NIDA’s Glossary defines the limbic system as “a set of brain structures that generates our feelings, emotions, and motivations. It is also important in learning and memory.”
The limbic system, known informally as the “center for emotions,” is made up of five parts that help ensure our survival, including the ability to feel emotion, long-term memory storage, memory retrieval, and other behaviors directly connected with the emotions.
Each part has a separate role that makes the system run smoothly.
1) Amygdala—a tiny, almond-shaped structure commonly associated with processing emotions like anger, fear, and pleasure.
2) Cingulate Gyrus—a structure that receives messages from other parts of the brain and is essential in higher thinking functions, respiratory control, and memory, and learning.
3) Fornix—a tough, arch-shaped band that connects the two lobes of the cerebrum (the large rounded structure that makes up most of the brain and is divided into two hemispheres).
4) Hippocampus—a brain structure that is key to memory storage and retrieval; damage to it often means significant long-term memory loss.
5) Hypothalamus—a brain structure that regulates involuntary or automatic responses, including body temperature and food digestion. Drugs disrupt the feelings and motivations that form the basis of normal behavior. A person abusing drugs is artificially feeling pleasure by interfering with the limbic system.
According to NIDA’s glossary, polyneuropathy is a “permanent change or malfunction of nerves.” “Poly” means “many,” so multiple nerves throughout the body such as in the arms, legs, hands, and feet are affected.
Possible symptoms of polyneuropathy are weakness, the feeling of pins and needles, or burning pain. In the most extreme cases, people can have trouble breathing and experience organ failure.
Many things can cause polyneuropathy, from genetics to a nutritional deficiency. But something else can also cause it—inhaling toxic, poisonous fumes, like those found in certain household products, in order to get high.
Long-term inhalant abuse can break down myelin, a fatty tissue that surrounds and protects some nerve fibers. Myelin helps nerve fibers carry their messages quickly and efficiently throughout the body and to the brain. Damaged myelin can lead to muscle spasms and tremors or even permanent difficulty with basic actions like walking, bending, and talking.
Don’t forget about sudden sniffing death, which can occur when inhaled fumes fill up the cells in the lungs with poisonous chemicals, leaving no room for the oxygen needed to breathe. This lack of oxygen can lead to nerve damage, suffocation, and even death.
Sudden sniffing death could occur during a person’s 100th time using inhalants or the first time. There’s no way to predict it.
Learn more about the consequences of abusing inhalants.
Regardless of whether or not teens should care about body image or physical appearances, the truth is that we do care, a lot. And working out is a healthy way to look and feel better. The trouble comes when people sacrifice their health to look buff—like by taking steroids.
While not that many teens try steroids even once, according to NIDA surveys (about 3 in 100), those who do use steroids are getting a lot more than just larger muscles. Steroids can cause acne and make your hair fall out. They can also damage your heart and change your hormone levels so that girls might grow facial hair, and boys could develop breasts. Seriously. NIDA scientist Dr. Baler reveals more about what steroids can do in the video to the right.
According to a recent driving study, as many as 1 in 5 teen drivers say they drove under the influence of marijuana. More than one-third of them did not believe that marijuana affected their driving, whereas less than one-fifth of teens who drove after drinking alcohol said their driving wasn’t impaired.
These numbers show that some teen drivers aren’t getting the message that both alcohol and drugs—including marijuana—are dangerous risks behind the wheel. Not only that, but drivers under the influence of these substances endanger other users of the road as well.
Reducing drunk driving has been a focus of public health campaigns in the United States for a long time. After all, SADD, which now stands for Students Against Destructive Decisions, started out as Students Against Drunk Driving. Only recently have people started talking about how driving high or buzzed is just as risky as driving drunk.
Your Brain in the Driver’s Seat
Because driving is such a common activity, it’s easy to forget how you really must stay alert to stay safe. While it may seem like your body goes on automatic when accelerating or changing lanes, really your brain is in high gear.
Drugs and alcohol interfere with the brain’s ability to function properly. THC, the main active ingredient in marijuana, affects areas of the brain that control the body’s movements, balance, coordination, memory, and judgment, so it’s no surprise that marijuana and driving don’t mix.
