Select passages by Ron Carmichael from Spark: The Revolutionary New Science of Exercise and the Brain (John J. Ratey and Eric Hagerman)
My comments are bolded, where I can find them. I have far more notes from this book than are depicted here. These only go to about page number 70 in the book, it has hundreds of pages.
Please buy this book if you find the knowledge below to be worthy:
By the authors: To keep our brains at peak performance, our bodies need to work hard. In Spark, I’ll demonstrate how and why physical activity is crucial to the way we think and feel.
To keep our brains at peak performance, our bodies need to work hard. In Spark, I’ll demonstrate how and why physical activity is crucial to the way we think and feel. I’ll explain the science of how exercise cues the building blocks of learning in the brain; how it affects mood, anxiety, and attention; how it guards against stress and reverses some of the effects of aging in the brain; and how in women it can help stave off the sometimes tumultuous effects of hormonal changes.
a good beginning...
It was already known that exercise increases levels of serotonin, norepinephrine, and dopamine — important neurotransmitters that traffic in thoughts and emotions. You’ve probably heard of serotonin, and maybe you know that a lack of it is associated with depression, but even many psychiatrists I meet don’t know the rest. They don’t know that toxic levels of stress erode the connections between the billions of nerve cells in the brain or that chronic depression shrinks certain areas of the brain. And they don’t know that, conversely, exercise unleashes a cascade of neurochemicals and growth factors that can reverse this process, physically bolstering the brain’s infrastructure. In fact, the brain responds like muscles do, growing with use, withering with inactivity. The neurons in the brain connect to one another through “leaves” on treelike branches, and exercise causes those branches to grow and bloom with new buds, thus enhancing brain function at a fundamental level.
It turns out that moving our muscles produces proteins that travel through the bloodstream and into the brain, where they play pivotal roles in the mechanisms of our highest thought processes. They bear names such as insulin-like growth factor (IGF-1) and vascular endothelial growth factor (VEGF), and they provide an unprecedented view of the mind-body connection.
Right now the front of your brain is firing signals about what you’re reading, and how much of it you soak up has a lot to do with whether there is a proper balance of neurochemicals and growth factors to bind neurons together. Exercise has a documented, dramatic effect on these essential ingredients. It sets the stage, and when you sit down to learn something new, that stimulation strengthens the relevant connections; with practice, the circuit develops definition, as if you’re wearing down a path through a forest.
In order to cope with anxiousness, for instance, you need to let certain well-worn paths grow over while you blaze alternate trails. By understanding such interactions between your body and your brain, you can manage the process, handle problems, and get your mind humming along smoothly. If you had half an hour of exercise this morning, you’re in the right frame of mind to sit still and focus on this paragraph, and your brain is far more equipped to remember it.
Of course you should exercise, but I won’t be preaching here. (It probably wouldn’t help: experiments with lab rats suggest that forced exercise doesn’t do the trick quite like voluntary exercise.) If you can get to the point where you’re consistently saying to yourself exercise is something you want to do, then you’re charting a course to a different future — one that’s less about surviving and more about thriving.
can a brother get an amen?
Among one entire class of sophomores, only 3 percent were overweight, versus the national average of 30 percent. What’s more surprising — stunning — is that the program has also turned those students into some of the smartest in the nation.
naperville? (I did not know this, but I know two astonishingly exemplary youths from Naperville. NOW I know why they are so special!
physical activity sparks biological changes that encourage brain cells to bind to one another. For the brain to learn, these connections must be made; they reflect the brain’s fundamental ability to adapt to challenges.
it just keeps getting better...
The more neuroscientists discover about this process, the clearer it becomes that exercise provides an unparalleled stimulus, creating an environment in which the brain is ready, willing, and able to learn. Aerobic activity has a dramatic effect on adaptation, regulating systems that might be out of balance and optimizing those that are not — it’s an indispensable tool for anyone who wants to reach his or her full potential.
“I guess it’s OK,” says Michelle. “Besides getting up early and being all sweaty and gross, I’m more awake during the day. I mean, I was cranky all the time last year.”
at the end of the semester, they’ll show a 17 percent improvement in reading and comprehension, compared with a 10.7 percent improvement among the other literacy students who opted to sleep in and take standard phys ed.
The literacy students are split into two classes: one second period, when they’re still feeling the effects of the exercise, and one eighth period. As expected, the second-period literacy class performs best. The strategy spreads beyond freshmen who need to boost their reading scores, and guidance counselors begin suggesting that all students schedule their hardest subjects immediately after gym, to capitalize on the beneficial effects of exercise.
The essence of physical education in Naperville 203 is teaching fitness instead of sports. The underlying philosophy is that if physical education class can be used to instruct kids how to monitor and maintain their own health and fitness, then the lessons they learn will serve them for life. And probably a longer and happier life at that.
The New PE curriculum has been in place for seventeen years now, and its effects have shown up in some unexpected places — namely, the classroom. It’s no coincidence that, academically, the district consistently ranks among the state’s top ten, even though the amount of money it spends on each pupil — considered by educators to be a clear predictor of success — is notably lower than other top-tier Illinois public schools.
TIMSS has been administered every four years since 1995. The 1999 edition included 230,000 students from thirty-eight countries, 59,000 of whom were from the United States. While New Trier and eighteen other schools along Chicago’s wealthy North Shore formed a consortium to take the TIMSS (thereby masking individual schools’ performance), Naperville 203 signed up on its own to get an international benchmark of its students’ performance. Some 97 percent of its eighth graders took the test — not merely the best and the brightest. How did they stack up? On the science section of the TIMSS, Naperville’s students finished first, just ahead of Singapore, and then the North Shore consortium. Number one in the world. On the math section, Naperville scored sixth, behind only Singapore, Korea, Taiwan, Hong Kong, and Japan. As a whole, U.S. students ranked eighteenth in science and nineteenth in math, with districts from Jersey City and Miami scoring dead last in science and math, respectively.
My conviction, and my attraction to Naperville, is that its focus on fitness plays a pivotal role in its students’ academic achievements.
