![]()
PART ONE: The Neurobiology of Stress
1
Stayinâ Alive
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.
âErma Bombeck
The brain is the control center for all of our thoughts, actions, attitudes, and emotions. Itâs the pilothouse on the riverboat of our lives. Itâs Mission Control for all of our flights into space or time. Itâs the air traffic controller that helps us navigate and reroute our paths based on incoming and outgoing information and how weâre feeling about it at the time. Itâs the John Williams of our personal symphony. Itâs the Mother Ship to our Starfleet; itâs ⌠(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: âWhat in the worldâs come over you?â 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 âI wrote the book on stressâ is not the same as saying I had conquered it. (In fact, itâs 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!
Youâll 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 didnât 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 canât 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 storyâthe symptoms of stressâin 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 weâre glad we own but tend to take for granted unless or until something bad happens to it. So letâs take a brief tour, just so you can appreciate the inestimable value of this miraculous organ called the brain. (If youâre very familiar with brain anatomy and function, you might want to skip this overview and move on to âThe Stress Response Explained,â 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 itâs 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.
Gray Matters
The term gray matter usually evokes an image of the cortex, because thatâs the part most visible in pictures of the brain. In fact, gray matter makes up not only the cerebral cortex but also the central portion of the spinal cord and areas called the cerebellar cortex and the hippocampal cortex. This dense tissue is packed full of neuronal cells, their dendrites (branching, root-like endings), axon terminals (the other end), and those sticky glial cells I mentioned earlier. The cortex is the area of the brain where the actual processing of information takes place. Because of its relative size and complexity, itâs easy to understand why it plays a key role in memory, attention, perceptual awareness, thought, language, and consciousness.
A Division of Labor
A central groove, or fissure, runs from the front to back of the cortex, dividing it into right and left hemispheres. In general, the left hemisphere controls functions on the right side of the human body and the right hemisphere controls the left side, but there are significant exceptions and much sophisticated interaction between the two hemispheres. This communication between the left and right hemispheres is facilitated by the corpus callosum, a wide, flat bundle of axons located in the center of the brain, beneath the cortex. Think of it as the Lincoln Tunnel, connecting Manhattan and Jersey City. (Iâll leave it to you to decide which one represents which hemisphere.)
The corpus callosum makes up the largest area of so-called white matter in the brain. White matter is made of bundles of axons each encased in a sheath of myelin. These nerve bundles lead into and out of the cortex and the cerebellum, and branch to the âold brain,â the hippocampus. About 40 percent of the human brain is made up of gray matter, and the other 60 percent is white matter. Itâs the white matter that facilitates communication between different gray matter areas and between the gray matter and the rest of the body. White matter is the Internet of our brains. (Al Gore did not invent it.)
Evolution, tempered by experience, has employed gray matter to build what might be considered very well-developed âcognitive condosâ that sit above the hippocampus. This arrangement is very important to a discussion of stress. Our old or primitive brain was primed for survival in our ancestorsâ environment. Itâs interesting to note that the brains of lower vertebrates like fish and amphibians have their white matter on the outside of their brain. We are blessed (and cursed) with lots of gray matter that gives us the ability to think things through (especially if we are anxious). Frogs and salamanders and their pond-side friends donât think about danger so muchâthey just get out of its way! (And while I canât be sure, I donât think that they have nightmares about giant human children armed with nets.)
How do you feel about that? In case you ever get this question on Jeopardy or in a game of Trivial Pursuit, the limbic system is made up of the amygdala, the hippocampus, the cingulate gyrus, fornicate gyrus, hypothalamus, mammillary body, epithalamus, nucleus accumbens, orbitofrontal cortex, parahippocampal gyrus, and thalamus. These structures work together to process emotions, motivation, the regulation of memories, the interface between emotional states and memory of events, the regulation of breathing and heart rate, the production of hormones, the âfight or flightâ response, sexual arousal, circadian rhythms, and some decision-making systems. Pretty impressive job description, eh? The word limbic comes from the Latin word limbus, which translates to âbeltâ or âborder,â because this system forms the inner border of the cortex. The limbic system is part of the old brain and developed first, followed by the new brain: the cortex, which is sometimes referred to as the neocortex. Put very simply, the limbic system feels and remembers; the cortex acts and reacts. And they communicate with each other. Why is this important? The limbic system figures prominently in whatâs called the stress response, which is a central player in this book.