Speak Up
The driving study mentioned above also found that 90% of teen drivers would stop driving under the influence of marijuana if asked by their passengers. If you see someone who’s about to drive after using marijuana, tell them it’s not a good idea.
Note: Drugs and alcohol aren’t the only things that may mess with your driving skills—check out Distraction.gov to find out about how eating, using a GPS, texting, or talking to passengers can also lead to an accident.
Our bodies can do lots of things without us even thinking about it. And that’s what the Word of the Day is about. The brainstem, not surprisingly, is a “stem” that connects the brain to the spinal cord. Its basic functions include directing heart rate, breathing, arousal, and sleeping. Lucky for us, the brainstem does all these things automatically. That’s why you don’t forget to breathe when you’re asleep!
How? The brainstem directs the spinal cord, other parts of the brain, and the body to do what is necessary to maintain our life.
The brainstem is one of the more primitive parts of our brain—it dates back to the age of the dinosaurs! Just like another primitive part of our brain, the limbic system.
One of the reasons that addictive drugs exert such powerful control over our behavior is that they act directly on our primitive brainstem and limbic system.
For more brainy words, check out the NIDA for Teens glossary that fuels SBB’s words of the day.
Hi, my name is Eric Wargo and I’m a new science writer here at NIDA. Before coming to NIDA, I wrote for an association of psychological scientists, people who study all aspects of the mind and human behavior. I was excited to come to NIDA, because NIDA scientists study the brain, and the brain is at the root of everything we humans do.
The brain is almost like magic: It has the ability to transform thoughts and feelings into real physical actions and physical states like health or illness. And something as simple as an idea or a belief can have a real effect on your well-being or how well you do in school or in your relationships. I’ve always been especially interested in ways people can improve themselves—and even achieve many of the things some people seek through drugs—through activities that change their brains. SBB asked me to write some guest columns on this topic. I hope you enjoy them!
Learning Changes the Brain
If you’ve been reading this blog, you know all about how drugs change the brain. But lots of things besides drugs change the brain, and lots of those brain changes are good.
Learning is the #1 positive thing that changes your brain. Something as small as a new experience or learning a new word rapidly creates or reinforces new connections between neurons, even hundreds or thousands of them, in real time. You aren’t exactly the same person now, after reading the last sentence, as you were before you read it—because your brain changed a little.
And guess what—just knowing that fact can actually make you smarter.
Challenge Your Mindset
A few years ago, I was blown away when I heard a really amazing lecture by a psychologist named Carol Dweck. She has studied how people’s “mindsets”—specifically the beliefs they hold about whether someone’s intelligence is changeable—have a strong effect on how well they succeed in school and in life. People who think that intelligence is just something you are born with (or not) don’t apply themselves as much when it comes to learning. Even if they are told they are smart, they may not try as hard and actually may not ultimately achieve as much or handle challenges as well as those who believe that smartness depends mainly on how much effort they put in.
Dweck tested this idea with junior high school students. It can be a tough period in life, as you may have found out yourself. A lot of kids who were happy and did well in elementary school suffer setbacks when they hit junior high—they become frustrated and unhappy and stressed, and where they were once good students, they suddenly see their grades go down. In one study, Dweck and a couple of her colleagues found that students who held the “intelligence is changeable” mindset were more motivated to learn and actually performed better in math over the course of 7th and 8th grades than did those who believed their intelligence was a permanent, fixed quantity.
So Dweck and her team designed an intervention to help students whose math grades were falling. Over the course of 8 weeks, a group of these students were taught about how the brain works, including the way learning actually builds new and stronger connections between neurons and how the brain is like a muscle that can be strengthened through the exercise of learning. A comparison group also learned about the brain and study skills but without the emphasis on the brain’s changeability.
You can probably guess what happened: The students who learned about how their brains change actually reversed their plummeting math grades—they started doing better! Those who were not exposed to this idea continued doing poorly in math. (Dweck has now taken her intervention, called “Brainology,” and developed it for use by schools and teachers.)