Anytime you got a personal best, no matter what it was, you moved up a letter grade.” And this led to the founding principle of the approach he dubbed the New PE: Students would be assessed on effort rather than skill. You didn’t have to be a natural athlete to do well in gym.
“We just do them within a fitness model.” Instead of being tested on such trivia as the dimensions of a regulation volleyball court, Naperville’s gym students are graded on how much time they spend in their target heart rate zones during any given activity.
Lawler heard me interviewed on the National Public Radio program The Infinite Mind, during which I referred to a protein that’s elevated during exercise as “Miracle-Gro for the brain.” Unbeknownst to me, Lawler began repeating the phrase in interviews of his own, including one with the director of a documentary film about obesity in America, Super Size Me (2004).
So I made the journey to Illinois, and as I sat with Lawler and Zientarski in the atrium of the Naperville Holiday Inn, I listened to them say things I never expected to hear from a couple of coaches. “In our department, we create the brain cells,” Zientarski says. “It’s up to the other teachers to fill them.”
Only 6 percent of U.S. high schools offer a daily physical education class.
how can this be?
The California studies don’t stand alone. In 2004 a panel of thirteen noted researchers in fields ranging from kinesiology to pediatrics conducted a massive review of more than 850 studies about the effects of physical activity on school-age children. Most of the studies measured the effects of thirty to forty-five minutes of moderate to vigorous physical activity three to five days a week. They covered a wide range of issues, such as obesity, cardiovascular fitness, blood pressure, depression, anxiety, self-concept, bone density, and academic performance. Based on strong evidence in a number of these categories, the panel issued a recommendation that schoolchildren should participate in one hour (or more) of moderate to vigorous physical activity a day. Looking specifically at academic performance, the panel found enough evidence to support the findings of the California studies, and it also reported that physical activity has a positive influence on memory, concentration, and classroom behavior. It didn’t specify gym class, but you can see how the students in Naperville are getting a healthy jump start.
Sports physiologist Craig Broeder, who conducted the fitness study in Naperville, remarks that students can choose from eighteen activities for gym. “One of the things that too many people forget is that you have to find something that allows a student to feel comfortable at excelling,” he says. “So that it feels like them when they’re doing it. When you only give a kid a limited option, like playing basketball, and you make it seem like punishment or boot camp, there’s no way he’s going to continue doing it. At Naperville, they give kids lots of options by which to excel; they design lifetime fitness activities.”
“If you ask people, What is it you want our graduates to be able to know and do when they leave high school?” Zientarski explains, “They’ll say, We want them to be able to communicate. We want them to be able to work in small groups. We want them to be able to problem solve. We want them to be risk takers. Where does that happen?” he asks, eyeballing his guests. “Science class? I don’t think so.”
Of the six areas that the FitnessGram measures, two seem to be particularly important in relation to academic performance. “Body mass index and aerobic fitness really stuck out in our regression equation,” Castelli says.
The electroencephalogram (EEG) showed more activity in fit kids’ brains, indicating that more neurons involved in attention were being recruited for a given task. “We see better integrity there,” Hillman explains. In other words, better fitness equals better attention and, thus, better results.
Jessie and her sister actually decided to go paddling the morning of the Prairie State Achievement Examination, the Illinois version of the Scholastic Aptitude Test (SAT). They were so confident in their preparation, and so attuned to how exercise helped them focus, that they were comfortable splashing around a cold pool right before an important exam. How many high school kids do you know who would do that? How many adults do you know who would do that? “When we showed up for the test, we were cold and wet,” recalls Jessie. “We walked into the classroom, and we were the only ones who were awake. We ended up doing pretty well.” They both scored 1400 out of a possible 1600
Every time I know that a whole bunch of tests are coming up — when I’m really stressed out — I think, OK, you know how to handle this. It’s definitely a relief to know that I have something to fall back on. If I didn’t have that, I’d probably just go eat or something. But I know that exercise will spike up my brain activity, and so I think, Just go do it. I wouldn’t know that if it weren’t for my gym class.”
What strikes me about Zientarski’s transformation from drill sergeant to sculptor of bodies, brains, and minds is how far he has been willing to go in redefining gym. For example, one of the most innovative changes he made at Central was to add a mandatory square-dancing class for freshman. It may not sound cutting edge, but the class is set up to use movement as a framework for teaching social skills — a wonderful idea on many levels. In the first few weeks of the class, all the students receive scripts to use as conversation starters with their partners, and everyone switches partners after each dance. As the course progresses, the students are given time to interact without the scripts, first for thirty seconds and building up from there. The final exam is based on how accurately the students remember ten facts about a partner after spending fifteen minutes chatting.
Some kids who are socially timid never get a chance to learn how to talk to people and make friends, so they retreat, especially from the opposite sex. By not being singled out or relegated to a special social skills class, Zientarski’s square-dance students get to practice how to talk and interact in a nontoxic setting. The activity serves both as a distraction and as a confidence builder. Some master the drill, and others merely break through their fears, but because everybody’s doing it, it’s less embarrassing. When I talk to colleagues about the Naperville revolution and tell them that kids are learning these kinds of social skills in gym class, the reaction I get is stunned silence — they are in awe, just as I was.
By having the structure, opportunity, and expectation, socially anxious students log in positive memories about the way to approach someone, how close to stand, and when to let the other person speak. Exercise serves as the social lubricant, and it’s crucial to this kind of learning because it reduces anxiousness. Their brains are primed by the movement, and they lay down circuits that record the experience, which at first may be painful but which becomes less so in the context of an experience shared by the entire class. It’s an intuitively brilliant way to bring kids out of their shells, at a poignant age when everyone feels self-conscious. Zientarski puts them all in the same boat and gives them the tools and encouragement to build up their self-confidence. The dancing makes the whole lesson work.
It’s offerings like this, I believe, that explain why so many parents in Naperville report that gym is their kids’ favorite class.