These days, both our old and new brains are activated when weâre under stress. The primitive part, the limbic system (notably the hippocampus), sniffs out danger well before the new brain (the neocortex) actually processes it. The old brain responds first, acting as a sort of fire alarm system. It is the neocortex, and in particular, the frontal lobe (the prefrontal cortex), that helps us make sense of the alarms.
The cortex is made up of four major sections, arranged from the front to the back. These are called the frontal, parietal, occipital, and temporal lobes. Each of the four lobes is found in both hemispheres, and each is responsible for different, specialized cognitive functions. For example, the occipital lobe contains the primary visual cortex, and the temporal lobe (located by the temples, and close to the ears) contains the primary auditory cortex.
The frontal lobes are positioned at the frontmost region of the cerebral cortex and are involved in movement, decision making, problem solving, and planning. There are three main divisions of the frontal lobes. They are the prefrontal cortex, the premotor area, and the motor area. The frontal lobe of the human brain contains areas devoted to abilities that are enhanced in or unique to humans. The prefrontal cortex is responsible for planning complex cognitive behaviors, the expression of personality, decision making, and social behavior, as well as the orchestration of thoughts and actions necessary for a person to carry out goals. A specialized area known as the ventrolateral prefrontal cortex has primary responsibility for the processing of complex language. It is more commonly called Brocaâs area, named for a nineteenth-century French physician who determined its role.
In humans and other primates, an area located at the forward part of the prefrontal cortex is called the orbitofrontal cortex. It gets its name from its position immediately above the orbits, the sockets in which the eyes are located. The orbitofrontal cortex is very involved in interpreting rewards, decision making, and processing social and emotional information. For this reason, some consider it to be a part of the limbic system.
The amygdala, a part of the limbic system, is a brain structure that is responsible for decoding emotions, especially those the brain perceives as threats. As we evolved as a species, many of our alarm circuits have been grouped together in the amygdala. Not surprisingly, many regions of the brain send neurons into the amygdala. As a result, lots of sensory messages travel instantaneously to the amygdala to inform it of potential dangers lurking in our neighborhood. The amygdala is our guard dog.
The amygdala is directly wired to the hippocampus, also a part of the limbic system. Since the hippocampus is involved in storing and retrieving explicit memories, it feeds the amygdala with strong emotions triggered by these recollections. Why is this important? If a child has a negative experience in school, like being terribly embarrassed when asked to read in front of the class, the hippocampus just wonât let go of this memory, and it shouts it out to the amygdala. Since the amygdala has signed a no confidentiality agreement, it sends a warning to the rest of the brain to go into protection mode. A rather amazing arrangement, donât you think?
Whatâs really interesting about this is that the hippocampus specializes in processing the context of a situation. As a result, the child under stress generalizes the entire situation and uses it as justification for anxiety or stress: âHey, theyâre telling me to go to social studies class.â Even though not everything about social studies may be a threatâperhaps just the fact that they read out loud in thereâthe hippocampus sends out a general alert. So the student responds by protesting the whole enchilada: âNo way Iâm going there.â
The amygdala is also wired to the medial prefrontal cortex. Want to know why this is important? This is the area of the brain that seems to be involved in planning a specific response to a threat to safety. Hereâs how it works: the child is hit with the gigantic Titanic news (which may be just âsocial studies coming up nextâ to the rest of the group, but itâs âSubmerged iceberg ahead!â to the kid worried about perceived horrors there). This two-way communication between the prefrontal cortex and the limbic system (particularly the amygdala) enables us to exercise conscious control over our anxiety. The emotion-cognition connection allows us to feel that we can do something about the danger that lies ahead. The child is then faced with the necessity of choosing a course of action that looks best for getting out of danger. This seems very protective but tends to be counterproductive, because the very mechanism that allows us to create an escape plan can actually create anxiety. âOh crudânow we have to do something!â The brain not only allows us to imagine a negative outcome, which can help us avoid danger, it makes it possible for us to imagine dangers that do not actually exist. This is a problem for children who have ADHD, and a huge problem for students who have both anxiety disorders and ADHD. If you do a brain scan of a person with ADHD while putting on pressure to perform in a certain way, you see that this âto doâ order results in a decrease in activity in the prefrontal cortex (instead of increasing it, as it ...