The bottom line: Mindsets are super-powerful in setting people either on a path to success or on a path to something less. People who (correctly) believe their brains change go farther, do more, and adapt better to life’s challenges. So help spread the word to your peers: Your brain changes and you can choose how you change it.
Next time, I’ll talk about some cool things you can do to change and hone your brain.
Eric Wargo writes about the brain and addiction for NIDA’s Office of Science Policy and Communications. He has a Ph.D. in anthropology, and in his spare time, he writes and blogs about science, history, movies, and other cool topics.
What do walnuts and our Word of the Day have in common?
Well, it’s a stretch, but fun to think about. If you crack open a walnut carefully, you can see it has two “sides”—just like the human brain. And that’s where our “word of the day” comes in.
The cerebral cortex covers most of the other brain parts inside your head—making up two-thirds of the brain’s mass. No surprise, since the cerebral cortex is what allows us to speak and understand, learn languages, play music, and a lot more.
Like a walnut, the cerebral cortex has two sides called “hemispheres.” The left hemisphere rules things like our ability to talk, write, and learn languages. The right hemisphere rules our musical abilities, and how we figure out distances and other “spatial” challenges. For example, does it look like you and all your friends can fit into that diner booth? Oops, not quite.
And that’s not all. Our sense of touch also uses both hemispheres of our brain! Walnuts anyone?
For more brainy words and others, check out NIDA’s glossary.
I’ve always been a huge Star Trek fan. When I was a teenager, my hero was Mister Spock—cool, analytical, even-tempered, and smarter than everyone around him. Being raised in his ancient society of the planet Vulcan made him a force to be reckoned with. He was kind and compassionate, but his mind was unswayed by human passions and fears, and he was always in control. When he was alone, he often sat, eyes closed, deep in meditation.
Vulcan is a fictional planet, but I later came to learn that there are real people on Earth kind of like Mister Spock, who possess many of his qualities and abilities because they have trained their brains in ancient Eastern mental arts.
Going to a “Zen Place”
A German philosophy professor named Eugen Herrigel discovered the power of a calm mind when he went to Tokyo in the 1920s. One day, he was having lunch with a Japanese colleague when an earthquake struck. Panic quickly broke out, and most of the diners (including Herrigel) jumped up and hurried out of the restaurant.
But the man Herrigel was having lunch with remained seated with his hands folded, his eyes nearly closed, completely undisturbed by the shaking going on around them. Fascinated by his companion’s trance-like calm, Herrigel sat down too and felt strangely safe. When the earthquake was over, the man continued the conversation exactly where it had broken off, saying nothing about what had just happened.
A few days later, Herrigel learned the source of his lunch partner’s amazing, infectious calm—he was a Zen Buddhist. His emotional steadiness came from practicing meditation.
Buddhist literature is full of stories of people achieving amazing feats of insight, courage, and even control over their own bodies after years of practicing simply sitting and focusing their minds. Such people often become rocks of support, giving strength to those around them, or even become calmly inspiring leaders themselves.
Meditation’s Effects on the Brain
Brain scientists have gotten really interested in the effects of meditation on the brain. A Harvard psychologist named Richard Davidson has done brain scans on dozens of Buddhist monks and found that their training has permanently altered their limbic systems, giving them heightened empathy—or the ability to understand and identify with another person’s feelings.
A recent study of “beginner” meditators by another Harvard researcher found that 8 weeks of training in techniques like mindfulness meditation and yoga increased gray matter in brain regions involved in memory, learning, emotion, breathing, and motor control.
[Caption: These high-resolution brain image scans show where gray matter increased in different parts of the brain for those who practiced mindfulness.. A: The posterior cingulate cortex and cerebellum; B: The left temporo-parietal junction; C The cerebellum and brainstem.]