In 1999 McCord visited Naperville, came home, and transformed physical education in Titusville almost overnight. The district has twenty-six hundred students in one high school, one middle school, four elementary schools, and one early learning center. Titusville installed fitness centers in the secondary schools, bought heart rate monitors, and got the local hospital to help fund the TriFit diagnostics. Titusville even restructured the school day, adding ten minutes to the schedule and shaving time from academic classes to carve out time for daily gym. “It did not cost us a cent to do that,” McCord says, noting that it was an administrator’s suggestion. “And it’s a huge move with No Child Left Behind — everybody else is going in the other direction.”
Now Titusville’s secondary schools have climbing walls, and the fitness centers are brimming with the latest training technology, most of it donated. The Cybex Trazer, for instance, is a brand-new device that looks like an upright computer station where students chase flashing lights. There are also cycling trainers, which allow kids to race one another on video screens or cue up routes from the Tour de France and compete with virtual Lance Armstrongs. McCord has also reached out to the community, opening the schools’ fitness centers to members of the senior center. Within the schools, he’s invited teachers in other subjects to get involved: English students use the heart rate monitors during public speaking, and math students use the data to learn how to graph.
Since the program started in 2000, the standardized test scores of Titusville’s students have risen from below the state average to 17 percent above it in reading and 18 percent above it in math. Equally important are the psychosocial effects McCord has noticed: not a single fist fight among the 550 junior high kids since 2000.
During one such show-and-tell, as McCord led a group past the junior high’s climbing wall, he noticed a girl named Stephanie stuck about halfway up. Bookish and a little heavyset, she was on display for everyone to see her fail. But as her classmates noticed her struggling, they began cheering, “Go, Stephanie!” She made it to the top, and McCord spoke to her later. “She started to cry and couldn’t believe the other kids were cheering her on,” McCord recalls. “She said it helped her pull herself up.”
based on news that one PE4life school in the inner city reduced its disciplinary problems by 67 percent. At Woodland Elementary School in Kansas City, Missouri, nearly all of the students have subsidized meal programs. In 2005 the physical education staff expanded gym from one class a week to forty-five minutes a day, focused almost entirely on cardiovascular activity. In the span of one school year, the students’ fitness levels improved dramatically, and counselors reported that the number of incidents involving violence at Woodland decreased from 228 to 95 for the year.
as the schoolchildren grow up, a larger percentage will continue to move and be active. They’ll grab their kayak or bike instead of their Game Boy, and their minds and moods will be sharper for it.
WHEN THE STUDENTS in Titusville or in Naperville go for a mile run in gym, they are more prepared to learn in their other classes: their senses are heightened; their focus and mood are improved; they’re less fidgety and tense; and they feel more motivated and invigorated.
Glutamate is a workhorse, but psychiatry focuses more on a group of neurotransmitters that act as regulators — of the signaling process and of everything else the brain does. These are serotonin, norepinephrine, and dopamine. And although the neurons that produce them account for only 1 percent of the brain’s hundred billion cells, these neurotransmitters wield powerful influence. They might instruct a neuron to make more glutamate, or they might make the neuron more efficient or alter the sensitivity of its receptors. They can override other signals coming into the synapse, thus lowering the “noise” in the brain, or, conversely, amplify those signals. They can deliver signals directly, like glutamate and GABA, but their primary role is in adjusting the flow of information in order to fine-tune the overall balance of neurochemicals.
Serotonin, which you’ll hear a lot more about in later chapters, is often called the policeman of the brain because it helps keep brain activity under control. It influences mood, impulsivity, anger, and aggressiveness. We use serotonin drugs such as fluoxetine (Prozac), for instance, because they help modify runaway brain activity that can lead to depression, anxiety, and obsessive-compulsiveness. Norepinephrine, which was the first neurotransmitter scientists studied to understand mood, often amplifies signals that influence attention, perception, motivation, and arousal. Dopamine, which is thought of as the learning, reward (satisfaction), attention, and movement neurotransmitter, takes on sometimes contradictory roles in different parts of the brain. Methylphenidate (Ritalin) eases attention-deficit/hyperactivity disorder (ADHD) by raising dopamine, thus calming the mind.
I tell people that going for a run is like taking a little bit of Prozac and a little bit of Ritalin because, like the drugs, exercise elevates these neurotransmitters. It’s a handy metaphor to get the point across, but the deeper explanation is that exercise balances neurotransmitters — along with the rest of the neurochemicals in the brain. And as you’ll see, keeping your brain in balance can change your life.
a family of proteins loosely termed factors, the most prominent of which is brain-derived neurotrophic factor (BDNF). Whereas neurotransmitters carry out signaling, neurotrophins such as BDNF build and maintain the cell circuitry — the infrastructure itself.
Once it became clear that BDNF was present in the hippocampus, an area of the brain related to memory and learning, researchers set out to test whether it’s a necessary ingredient in the process.
The initial activity marshals existing stores of glutamate in the axon to be sent across the synapse and reconfigures receptors on the receiving side to accept the signal. The voltage on the receiving side of the synapse becomes stronger in its resting state, thereby attracting the glutamate signal like a magnet. If the firing continues, genes inside the neuron’s cell nucleus are turned on to produce more building material for the synapses, and it is this bolstering of the infrastructure that allows the new information to stick as a memory.
Say you’re learning a French word. The first time you hear it, nerve cells recruited for a new circuit fire a glutamate signal between each other. If you never practice the word again, the attraction between the synapses involved naturally diminishes, weakening the signal. You forget. The discovery that astonished memory researchers — and earned Columbia University neuroscientist Eric Kandel a share of the 2000 Nobel Prize — is that repeated activation, or practice, causes the synapses themselves to swell and make stronger connections. A neuron is like a tree that instead of leaves has synapses along its dendritic branches; eventually new branches sprout, providing more synapses to further solidify the connections. These changes are a form of cellular adaptation called synaptic plasticity, which is where BDNF takes center stage.
Early on, researchers found that if they sprinkled BDNF onto neurons in a petri dish, the cells automatically sprouted new branches, producing the same structural growth required for learning — and causing me to think of BDNF as Miracle-Gro for the brain.
