Posts Tagged ‘brainstem’

Our Two Minds

March 8, 2018

There are two fundamentally different ways of knowing to construct our mental life. The rational mind is the mode of comprehension of which we are typically conscious. It is more prominent in awareness, thoughtful, able to ponder and reflect. There is another system of knowing which is alongside it. It is the emotional mind. The emotional mind is impulsive and powerful, if sometime illogical. This emotional/rational dichotomy resembles the folk distinction between “heart” and “head.” Knowing something “in your heart” is a different order of conviction that is somehow a deeper kind of certainty than thinking with your rational mind. In “Emotional Intelligence” Goleman writes, “There is a steady gradient in the ratio of rational-to-emotional control over the mind; the more intense the feeling, the more dominant the emotional mind becomes and the more ineffectual the rational. This is an arrangement that seems to stem from eons of evolutionary advantage to having emotions and intuitions guide our instantaneous response in situations where our lives are in peril—and where pausing to think over what to do could cost us our lives.”

Goleman continues, “These two minds, the emotional and the rational, operate in tight harmony for the most part, intertwining their very different ways of knowing to guide us through the world. Ordinarily there is a balance between emotional and rational minds, with emotions feeding into and informing the operations of the rational mind, and the rational mind refining and sometimes vetoing the inputs of the emotions. Still, the emotional and rational minds are semi-independent faculties, each, as we shall see, reflecting the operation of distinct, but interconnected, circuitry in the brain.”

Most of the time these minds are well coordinated with feelings being essential to thought, and thoughts to feelings. However, when passions surge the balance tips: it is the emotional mind that captures the upper hand, swamping the rational mind.

To understand the potent hold of emotions on the thinking mind it is useful to understand how the brain evolved. Human brains, with their three pounds or so of cells and neural juices, are about triple the size of those in our nearest cousins in evolution, the nonhuman primates. Over millions of years of evolution, the brain has grown from the bottom up, with its higher centers developing as elaboration of lower, more ancient parts. The growth of the brain in the human embryo roughly retraces this evolutionary course.

The most primitive part of the brain for all species that have more than a minimal nervous system is the brainstem surrounding the top of the spinal cord. This root brain regulates basic life functions like breathing and the metabolism of the body’s other organs, as well as controlling stereotyped reactions and movements.

The emotional centers emerged from the brainstem. Millions of years later in evolution, from these emotional areas the thinking brain or “neocortex” evolved. The fact that the thinking brain grew from the emotional reveals much about the relationship of thought and feeling: there was an emotional brain long before there was a rational one.

New, key layers of the emotional brain came with the arrival of the first mammals. Because this part of the brain rings and borders the brainstem, it was called the ‘limbic’ system, from “limbus,” the Latin word for “ring.” This new neural territory added emotions proper to the brain’s repertoire. When we are in the grip of craving or fury, head-over-heels in love or recoiling in dread, it is the limbic system that has us in its grip.

The limbic system refined two powerful tools, learning and memory, as it evolved. These advances allows an animal to be much smarter in its choices for survival, and to fine-tune its responses to adapt to changing demands rather than having invariable and automatic reactions.

About 100 million years ago, the mammalian brain took a great growth spurt. Piled on top of the thin two-layered cortex-the regions that plan, comprehend what is sensed, coordinate movement—several new layers of brain cells were added to form the neocortex. In contrast to the ancient brain’s two-layered cortex, the neocortex offered an extraordinary intellectual edge.

Our neocortex, so much larger than in any other species, has added all that is distinctly human. It is the seat of thought; it contains the centers that put together and comprehend what the senses perceive. It adds to a feeling what we think about it—and allows us to have feelings about ideas, art, symbols, imaginings.

This new addition to the brain allowed the addition of nuance to emotional life. Limbic structures generate feelings of please and sexual desire. The addition of the neocortex and its connections to the limbic system allowed for the mother-child bond that is the basis of the family unit.

So the neocortex provided the basis for sophisticated interactions among humans.
However, problems can emerge when the neocortex loses the upper hand. Consider a nuclear war. Here it would be clear that the neocortex had lost the upper hand to the emotional mind. And it is possible that the neocortex justified the launching of a nuclear war and the extinction of homo sapiens. Such irony!

© Douglas Griffith and, 2018. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Douglas Griffith and with appropriate and specific direction to the original content.