The bottom line is, the brain is a powerful instrument, and you can make it do even more amazing things when you sharpen and enhance its powers. Wouldn’t it be cool to have a tough, disciplined, compassionate, and fearless brain like a Buddhist monk … or Mister Spock? P.S. After his remarkable experience with the Zen man in the earthquake, Eugen Herrigel promptly decided to learn Zen himself, and went on to study with a Zen master for 6 years. He then wrote a classic book about his experience, called Zen and the Art of Archery, as well as a short introduction to Zen philosophy and meditation (which I highly recommend, if you are interested) called The Method of Zen.
Eric Wargo writes about the brain and addiction for NIDA’s Office of Science Policy and Communications. He has a Ph.D. in anthropology, and in his spare time, he writes and blogs about science, history, movies, and other cool topics. Read his previous SBB guest post, Mindset Over Matter.
Imagine this: You're playing basketball; it's the last quarter. In fact, you only have 30 seconds to make the winning shot. You shoot, it soars through the air, you hear the buzzer go off...and then you see the swoosh.
You just won the game for your team. How do you feel?
The answer to that question involves a chemical in your brain, called dopamine—our word of the day. Dopamine delivers important messages between neurons (brain cells). That's why it's called a "neurotransmitter." Dopamine is an especially important neurotransmitter, because it helps to control movement, motivation, emotions, and sensations like pleasure.
Back to the basketball game. After you made that winning basket, dopamine sent "messages" to your neurons to help you feel happy, pumped, and overjoyed that you made that winning shot. Dopamine would also be working away in your teammates' brains as they ran out onto the court to celebrate, and in the brains of the cheering fans jumping up and down in the stands.
But it doesn't stop there. Dopamine is at work all the time, delivering messages to neurons and motivating you to participate in the more basic activities of life, like eating foods you like or spending time with family and friends. How dopamine works in the brain is especially important in teens since teens' brains are still developing. When dopamine levels are affected by drugs like cocaine, it can affect the brain's "wiring," causing important messages to get lost in translation. Messing with dopamine can affect your motivation to go to prom or ability to make that winning basketball shot,—even your ability to feel happiness. And that's why drugs might cost you more than just the basketball game.
For more in-depth resources and other brainy words, check out NIDA's interactive glossary that fuels my "Words of the Day."
Many teenagers assume smoking weed is harmless because of all the myths floating around saying it’s safe. What few people know is that the age you start using marijuana actually makes a difference. In fact, if you start smoking it as a teenager, there can be some serious problems for you down the road.
Although we already knew from past research that if you start smoking pot as a teen, you’ll be more likely to get addicted, new research (just published in a well-known journal called Proceedings of the National Academy of Sciences) now says if you smoke marijuana heavily as a teenager, it can actually lower your IQ!
Scientists looked at more than 1,000 people born in 1972 and 1973. When they were 13 years old, they were given IQ and other kinds of intelligence tests. They were interviewed every few years about their use of marijuana and then tested again when they were 38 years old.
The results? Those who smoked weed heavily as teens showed mental decline even after they quit using the drug—and had, on average, an 8-point drop in their IQ scores. An 8-point loss could push a person of average intelligence into the lower third of testers. Those who started smoking pot after age 18 also showed some decline, but not as much.
This was an interesting study because it also collected information from people who knew the study participants. They reported that people who smoked marijuana heavily had more memory and attention problems and did not organize their lives as well, misplacing things and forgetting to keep appointments, pay bills, or return calls. This highlights the lasting effect marijuana can have on the teenage brain, which is still developing and still wiring itself to handle the onslaught of information it gets every day. The toxic chemicals in marijuana can mess up that wiring process and hurt your ability to do well in school and in life.
Carol Krause is the Chief of the Public Information and Liaison Branch at NIDA. Since arriving at NIDA in 2006, Ms. Krause has launched several new innovative programs for teens, including Drug Facts Chat Day (an annual live Web chat between NIDA scientists and teens), National Drug Facts Week (to stimulate community events between scientists and teens), and the first Addiction Science Awards for high school participants in the Intel International Science and Engineering Fair.
Our word for today is: Cerebellum
Cerebellum: A portion of the brain that helps regulate posture, balance, and coordination during activities such as playing ball, picking up objects, and balancing.
