The Neurobiology of Stress: the Human Brain and How It Responds to Stress
Posted Oct 17 2011 2:28pm
(Editor’s note: We are pleased to bring to SharpBrains readers a new 6-part series on the Neurobiology of Stress, excerpted from the recent book Nowhere to Hide: Why Kids with ADHD and LD Hate School and What We Can Do About It, by SharpBrains contributor Dr. Jerome Schultz .)
Understanding the Human Brain and How It Responds to Stress
Worry is like a rocking chair. It gives you something to do, but it gets you nowhere.
— Erma Bombeck
The brain is the control center for all of our thoughts, actions, attitudes, and emotions. It ’ s the pilothouse on the riverboat of our lives. It’s Mission Control for all of our ﬂ ights into space or time. It ’ s the air trafﬁc controller that helps us navigate and reroute our paths based on incoming and outgoing information and how we’re feeling about it at the time. It’s the John Williams of our personal symphony. It ’ s the Mother Ship to our Starﬂeet; it’s . . . (Uh, sorry, I got carried away there, but I think you get my point!)
As I was working on the drafts of this chapter, my own brain was very active, to say the least. I kept hearing in my head the words of the old Jack Scott favorite (#5 on the charts in 1960), asking me that musical question: “ What in the world’s come over you? ” The song also wondered if I could ever change my mind.
At ﬁrst I took this message from the deep memory stores of my brain to be a protective warning about the writing task upon which I had embarked. But alas, this melodious warning was, as they say, too little and too late. Madly typing away, I banished the tune from my head. I had an unquenchable desire to tell the story of the impact of stress in the lives of kids with LD and ADHD, not to mention the fact that I had a signed book contract sitting in a folder on my desk.
The cognitive and emotional centers of my brain collaborated nicely to keep my ﬁngers moving on the keyboard, but I understood why that song kept popping up. I was not without my own stress about writing this chapter. To say “I wrote the book on stress” is not the same as saying I had conquered it. (In fact, it ’ s a double — entendre. Get it? … I wrote the book while stressed . . . never mind.)
Seriously! How was I ever going to write an introduction to the brain, the most complex organ in the human body, that you, my reader, would want to read, and that you would understand?
Hundreds of thousands of textbooks and scholarly articles contained deep and dense discussions by brilliant scientists all over the globe who were trying to explain the mysteries of this incredible organ, and I had to do it in 70,000 words!
You’ ll learn in this book that the best way to combat stress is to gain some control over whatever it is that threatens you.
My own stress level began to go down dramatically as I realized I didn ’ t have to tell the entire story. I just needed to focus on the parts and systems of the brain that are most involved in the perception and processing of stress. As a neuropsychologist, I ﬁnd this part of the story incredibly interesting, and hope you will as well. Trying to tell the story of stress without putting it in the context of the brain is like writing a novel without giving the characters a setting in which to act out their dramas. Without context, the reader can’t see where the action is taking place.
This helps explain the perception of the many parents, kids, and even teachers who tend to view the behaviors that result from stress not as brain-based, brain-generated reactions but as premeditated oppositional or even deﬁant misbehaviors. Putting the characters of this story — the symptoms of stress — in the context of the brain and central nervous system makes it possible to understand their nature and their purpose in a way that makes scientiﬁc sense. So … stay with me as I set the stage for an amazing tale about how the brain deals with stress, and how the presence of neurologically based ADHD and LD put a special spin on the story.
THE HUMAN BRAIN: A BRIEF TOUR
To most people, the brain is terra incognita, a priceless piece of neurological real estate that we’re glad we own but tend to take for granted unless or until something bad happens to it. So let’s take a brief tour, just so you can appreciate the inestimable value of this miraculous organ called the brain. (If you ’ re very familiar with brain anatomy and function, you might want to skip this overview and move on to “The Stress Response Explained,” later in this chapter. You can always return to this section if subsequent reading reveals that you need a refresher.)
The average adult human brain weighs about three pounds (a kilogram and a half), which is a little bigger than a small cantaloupe or a large grapefruit, depending on the growing season. It starts out substantially smaller, of course, but as certain kinds of cells develop and change as a child moves into adulthood, the brain grows in size. As a result of myelination (the development of the outer coating of the long stem of brain cells, or neurons), and the proliferation of glial cells (the term glial comes from the Greek word for glue), which hold the brain together and feed it, an adult brain is about three times heavier than it was at birth. This is why you occasionally have to buy new hats.
The largest and most recognizable part of the brain is the large dome — shaped cerebrum, which is the outermost layer of brain tissue. If you lift off the skull and look down on the brain from above, it looks rather like what you see when you lift half the shell off a walnut. However, the cerebrum is not stiff like a nut; it has a thick, jelly-like consistency that allows it to literally bounce around inside the skull, which is why it ’ s so important to protect the head from encounters with immovable objects.
A sheet of neural tissue called the cerebral cortex forms the outermost surface of the cerebrum. It includes up to six layers, each one different in terms of the arrangement of neurons and how well they connect and communicate with other parts of the brain. The cortex is distinguishable by its many little ridges (called gyri) and valleys (sulci). In terms of space, the cortex is an economically arranged region that folds in on itself many times. This results in a very large but mainly hidden surface area that contains more neurons than any other part of the brain.
To Be Continued…
October 24th: Grey Matters
October 31st: The Little Brain Down Under
November 7th:Stress Response Explained
November 14th: The Human Brain Likes Balance
November 21st: To Fight, Flee or Freeze –That is the Question
– Jerome J. Schultz, Ph.D., the Author of Nowhere to Hide: Why Kids with ADHD and LD Hate School and What We Can Do About It (Jossey-Bass; August 2011), is a clinical neuropsychologist and is on the faculty of Harvard Medical School in the Department of Psychiatry. He served until recently as the Co-Director of the Center for Child and Adolescent Development, CCAD, a multi-disciplinary diagnostic and treatment clinic which is a service of the Cambridge Health Alliance, a Harvard Teaching Hospital.