BDNF also binds to receptors at the synapse, unleashing the flow of ions to increase the voltage and immediately improve the signal strength. Inside the cell, BDNF activates genes that call for the production of more BDNF as well as serotonin and proteins that build up the synapses. BDNF directs traffic and engineers the roads as well. Overall, it improves the function of neurons, encourages their growth, and strengthens and protects them against the natural process of cell death.
BDNF is a crucial biological link between thought, emotions, and movement.
Only a mobile creature needs a brain, points out New York University neurophysiologist Rodolfo Llinás in his 2002 book, I of the Vortex: From Neurons to Self.
“That which we call thinking is the evolutionary internalization of movement.”
As our species has evolved, our physical skills have developed into abstract abilities to predict, sequence, estimate, plan, rehearse, observe ourselves, judge, correct mistakes, shift tactics, and then remember everything we did in order to survive.
Take the cerebellum, which coordinates motor movements and allows us to do everything from returning a tennis serve to resisting the pull of gravity. Starting with evidence that the trunk of nerve cells connecting the cerebellum to the prefrontal cortex are proportionally thicker in humans than in monkeys, it now appears that this motor center also coordinates thoughts, attention, emotions, and even social skills. I call it the rhythm and blues center. When we exercise, particularly if the exercise requires complex motor movement, we’re also exercising the areas of the brain involved in the full suite of cognitive functions. We’re causing the brain to fire signals along the same network of cells, which solidifies their connections.
When we learn something, a wide array of connected brain areas are called into action. The hippocampus doesn’t do much without oversight from the prefrontal cortex. Broadly speaking, the prefrontal cortex organizes activity, both mental and physical, receiving input and issuing instructions through the brain’s most extensive network of connections. The prefrontal cortex is the boss. As such, it is responsible for, among other things, keeping tabs on our current situation through so-called working memory, inhibiting stimuli and initiating action, judging, planning, predicting — all executive functions. As the CEO of the brain, the prefrontal cortex has to stay in close contact with the COO — the motor cortex — as well as many other areas.
The hippocampus is something like the cartographer, receiving new input from working memory, cross-referencing that information with existing memories for the sake of comparison and to form new associations, and reporting back to the boss.
A memory, scientists believe, is a collection of information fragments dispersed throughout the brain. The hippocampus serves as a way station, receiving the fragments from the cortex, and then bundling them together and sending them back up as a map of a unique new pattern of connections.
Brain scans show that when we learn a new word, for example, the prefrontal cortex lights up with activity (as does the hippocampus and other pertinent areas, such as the auditory cortex). Once the circuit has been established by the firing of glutamate, and the word is learned, the prefrontal cortex goes dark. It has overseen the initial stages of the project, and now it can leave the responsibility to a team of capable employees while it moves on to new challenges. This is how we come to know things and how activities like riding a bike become second nature. Patterns of thinking and movement that are automatic get stored in the basal ganglia, cerebellum, and brain stem — primitive areas that until recently scientists thought related only to movement. Delegating fundamental knowledge and skills to these subconscious areas frees up the rest of the brain to continue adapting, a crucial arrangement.
exercise elevates Miracle-Gro throughout the brain.
BDNF: Brain Derived Neurotrophic Factor (what the brain makes so you are able to acquire knowledge )
the hippocampus is an area of the brain that is extremely vulnerable to degenerative disease and that is needed for learning.
By showing that exercise sparks the master molecule of the learning process, Cotman nailed down a direct biological connection between movement and cognitive function.
Carl Cotman, director of the Institute for Brain Aging and Dementia at the University of California, Irvine,
He’d just finished working on a long-term aging study designed to see if the people whose minds hold up best share anything in common. Among those with the least cognitive decline over a four-year period, three factors turned up: education, self-efficacy, and exercise.
He set up an experiment to measure the levels of BDNF in the brains of mice that exercise. It was important that the exercise be voluntary because if he forced the mice to run on treadmills, he feared his peers might say the effect was from the stress of being handled. No problem: he’d use running wheels. As an indication of how new this territory was, finding rodent equipment that the university would approve for lab use was an ordeal in itself — Cotman had to pay $1,000 apiece for stainless steel running wheels that would pass protocol. “I remember signing the purchase order and thinking, This is painful; I just hope it doesn’t not work,” he jokes. On top of that, none of his postdoctoral students wanted anything to do with this research, and he had to go through a number of graduate students before finding a physical therapy major who liked the idea.
They were divided into four groups: mice running for two, four, or seven nights, and one control group with no running wheel. When their brains were injected with a molecule that binds to BDNF and scanned, not only did the scans of the running rodents show an increase in BDNF over controls, but the farther each mouse ran, the higher the levels were. When Cotman saw the results — that the spike occurred in the hippocampus — he didn’t believe them himself: “I said, No, c’mon guys, we did something wrong; the darn hippocampus is lit up. We had to repeat the experiment — it was too far out. And so we did, and we got the same results.”
“One of the prominent features of exercise, which is sometimes not appreciated in studies, is an improvement in the rate of learning, and I think that’s a really cool take-home message,” Cotman says. “Because it suggests that if you’re in good shape, you may be able to learn and function more efficiently.” Indeed, in a 2007 study of humans, German researchers found that people learn vocabulary words 20 percent faster following exercise than they did before exercise, and that the rate of learning correlated directly with levels of BDNF. Along with that, people with a gene variation that robs them of BDNF are more likely to have learning deficiencies. Without Miracle-Gro, the brain closes itself off to the world.
BDNF gives the synapses the tools they need to take in information, process it, associate it, remember it, and put it in context. Which isn’t to say that going for a run will turn you into a genius. “You can’t just inject BDNF and be smarter,” Cotman points out. “With learning, you have to respond to something in a different way. But the something has to be there.” And without question, what that something is matters.
it wasn’t until 1945 that a psychologist from McGill University named Donald Hebb stumbled onto the first hint of evidence. The lab rules were loose in those days, and apparently Hebb thought it would be fine if he brought some lab rats home as temporary pets for his children. The arrangement turned out to be mutually beneficial: When he returned the rats to the lab, Hebb noticed that compared to their cage-bound peers, they excelled in learning tests. The novel experience of being handled and toyed with somehow improved their learning ability, which Hebb interpreted to mean that it changed their brains. In his acclaimed textbook, The Organization of Behavior: A Neuropsychological Theory, he described the phenomenon as “use-dependent plasticity.” The theory was that the synapses rearrange themselves under the stimulation of learning.
this ties in with me randomly stimulating kittens, as they do to themselves as adolescents. solitary kitties soon become dull kittehs.
