We now understand that the hippocampus set-point that modulates the adrenal’s production of cortisol is programmed very early in life. Thus, trauma at a young age increases the hippocampus’s sensitivity to cortisol. And this sets the stage for an ever-increasing decline in hippocampal function in adulthood, which inhibits our ability to respond to situations in novel ways.
Researchers have wondered if intervention could perhaps lower cortisol levels. If stress raised cortisol, they reasoned, then perhaps living a nonstressful life could lower it. The pioneering work in this area was carried out by the late psychoneuroendocrinologist Seymour “Gig” Levine, beginning in 1962. His groundbreaking research demonstrated that when laboratory guinea pigs were lovingly handled as pups, their cortisol secretion was diminished and this reduction persisted into adulthood.
Levine’s early experiments paved the way for countless other researchers who tested a variety of animals, including primates, to reaffirm that positive emotional experiences can provide protection to the delicate hippocampus by reducing cortisol production. While the set-point of hippocampal control of adrenal cortisol production may be genetically determined, we now understand that all positive and negative life experiences, whether in childhood or adulthood, can reset that sensitivity.
So we need not run off to a secluded cabin in the woods to ensure a stress-free life, appealing as this may be. For, as many of us have discovered, we take our ghosts and demons with us wherever we go, and our dramas become like the story of the traveler who meets a fellow traveler on the road, going the opposite direction, and asks him what the people were like in the city he is going to. The first traveler responds by asking him what the people were like in the city he just left. “It was full of thieves and liars. There was not a decent person in the town,” he states. To which the other traveler replies, “It will be exactly the same in the next town.”
The ongoing biochemical assault from stress hormones on our hippocampus makes it impossible to heal from emotional trauma. Like the second traveler above, everywhere we go seems to be populated by liars and thieves. But this can also be a beneficial signal. When we feel imprisoned by our toxic emotions, we know at some core level that we must heal our lifelong trauma. We know that in order to regain our sanity and discover new behaviors, we must change.
While the destructive emotions associated with past traumas, whether real or imagined, may tend to dominate your moods, you are nevertheless capable of developing neural networks that allow you to think and feel differently. You have the ability to experience events without letting the past cast them in a negative light. Once the limbic brain is enlisted to serve the greater brain synergy, you begin to establish new neural networks for joy, well-being, and creativity.
The Positives of Stress
But we must remember that stress isn’t all bad. In fact, it is essential for all human progress, just as necessity is the mother of invention. When we are unable to respond with creativity to a challenging situation, it is because we are caught in a neural rut. Our brain’s wiring won’t permit it. When you go to the gym for strength training, you put stress on your muscles, and at the end of the workout, you leave with a toned body and a feeling of accomplishment. Biological stress on a species, such as that caused by a change in food availability due to long-term drought, is resolved through creative coping or adapting. Without the stress of a changing ecosystem our apelike ancestors would never have left the savannas of Africa for more fertile areas in Asia and Europe; they would not have started walking on two legs instead of four. In those cases, stress was nature’s way of inviting the wisest and most adaptable to survive.
At our present point in human history, with a changing ecosystem and an increased toxic load from poisons in our food and water, our species is once again faced with the challenge of long-term survival. And the enlightenment required of us may be no less daunting than having to learn to walk upright on two legs.
This passage is excerpted from “Power Up Your Brain: The Neuroscience of Enlightenment,” by neurologist Dr. David Perlmutter and medical anthropologist Dr. Alberto Villoldo.
This article was originally published in the Fall 2011 issue of Brain World Magazine.