Why do I like this word so much? Say it again: "cer·e·bel·lum" (s?r'?-b?l'?m)—yup, it's my namesake! When we walk down the street or concentrate on keeping our balance, our cerebellum is guiding us. The cerebellum coordinates our voluntary muscle movement as well as our posture and balance, like a puppeteer helping us put one leg in front of the other. Suppose you're playing ball? Picking up your pet? Playing a musical instrument? Your cerebellum is hard at work inside your head so you can slam dunk that basketball, hold onto the cat, and play each note on your electric guitar perfectly. And these are just a few of the activities that the cerebellum handles for us. The cerebellum is located just above the brainstem, where our brain connects to our spinal cord. The average teen's cerebellum weighs about 6 ounces. That's about one-eighth of the total weight of our brain, which weighs about 3 pounds. Hmm...who knew something so little could be so powerful? You can look up more words in the NIDA for Teens glossary.
The brain controls just about everything we do, think, and feel. It coordinates all of the body’s physical functions—like standing, walking, and breathing—as well as our memory, emotions, and behaviors.
Managing all of those jobs requires 100 billion neurons, or brain cells. And those neurons have trillions—yes, trillions—of connections through synapses, or routing switches that control how these nerve impulses travel around the brain and through the body.
With so much going on in that tightly packed space between our ears, it’s no wonder the brain requires its own field of scientific research—neuroscience.
“Brain science allows us to try and understand what makes us uniquely human and drives our behaviors and response to others,” says NIDA Director Dr. Nora Volkow.
NIDA Interviews Neuroscientists
To spotlight researchers whose work is advancing the science of the brain, NIDA interviewed several top neuroscientists investigating drug abuse and addiction. Four scientists in this group of video clips talk about what attracted them to study the brain—and all are obviously excited about how their research is increasing our knowledge about the brain and how drugs affect it.
Have you ever considered a career studying the brain?
- On addiction science: Nora D. Volkow, M.D., NIDA Director
- On brain plasticity: Anne West, Ph.D., Duke University Medical Center
- On memory and emotional learning: Elizabeth Phelps, Ph.D., New York University
- On the impact of stress in the brain: Anthony Grace, Ph.D., University of Pittsburgh
You may remember hearing something about neurons in biology, but what about today’s word of the day: axon?
Neurons are nerve cells in the brain that communicate with each other 24/7 to control everything we do, think, and feel. The axon is the long, tunnel-like part of the neuron (see picture) that steers messages from the cell to other nerve cells or body tissues, such as muscles.
Since the axon’s only job is to transmit messages from point A to point B, it can focus on doing it fast. For this reason, many axons are lined with a fatty material called myelin, which helps the message glide through the axon quickly. Prolonged drug use can damage the axon or the myelin, causing noticeable changes in a person’s behavior over time.
For example, scientists have discovered that abusing certain drugs on a long-term basis—like inhaling fumes or markers—can eat away at myelin. Without its protective myelin lining, the axon itself is more vulnerable to harm. An axon that is damaged or is missing myelin cannot transmit messages as well to other nerve cells, if at all. For someone with damaged axons, this can mean muscle spasms, tremors or difficulty with basic motor skills, like walking, bending, or talking.
More info is available on the NIDA for Teens’ Web site about axons and their role in the brain’s communication system, as well as inhalants and their effects on the body.
There’s no better time than the upcoming Brain Awareness Week, from March 11‒17, to learn more about the most fascinating organ in your body.
The included image from the Society for Neuroscience, a partner of the Dana Foundation for Brain Awareness Week, shows some of the most critical parts of your brain.
Here’s what each part is primarily responsible for—and guess what? As the image shows, these are also the brain regions most affected by drugs of abuse:
Prefrontal cortex: This part is often referred to as the “CEO of the brain.” The prefrontal cortex is responsible for critical thinking and abstract thought, as well as many other functions like focusing attention, organizing thoughts, controlling impulses, and forming strategies for future action. The prefrontal cortex is one of the last regions of the brain to mature, so changes caused by drug abuse could have long-lasting effects.