Living in an environment with more sensory and social stimuli, the lab tests showed, altered the structure and function of the brain. Not only did the rats fare better on learning tasks, but their brains weighed more compared to those housed alone in bare cages.
In examining cats raised with one eye sewn shut, they found that the visual cortex was significantly smaller. All this work established the metaphor of the brain as a muscle, and the notion of use it or lose it.
aha. just what i said a moment ago!
The Berkeley studies led to the creation of Head Start, the federal education program that provides funding to send disadvantaged children to preschool. Why should poor kids be left in bare cages? The field took off, and neuroscientists began to investigate different ways to stimulate brain growth.
that environmental enrichment made the neurons sprout new dendrites. The branching caused by the environmental stimulation of learning, exercise, and social contact caused the synapses to form more connections, and those connections had thicker myelin sheaths, which allowed them to fire signals more efficiently. Now we know that such growth requires BDNF. This remodeling of the synapses has a huge impact on the circuits’ capacity to process information, which is profoundly good news. What it means is that you have the power to change your brain. All you have to do is lace up your running shoes.
Certainly, we can speed up the decline, a point that your eighth-grade biology teacher may have made to scare you away from underage drinking. “Now, remember: alcohol kills brain cells, and they never grow back.” But guess what? They do grow back — by the thousands. Not until scientists became handy with advanced imaging tools that enabled them to peer into the brain did they find conclusive evidence, which was published in a seminal 1998 paper. It came from an unlikely source. Cancer patients are sometimes injected with a dye that shows up in proliferating cells so that the spread of the disease can be tracked. Researchers looked at the brains of terminally ill patients who had donated their bodies to science and found that their hippocampi were packed with the dye marker, proof that neurons were dividing and propagating — a process called neurogenesis — just like cells in the rest of the body. With that, they formalized one of the biggest discoveries in neuroscience.
One of the early clues about neurogenesis had come from studies of chickadees, which learn new songs every spring and also show a significant burst of new cells in the hippocampus.
in order for a cell to survive and integrate, it has to fire its axon.” Exercise spawns neurons, and the stimulation of environmental enrichment helps those cells survive.
Although all this research is in rodents, you can see how it might relate back to the kids in Naperville: Gym class provides the brain with the right tools to learn, and the stimulation in the kids’ classes encourages those newly developing cells to plug into the network, where they become valuable members of the signaling community. The neurons are given a mission. And it seems that cells spawned during exercise are better equipped to spark LTP. They are plastic phenoms, which led Princeton neuroscientist Elizabeth Gould to suggest that perhaps our new neurons play a role in hanging onto our conscious thoughts, while the prefrontal cortex decides if they should be wired in as long-term memories. Gould is the researcher who first showed that primates grow new neurons, paving the way for experiments on human neurogenesis.
What I find interesting, though, is that relatively few scientists are studying exercise because they’re interested in exercise. Rather, they make the mice run because it “massively increases neurogenesis,” as the title of a 2006 study in Hippocampus proclaimed, and thus allows researchers to deconstruct the chain of signals behind the process. That’s what the pharmaceutical companies need to create drugs. They dream of an anti-Alzheimer’s pill that regenerates neurons to keep memory intact. “There has to be some kind of chemical stuff in the [hippocampus] that is sensing exercise and saying, OK, let’s start cranking out new cells,” says Columbia University neurologist Scott Small, who recently used a novel MRI technique to track neurogenesis in live human subjects. “If we can identify those molecular pathways, we might be able to think of clever ways to induce neurogenesis biochemically.” Just imagine if they could put exercise in a bottle.
If we’re going to have new cells, we’ll need fertilizer for them, and from the get-go, neurogenesis researchers have been onto BDNF. They already knew that without Miracle Gro our brains can’t take in new information, and now they’ve seen that BDNF is also a necessary ingredient for making new cells. BDNF gathers in reserve pools near the synapses and is unleashed when we get our blood pumping. In the process, a number of hormones from the body are called into action to help, which brings us to a new list of initialisms: IGF-1 (insulin-like growth factor), VEGF (vascular endothelial growth factor), and FGF-2 (fibroblast growth factor). During exercise, these factors push through the blood-brain barrier, a web of capillaries with tightly packed cells that screen out bulky intruders such as bacteria. Scientists have just recently learned that once inside the brain, these factors work with BDNF to crank up the molecular machinery of learning. They are also produced within the brain and promote stem-cell division, especially during exercise. The broader importance is that these factors trace a direct link from the body to the brain.
Take IGF-1, a hormone released by the muscles when they sense the need for more fuel during activity. Glucose is the major energy source for the muscles and the sole energy source for the brain, and IGF-1 works with insulin to deliver it to your cells. What’s interesting is that the role of IGF-1 in the brain isn’t related to fuel management, but to learning — presumably so we can remember where to locate food in the environment. During exercise, BDNF helps the brain increase the uptake of IGF-1, and it activates neurons to produce the signaling neurotransmitters, serotonin and glutamate. It then spurs the production of more BDNF receptors, beefing up connections to solidify memories. In particular, BDNF seems to be important for long-term memories.
Which makes perfect sense in light of evolution. If we strip everything else away, the reason we need an ability to learn is to help us find and obtain and store food. We need fuel to learn, and we need learning to find a source of fuel — and all these messengers from the body keep this process going and keep us adapting and surviving.
To pipe fuel to new cells, we need new blood vessels. When our body’s cells run short of oxygen, as they can when our muscles contract during exercise, VEGF gets to work building more capillaries in the body and the brain. Researchers suspect that one way VEGF is vital to neurogenesis is its role in changing the permeability of the blood-brain barrier, prying back the fence to let other factors through during exercise.
