded a poetic vision in the great traditions of his countrymen, Tolstoy and Dostoyevsky. Yakovlev delicately summarized his meticulous, lifelong investigations with the single encompassing statement, “Out of the swamp of the reticular system, the cerebral cortex arose, like a sinful orchid, beautiful and guilty.” Wow … wow … wow!
A Personal Pilgrimage
When I first encountered the ideas of Yakovlev, I registered the truth of his hypothesis viscerally. My gut rumbled in recognition; my emotions soared in excitement. And intellectually, I yearned to digest and savor the exquisite essence of this man’s genius.† I wanted to devour him alive—that is, if he was still alive. It took several days of persistent phone calls to locate him. He was indeed alive and well. This coming-of-age odyssey mutated to locating and meeting with some of my other key intellectual heroes. After finally receiving my doctorate from University of California–Berkeley in 1977, I sent copies of my thesis on stress to several scientists who were my intellectual mentors. This list included Nikolaas Tinbergen, Raymond Dart, Carl Richter, Hans Selye, Ernst Gellhorn, Paul MacLean and Yakovlev himself. I was on my way …
Yakovlev’s lab was in the basement of a dark cavernous building belonging (I
believe) to the National Institutes of Health. I proceeded toward the door described to me by the receptionist. It was ever so slightly ajar. As I poked my head in, I was startled by the panoramic vision of shelf after shelf filled with bottles of pickled brains. An impish figure called out, motioning me to his desk. This octogenarian of small stature had a quiet and gentle presence belying his truly expansive character. With twinkling blue eyes and genuine enthusiasm, Yakovlev warmly invited me to sit down. He proceeded to ask me about my interests and was curious why I might have chosen to come so far to visit him.
When I told him about my interest in instincts and about my ideas concerning mind-body healing, stress and self-regulation, he jumped up, grabbed my arm excitedly and took me from jar to jar sharing with me his vast variety of specimens, demonstrating the basic anatomical building blocks of the brain. From there he led me back to his desk and microscope; together we looked at slides of minutely thin slices of brain tissue. He narrated this viewing, waxing lyrical in his elaborate reasoning, as I imagined Darwin might have done in his laboratory a mere hundred or so years earlier. For me, the thrill was so intense that I felt as though I could not contain my pressing urge to jump up and shout, “Yes!” I knew that I was on the right track, that we truly are, to the last of our neurons, just a bunch of animals—and that’s really not so bad.
At one o’clock, after sharing an egg salad sandwich, Yakovlev drew me an intricate map to guide me to my next appointment, which was about forty miles into the Maryland countryside. He did this task in anatomical detail, meticulously employing a set of brightly colored pencils and dissecting, with exacting precision, the best route and its distinguishing landmarks. He offered that if I had time at the end of the day, I was welcome to return by the same route.
I arrived at my destination right on schedule. Paul MacLean greeted me politely but without the exuberant warmth that had been lavished upon me at my prior appointment. He did, however, ask me the very same question—why I had come so far to see him. I repeated the same answer. MacLean looked at me with a puzzled expression, combining both curiosity and a seemingly paternal concern. “That’s all very interesting, young man,” he offered, “but how do you expect to support yourself?” Feeling somewhat dejected, I asked him many questions about his twenty years of rigorous experimental study of what is now called the triune brain theory. MacLean had associated many specific behaviors suggested by the neuroanatomical pathways laid down by Yakovlev, Nauta and Papez. Although these fundamental brain types show great differences in structure and chemistry, all three intermesh and are meant to function together as a unitary (“triune”) brain. MacLean demonstrated methodically that not only did our neuroanatomy evolve as an elaboration, from the most primitive to the most refined and sophisticated, but (as Darwin would have predicted) so did our behaviors. The implications of this are beyond profound. They tell us that as much as we may not want to admit it, most primitive forms of our ancestral past dwell, latently, deep within us today (see Figure 11.1).124
The Paul MacLean Triune Brain Model
Figure 11.1 This figure illustrates the basic functions of the reptilian (brain stem), paleomammalian (limbic) and primate (neocortex) levels.
The eminent psychiatrist Carl G. Jung presciently recognized the need for the integration of our instinctual layering through the process of psychological individuation. He believed that in the assimilation of what he called the collective unconscious, each person moves toward wholeness. Jung understood that this collective unconscious was not an abstract and symbolic notion, but rather a concrete physical/biological reality:
This whole psychic organism corresponds exactly to the body, which, though individually varied, is in all essential features the specifically human body [and mind] which all men have. In its development and structure, it still preserves elements that connect it with the invertebrates and ultimately with the protozoa. Theoretically, it should be possible to “peel” the collective unconscious, layer by layer, until we came to the psychology of the worm, and even of the amoeba.125
Jung’s mentor, Sigmund Freud, also struggled with the implications of our phylogenetic roots in his seminal work, The Ego and the Id. With disarming honesty and ruthless self-examination, he challenges the basic assumptions of his life’s work. He states that “with the mention of phylogenesis, fresh problems arise, from which one is tempted to draw cautiously back … But there is no help for it,” he bemoans. “The attempt must be made—in spite of the fact that it will lay bare the inadequacy of our whole effort.” Clearly, Freud was questioning the basic validity and premise of his entire psychoanalytic foundation in the light of our phylogenetic heritage. Here he acknowledges the need to incorporate an understanding of our animal roots into the therapeutic process—but how? Yakovlev and MacLean give us just this underpinning.