Nucleus accumbens: Part of the so-called “pleasure center,” the nucleus accumbens is thought to play an important role in reward, pleasure, laughter, aggression, and fear.
Amygdala: Research shows that the amygdala has a major role in processing memory and emotional reactions, such as fear. The amygdala is part of the limbic system.
Hippocampus: Also part of the limbic system, the hippocampus plays important roles in moving information from short-term memory to long-term memory.
Ventral tegmental area: This structure is important in thinking, motivation, and intense emotions relating to love.
Scientists are constantly studying the brain and learning more and more about how different brain structures relate to addiction. We know drugs change the brain, but the effects of these changes are not yet fully understood.
Protect your brain. Make the healthy choice to stay away from drugs and alcohol.
What questions do you have about the brain? Let us know in comments. And Happy Brain Awareness Week!
“This is drugs. This is your brain on drugs. Any questions?”
Sound familiar? For some of our readers, maybe not. This line actually dates back to the Partnership for a Drug-Free America’s 1987 classic television public service campaign. Perhaps even more memorable than the slogan was the imagery that accompanied it—a sizzling egg in a hot frying pan. Check out the video and see for yourself.
When it launched in the late 1980s, this classic public service campaign challenged the idea that drugs’ effects were temporary. The campaign message that drug addiction changes people’s brains and shatters people’s lives would soon start to take hold.
Brain Scans Replace Fried Eggs
Today, we don’t have to use a frying egg to demonstrate what a “brain on drugs” might look like. Through the use of brain-imaging technology, science can show us a real picture of how drug use affects the brain. By measuring the amount of glucose in a particular area of the brain, a brain scan (called positron emission tomography) can tell how active the brain is.
Take a look at the “control” scan on the left, which is the brain of a normal person. Look at all the red—this means that these regions of the brain are highly active since red represents glucose. The right scan is taken from someone who is on cocaine. What do you notice? A lot less red, right?, which means less activity. Reduced glucose can affect many brain functions, such as decision-making, memory, and concentration.
“This is your brain on drugs” just got a whole new meaning.
What drug-prevention slogans or images have the greatest impact on you? Send us a message or leave us a comment, and let us know what you think.
Is your brain an organic computer? Your brain does a lot of things a computer does, like math, logic, analyzing input, creating output, and storing and retrieving information. Even at the cellular level, there are some striking similarities between brains and computers. Our brain has billions of neurons that convey and analyze electrical information. This information is binary, meaning a neuron either fires a burst of electricity or it does not fire at all. Likewise, computers transmit information electrically. And at the most basic level, computers work using bits of information that are also binary, where each bit of information is either a “1” or a “0,” nothing in between.
But brains do a lot of things that computers cannot. Our brains feel emotions, worry about the future, enjoy music and a good joke, taste the flavor of an apple, are self-aware, and fall in and out of love. Albert Einstein’s famous equation E=MC2 was not the result of a computer algorithm but, rather, of a brain making a great intellectual leap. If a brain is merely an organic computer, how can it do these things?
Part of the answer may be that whereas neurons process information like a computer, they are not the only type of brain cells processing information. Neurons only make up a small portion of your brain cells—about 15 percent.
Enter the All-Important Glia Cells
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The vast majority of brain cells are called “glia” cells. For over 100 hundred years, most brain scientists saw glia as being relatively unimportant. Their function was believed to be mostly cleaning up “molecular trash” created by neurons. However, research is now showing that glia do much more than housecleaning. They are involved in learning and memory, and they help repair damaged brain areas. Glia can also communicate with neurons and with each other through “gap junctions” across large areas of the brain.
To illustrate how important glia are, almost every disease of the brain is partly or solely the result of glia malfunction. Scientists are now discovering that glia may also play a pivotal role in drug abuse, where changing glia activity may reduce drug abuse and addiction.
David Thomas is a NIDA scientist and Program Officer. He received a Ph.D. in Experimental Psychology from American University in Washington, DC, and has conducted research in analgesia (pain relief) and itch. He currently works at NIDA promoting research to find better pain medications that are not addictive