Another important element from the body that makes its way to the brain is FGF-2, which, like IGF-1 and VEGF, is increased during exercise and is necessary for neurogenesis. In the body, FGF-2 helps tissue grow, and in the brain it’s important to the process of LTP. As we age, production of all three of these factors and BDNF naturally tails off, bringing down neurogenesis with it. Even before we get old, however, a drop in these factors and in neurogenesis can show up in stress and depression, as we’ll see later. To me, this is actually encouraging news, because if moving the body increases BDNF, IGF-1, VEGF, and FGF-2, it means we have some control over the situation. It’s about growth versus decay, activity versus inactivity. The body was designed to be pushed, and in pushing our bodies we push our brains too. Learning and memory evolved in concert with the motor functions that allowed our ancestors to track down food, so as far as our brains are concerned, if we’re not moving, there’s no real need to learn anything.
Now you know how exercise improves learning on three levels: first, it optimizes your mind-set to improve alertness, attention, and motivation; second, it prepares and encourages nerve cells to bind to one another, which is the cellular basis for logging in new information; and third, it spurs the development of new nerve cells from stem cells in the hippocampus.
One thing scientists know for sure is that you can’t learn difficult material while you’re exercising at high intensity because blood is shunted away from the prefrontal cortex, and this hampers your executive function. For example, while working out on the treadmill or the stationary bike for twenty minutes at a high intensity of 70 to 80 percent of their maximum heart rate, college students perform poorly on tests of complex learning. (So don’t study for the Law School Admission Test with the elliptical machine on full-tilt.) However, blood flow shifts back almost immediately after you finish exercising, and this is the perfect time to focus on a project that demands sharp thinking and complex analysis. A notable experiment in 2007 showed that cognitive flexibility improves after just one thirty-five-minute treadmill session at either 60 percent or 70 percent of maximum heart rate. The forty adults in the study (age fifty to sixty-four) were asked to rattle off alternative uses for common objects, like a newspaper — it’s meant for reading, but it can be used to wrap fish, line a birdcage, pack dishes, and so forth. Half of them watched a movie and the other half exercised, and they were tested before the session, immediately after, and again twenty minutes later. The movie watchers showed no change, but the runners improved their processing speed and cognitive flexibility after just one workout.
Cognitive flexibility is an important executive function that reflects our ability to shift thinking and to produce a steady flow of creative thoughts and answers as opposed to a regurgitation of the usual responses. The trait correlates with high-performance levels in intellectually demanding jobs. So if you have an important afternoon brainstorming session scheduled, going for a short, intense run during lunchtime is a smart idea.
the hippocampus isn’t off by itself somewhere, stamping out new circuits on its own accord. The learning process calls on a lot of areas, under the direction of the prefrontal cortex. The brain has to be aware of the incoming stimulus, hold it in working memory, give it emotional weight, associate it with past experience, and relate all this back to the hippocampus. The prefrontal cortex analyzes the information, sequences it, and ties everything together. It works with the cerebellum and the basal ganglia, which keep these functions on track by maintaining rhythm for the back-and-forth of information. Improving plasticity in the hippocampus strengthens a crucial link in the chain, but learning creates bushier, healthier, better connected neurons throughout the brain. The more we build these networks and enrich our stores of memory and experience, the easier it is to learn, because what we already know serves as a foundation for forming increasingly complex thoughts.
As for how much aerobic exercise you need to stay sharp, one small but scientifically sound study from Japan found that jogging thirty minutes just two or three times a week for twelve weeks improved executive function. But it’s important to mix in some form of activity that demands coordination beyond putting one foot in front of the other. Greenough worked on an experiment several years ago in which running rats were compared to others that were taught complex motor skills, such as walking across balance beams, unstable objects, and elastic rope ladders. After two weeks of training, the acrobatic rats had a 35 percent increase of BDNF in the cerebellum, whereas the running rats had none in that area. This extends what we know from the neurogenesis research: that aerobic exercise and complex activity have different beneficial effects on the brain. The good news is they’re complementary.
do a ten-minute aerobic warm-up before something nonaerobic and skill-based, such as rock climbing or balance drills. While aerobic exercise elevates neurotransmitters, creates new blood vessels that pipe in growth factors, and spawns new cells, complex activities put all that material to use by strengthening and expanding networks. The more complex the movements, the more complex the synaptic connections.
And even though these circuits are created through movement, they can be recruited by other areas and used for thinking. This is why learning how to play the piano makes it easier for kids to learn math. The prefrontal cortex will co-opt the mental power of the physical skills and apply it to other situations.
Studies of dancers, for example, show that moving to an irregular rhythm versus a regular one improves brain plasticity. Because the skills involved in these activities are unnatural forms of movement, they serve as activity-dependent learning of the sort that made Hebb’s rats smarter and that Greenough showed made synapses bushier.
Any motor skill more complicated than walking has to be learned, and thus it challenges the brain.
At first you’re awkward and flail a little bit, but then as the circuits linking the cerebellum, basal ganglia, and prefrontal cortex get humming, your movements become more precise. With the repetition, you’re also creating thicker myelin around the nerve fibers, which improves the quality and the speed of the signals and, in turn, the circuit’s efficiency. To take the example of karate, as you perfect certain forms, you can incorporate them into more complicated movements, and before long you have new responses to new situations. The same would hold true for learning tango. The fact that you have to react to another person puts further demands on your attention, judgment, and precision of movement, exponentially increasing the complexity of the situation. Add in the fun and social aspect, and you’re activating the brain and the muscles all the way down through the system. And then you’re primed and ready to move on to the next challenge, which is what it’s all about.
we’re talking about chronic stress, which translates emotional strain into physical strain. This is where the ripple effects of the body’s stress response can lead to full-blown mental disorders such as anxiety and depression, as well as high blood pressure, heart problems, and cancer. Chronic stress can even tear at the architecture of the brain.
ie, working as a pharmacist these days...
The way you choose to cope with stress can change not only how you feel, but also how it transforms the brain. If you react passively or if there is simply no way out, stress can become damaging. Like most psychiatric issues, chronic stress results from the brain getting locked into the same pattern, typically one marked by pessimism, fear, and retreat. Active coping moves you out of this territory. Instincts aside, you do have some control over how stress affects you.