As did Yakovlev before him, MacLean divided the mammalian brain into three distinctly organized strata, corresponding roughly to the reptilian archipallium, the paleomammalian and the neomammalian epochs of evolutionary development. MacLean developed this map to include the hypothalamus as nodal in the relations between the three brain regions—a driver at the wheel of the brain stem, regulating autonomic nervous system outflow. Drawing on the earlier work of W. R. Hess126 (who shared the 1949 Nobel Prize in Physiology or Medicine with the Portuguese neurologist, and ambassador to Spain, Egas Moniz), MacLean and Ernst Gellhorn127 argued that this primitive, pea-sized organ, the hypothalamus, organizes alternative courses of behavior. It directs the behavior of the organism as a whole, a job conventionally ascribed to the neocortex. As we shall see, the control of behavior is shared by various systems throughout the brain—there being no single locus of control. We have not a tripartite brain (containing three separate parts) but a triune brain, as MacLean called it, emphasizing the holistic integration of its parts. With our three brains (actually four if you include the aquatic—homeostatic—component we share with fish), we are presented with the Herculean task of being “of one mind,” a challenge that is both confining and liberating.
Three Brains; One Mind
The striving and territorial protectiveness of the reptile,
the nurturing and family orientation of the early mammal,
the symbolic and linguistic capacities of
the neo-cortex may multiply our damnation or grace our salvation.
—Jean Houston (The Possible Human)
MacLean’s triune brain has a delicate balancing act to navigate in its triune rather than tripartite role. If you were to face the side of the head and slice the brain in half (providing what is known as the midsagittal view), you would observe a “mind be-lowing” fact. The very front of the brain, the prefrontal cortex, responsible for the most complex functions of human behavior and consciousness, curves all the way around the cranium, making a near U-turn and abutting, with intimate proximity, the most archaic parts of the brain stem, hypothalamus and limbic system. Neuroscience teaches that generally when two parts of the brain are in close anatomical closeness, it is because they are meant to function together. This makes it even more likely that the electrochemical signals will be reliably transmitted.
Descartes might have been utterly flabbergasted at such an intimate relationship between the most primitive and the most refined portions of the brain. Here we have the highest pinnacle of what it is to be human “in bed” (cheek to cheek) with the most primal and archaic vestiges of our animal ancestry. Descartes would have found no rhyme or reason to this physical arrangement. Had he ever speculated in real estate, where value is all about “location, location, location,” he might have been even more perplexed. In addition, as next-door neighbors, brain stem, emotional brain and neocortex must find a common language with which to communicate. Maintaining such an intimate relationship is analogous to the task of interfacing a Craig or IBM supercomputer at MIT with an ancient abacus at the Chinese grocery so that they operate together as one unit. Likewise, the lizard’s rudimentary brain and Einstein�
��s genius brain (the neocortex) must cohabitate and communicate in a coherent harmony. But what happens when this coexistence between instinct, feeling and reason becomes disrupted?
Phineas Gage, a railroad supervisor in 1848, was the first well-documented case of such a violent divorce. While he was blasting a tunnel near Burlington, Vermont, a three-foot-long spike called a tamping iron was propelled, bullet-like, through his skull. It entered near his eye socket, penetrating his brain, and exited through the crown on the opposite side of his head. To everyone’s amazement, Mr. Gage, minus one eye, “recovered fully.” Well, not quite … While his intellect functioned normally, the injury altered his basic personality. Before the accident, he was well liked by his employers and employees (the ideal middleman). However, the “new” Mr. Gage “was arbitrary, capricious, unstable and considered by those who knew him to be a foul-mouthed boor.” Lacking in motivation, he was unable to hold down a job and ended up drifting, including time spent in a carnival sideshow.‡ One longtime associate observed that “Gage was no longer Gage.” In addition, a Dr. John Harlow, his physician, poignantly, described him in this manner: “Gage has lost the equilibrium or balance between his intellectual faculty and [his] animal propensities.”
Fast-forward one hundred and forty years to Elliot, a patient of the eminent neurologist Antonio Damasio.128 This poor man was at the end of his rope, having burned bridge after bridge in his personal and professional life. Unable to hold a job, bankrupted by various business ventures with disreputable partners and slammed by a rapid succession of divorces, Elliot had sought psychiatric help. His referral to Damasio provided the opportunity for a thorough neurological workup. He passed one cognitive/intellectual test after another and even scored normal on a standard personality inventory. Even on a test purporting to measure moral development, he scored high and was still able to reason through a variety of complex ethical questions. However, something was clearly not “normal” with this man. Yet in his own words Elliot said, “And after all of this I still wouldn’t know what to do.” While being able to “think through” all manner of complex intellectual and moral dilemmas, he was unable to make choices and act accordingly. His moral computers were working, but his moral compass was not.
In an Unspoken Voice Page 28