Exercise controls the emotional and physical feelings of stress, and it also works at the cellular level. But how can that be, if exercise itself is a form of stress? The brain activity caused by exercise generates molecular by-products that can damage cells, but under normal circumstances, repair mechanisms leave cells hardier for future challenges. Neurons get broken down and built up just like muscles — stressing them makes them more resilient. This is how exercise forces the body and mind to adapt. Stress and recovery. It’s a fundamental paradigm of biology that has powerful and sometimes surprising results.
In the 1980s, the U.S. Department of Energy (DOE) commissioned a study on the health impacts of sustained radiation exposure. They compared two groups of nuclear shipyard workers from Baltimore who had similar jobs except for a single key difference: one group was exposed to very low levels of radiation from the materials they handled, and the other was not. The DOE tracked the workers between 1980 and 1988, and what they found shocked everyone involved. Radiation made them healthier. The twenty-eight thousand workers exposed to radiation had a 24 percent lower mortality rate than their thirty-two thousand counterparts who were not exposed to radiation. Somehow, the toxins that everyone assumed and feared were ruining the workers’ health were doing just the opposite. Radiation is a stress in that it damages cells, and at high levels it kills them and can lead to the development of diseases such as cancer. In this case, the radiation dose was apparently low enough that instead of killing the cells of the exposed workers, it made them stronger. Maybe stress isn’t so bad after all. But because the study “failed” — it didn’t show the expected malignant effect of radiation — it was never published. From what we’ve since learned about the biology of stress and recovery, stress seems to have an effect on the brain similar to that of vaccines on the immune system. In limited doses, it causes brain cells to overcompensate and thus gird themselves against future demands. Neuroscientists call this phenomenon stress inoculation.
Assuming that the stress is not too severe and that the neurons are given time to recover, the connections become stronger and our mental machinery works better. Stress is not a matter of good and bad — it’s a matter of necessity.
any degree of stress activates fundamental brain systems — those that manage attention, energy, and memory. If we strip away everything else, our ingrained reaction to stress is about focusing on the danger, fueling the reaction, and logging in the experience for future reference, which I think of as wisdom. It is only in recent years that scientists have begun to recognize and describe the role of stress in the formation and recall of memories.
The fight-or-flight response calls into action several of the body’s most powerful hormones and scores of neurochemicals in the brain. The brain’s panic button, called the amygdala, sets off the chain reaction on receiving sensory input about a possible threat to the body’s natural equilibrium. Being hunted would certainly qualify, but so would being the hunter. The amygdala’s job is to assign intensity to the incoming information, which may or may not be obviously survival related. It’s not just about fear, but any intense emotional state, including, for example, euphoria or sexual arousal. Winning the lottery or dining with a supermodel can trigger the amygdala. These events may not seem stressful, but remember, our brains don’t distinguish between “good” and “bad” demands on the system. And in an evolutionary light, good fortune and a good date are related to survival — prospering and procreating.
Humans are unique among animals in that the danger doesn’t have to be clear and present to elicit a response — we can anticipate it; we can remember it; we can conceptualize it. And this capacity complicates our lives dramatically. “The mind is so powerful that we can set off the [stress] response just by imagining ourselves in a threatening situation,” writes Rockefeller University neuroscientist Bruce McEwen in his book The End of Stress as We Know It. In other words, we can think ourselves into a frenzy.
We can literally run ourselves out of that frenzy. Just as the mind can affect the body, the body can affect the mind. But the idea that we can alter our mental state by physically moving still has yet to be accepted by most physicians, let alone the broader public.
If you’ve ever faced a nerve-racking public-speaking situation, you’ve experienced this shift in the form of a racing heart and cotton mouth. Your muscles and your brain get stiff, and you lose all hope of being flexible and engaging. Or, if the processed signal from the cortex to the amygdala breaks up, you can’t think and you freeze. Technically, the full-blown stress response should be called “freeze or fight or flight.” None of this is particularly helpful when you’re up at the podium, but the body responds in essentially the same way whether you’re staring down a hungry lion or a restless audience.
Two neurotransmitters put the brain on alert: norepinephrine arouses attention, then dopamine sharpens and focuses it. An imbalance of these neurotransmitters is why some people with attention-deficit/hyperactivity disorder (ADHD) come across as stress junkies. They have to get stressed to focus. It’s one of the primary factors in procrastination. People learn to wait until the Sword of Damocles is ready to fall — it’s only then, when stress unleashes norepinephrine and dopamine, that they can sit down and do the work. A need for stress also explains why ADHD patients sometimes seem to shoot themselves in the foot.
FUEL To fuel the anticipated activity of the muscles and the brain, epinephrine immediately begins converting glycogen and fatty acids into glucose. Traveling through the bloodstream, cortisol works more slowly than epinephrine, but its effects are incredibly widespread. Cortisol wears a number of different hats during the stress response, one of which is that of traffic cop for metabolism. Cortisol takes over for epinephrine and signals the liver to make more glucose available in the bloodstream, while at the same time blocking insulin receptors at nonessential tissues and organs and shutting down certain intersections so the fuel flows only to areas important to fight-or-flight. The strategy is to make the body insulin-resistant so the brain has enough glucose. Cortisol also begins restocking the shelves, so to speak, replenishing energy stores depleted by the action of epinephrine. It converts protein into glycogen and begins the process of storing fat. If this process continues unabated, as in chronic stress, the action of cortisol amasses a surplus fuel supply around the abdomen in the form of belly fat. (Unrelenting cortisol also explains why some marathon runners carry a slight paunch despite all their training — their bodies never get a chance to adequately recover.) The problem with our inherited stress response is that it mobilizes energy stores that don’t get used.
During the initial phase of the stress response, cortisol also spurs the release of insulin-like growth factor (IGF-1), which is a crucial link in fueling the cells. The brain is a conspicuous consumer of glucose, using 20 percent of the available fuel even though it accounts for only about 3 percent of our body weight. But it has no capacity to store fuel, so cortisol’s role in providing a steady flow of glucose is critical to proper brain function.
It’s simply not possible to have all of our neurons firing at once, so if one structure is active, it must come at the expense of another. One of the problems with chronic stress is that if the HPA axis is guzzling all the fuel to keep the system on alert, the thinking parts of the brain are being robbed of energy.
“All we can say is that if you don’t have adequate cortisol receptors in the hippocampus at the time these memories are being formed, the learning process is less efficient.
like stress itself, cortisol isn’t simply good or bad. A little bit helps wire in memories; too much suppresses them; and an overload can actually erode the connections between neurons and destroy memories.
The hippocampus provides context for the memory — the what, how, where, and when — and the amygdala provides the emotional content — the fear or the excitement. With direction from the prefrontal cortex, the hippocampus can compare memories and say, “Don’t worry; it’s a stick, not a snake,” and so has the capacity to shut off the HPA axis directly and put an end to the stress response. As long as it’s not overexcited. Within minutes of the alarm bell, cortisol, CRF, and norepinephrine — the major stress agents in the brain — bind to cell receptors that boost glutamate, the excitatory neurotransmitter responsible for all of the signaling in the hippocampus. Increasing glutamate activity speeds up the flow of information in the hippocampus and changes the dynamic at the synapses, so that each time a message is sent, the signal fires more easily, thus requiring less glutamate. Initially, then, the stress response enhances long-term potentiation (LTP), the fundamental mechanism of memory. Short-term memory probably results from this initial increase in the excitability of hippocampal neurons. Then, as levels of cortisol peak, cortisol turns on genes inside the cells that make more proteins used as building material for cells: more dendrites, more receptors, and bulkier synapses. This is where things get curious. The beefed-up cells cement the survival memory and shield the neurons in that circuit from other demands. A neuron might be part of any number of memories. But if a potential memory comes along during stress, it has a more difficult time recruiting neurons to be part of its own new circuit. It needs to clear a certain threshold to make an impression. This likely explains why memories not related to the stressor are blocked during the stress response. It also helps explain why constantly high levels of cortisol — due to chronic stress — make it hard to learn new material, and why people who are depressed have trouble learning. It’s not just lack of motivation, it’s because the hippocampal neurons have bolstered their glutamate machinery and shut out less important stimuli. They’re obsessed with the stress.
Human studies also show that excess cortisol can block access to existing memories, which explains how people can forget where the fire exit is when there’s actually a fire — the lines are down, so to speak. With too much stress, we lose the ability to form unrelated memories, and we might not be able to retrieve the ones we have.
With an overload of stress, as I’ll explain later, you get the petri dish effect — cortisol eroding neurons.
The human body is built for regular physical activity, but how much? In a 2002 article in the Journal of Applied Physiology, researchers studied this very question, by looking at our ancestors’ pattern of physical activity, which they call the Paleolithic rhythm.
From the time Homo sapiens emerged two million years ago, until the agricultural revolution, ten thousand years ago, everyone was a hunter-gatherer, and life was marked by periods of intense physical activity followed by days of rest. It was feast or famine. By calculating how much our forebears “exercised” and comparing it to figures from today, it’s easy to see where the problem lies: Our average energy expenditure per unit of body mass is less than 38 percent of that of our Stone Age ancestors. And I think it’s fair to say that our calorie intake has increased quite a bit. The kicker is that even if we followed the most demanding governmental recommendations for exercise and logged thirty minutes of physical activity a day, we’d still be at less than half the energy expenditure for which our genes are encoded. Paleolithic man had to walk five to ten miles on an average day, just to be able to eat.
This situation has come about only in the past century or so, but it takes tens of thousands of years for our biology to evolve — there’s a mismatch between our lifestyle and our genes. Human genes are thrifty by nature, so we end up stockpiling calories while we’re sitting at our desks.
And in modern life, people tend to have fewer friends and less support, because there’s no tribe. Being alone is not good for the brain.
It’s stressful to be shunned or isolated. Loneliness is a threat to survival. Not coincidentally, the less physically active we are, the less likely we’ll be to reach out and touch someone. Studies show that by adding physical activity to our lives, we become more socially active — it boosts our confidence and provides an opportunity to meet people. The vigor and motivation that exercise brings helps us establish and maintain social connections.
If you exercise or even just socialize, you’re tapping into the evolutionary antidote to stress.
It’s well known that the way to build muscles is to break them down and let them rest. The same paradigm applies to nerve cells, which have built-in repair and recovery mechanisms activated by mild stress. The great thing about exercise is that it fires up the recovery process in our muscles and our neurons. It leaves our bodies and minds stronger and more resilient, better able to handle future challenges, to think on our feet and adapt more easily.
In the brain, the mild stress of exercise fortifies the infrastructure of our nerve cells by activating genes to produce certain proteins that protect the cells against damage and disease. So it also raises our neurons’ stress threshold.
The cellular stress-and-recovery dynamic takes place on three fronts: oxidation, metabolism, and excitation.
When a nerve cell is called into action, its metabolic machinery switches on like the pilot light in a furnace. As glucose is absorbed into the cell, mitochondria turn it into adenosine triphosphate (ATP) — the main type of fuel a cell can burn — and just as with any energy conversion process, waste by-products are produced. This is oxidative stress. Under normal circumstances, the cell also produces enzymes whose job it is to mop up waste such as free radicals, molecules with a rogue electron that rupture the cell structure while careening around trying to neutralize the electron. These protective enzymes are our internal antioxidants. Metabolic stress happens when the cells can’t produce adequate ATP, either because glucose can’t get into the cell or because there’s not enough of it to go around.
Excitotoxic stress occurs when there is so much glutamate activity that there isn’t enough ATP to keep up with the energy demand of the increased information flow. If this continues for too long without recovery, there’s a problem. The cell is on a death march — forced to work without food or resources to repair the damage. The dendrites begin to shrink back and eventually cause the cell to die. This is neurodegeneration, the mechanism underlying diseases such as Alzheimer’s, Parkinson’s, and even aging its <You have reached the clipping limit for this item>