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.
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.
Ruben Baler, Ph.D., is not your typical neuroscientist. Baler has studied in his native country Argentina, the U.S., and Israel. He is fluent in three languages. His work at NIDA enables him to publish scientific papers and collaborate on presentations and speeches with NIDA’s Director, Nora D. Volkow, M.D. His true passion is teaching young people about the brain. He talks to college students at George Washington University in Washington, DC, and regularly interacts with high school students in and around the Washington, DC, area. Dr. Baler talks in this podcast about the teen brain—how it develops fast, just like teens themselves. And how, sometimes, that growth keeps young people from using their best judgment when it comes to risky behaviors, such as experimenting with drugs and alcohol, driving too fast, or jumping headlong into relationships.
Dr. Baler: Hello, my name is Ruben Baler. I am [a scientist] with the National Institute on Drug Abuse, NIDA. It’s probably helpful to think of the brain as a computer, which in essence, it is. It’s a very complex computer. It’s made up of circuits that affect or mediate all sorts of different functions in the brain. You can think of the learning circuit, the memory circuit, the higher thinking (cognitive function) circuit. There are all sorts of networks in the brain that interact with each other and with the environment. They are the substrates (or key brain areas) where drugs of abuse have their effects. The main substrate in the brain that is impacted by drugs of abuse is called the circuit of reward. It is the area deep inside the brain that influences feelings of reward, feelings of pleasure. Drugs of abuse hijack the normal pathways of reward and lead the brain to think that the drug-induced experience is the highest possible goal from now on.
SBB: What makes the teenage brain so special?
Dr. Baler: One of the main reasons is that different parts of the brain develop at different rates. There are two main parts: one area, called the amygdala, governs our instincts, our gut feelings. That area develops early on and is already mature in a teenager. Then there is another area called the prefrontal cortex, a part of the brain that takes much longer to develop, to fully mature. The teen brain is different because the ability to make good decisions really depends on the balance between these two structures: the prefrontal cortex and the amygdala, part of the limbic system that develops so early on.
So we can say that teenagers make decisions mostly based on this instinctual part of the brain, these gut feelings, because the prefrontal cortex has not yet reached [developed] the ability to fully exert control and keep tabs on the already-mature limbic system.
SBB: Do you think that by studying the brain and knowing how it’s linked to addiction and other high-risk behaviors, teens can learn to “tame” their brains?
Dr. Baler: Well, one school of thought says that by providing fact-based information to teenagers—like the fact that their brains are still developing and they may make decisions differently than adults—may urge them to stop and think, and make better decisions as a result.
There are big, big questions in neuroscience. For example: where is consciousness? Where does consciousness lie? We’d like to understand how this computer (the brain) leads to things like music, creativity, poetry—very complex products of this very complex machine.
*Note: In order to hear the podcast you will need to have a media player on your computer.
You may think you know what addiction is—lots of people have many different opinions about addiction and different ways of defining it. Here are some myths you may have heard:
- Getting over addiction to drugs is a choice.
- In order for treatment to work, the person has to hit “rock bottom.”
- People have to choose to get treatment or it won’t be effective, such as when a judge sends a person to treatment facility instead of jail.
The truth is that addiction is a complex brain disease that scientists are still figuring out. For instance, one person may use a drug once or many times and nothing bad happens, while others may overdose with the first use. Some people use drugs regularly and never become addicted, while others try drugs once or twice and do become addicted. There is no way of knowing in advance how a person may react to these dangerous substances. Whether or how quickly addiction takes hold in individuals depends on many factors, including:
- Genes: Research shows that some people’s genes may leave them more susceptible to addiction than other people’s.
- Environment: Kids who are exposed to drug use in their families or neighborhoods are at greater risk of engaging in drug abuse themselves.
- Age at first use: The younger a person uses drugs, the more vulnerable he or she is to addiction in adulthood. Since the brain continues to develop well into a person’s twenties, using drugs in the teen years can set a person up for later drug problems.
What scientists know for sure is that many drugs “turn on” the brain’s reward circuit, which is part of the limbic system. The person then learns to associate the drug with pleasure and starts to crave it more and more, leading to compulsive drug use and often to addiction. In an addicted person, the brain changes in ways that cause compulsive drug seeking and use, despite negative consequences, so even if they want to quit, they can’t without treatment and support. That’s why addiction is considered a brain disease. Other activities in life also activate the brain’s reward circuit and can cause “driven” behaviors, such as compulsive overeating or video game playing. However, scientists are still trying to figure out why this happens in non-drug contexts—it may be connected to dopamine levels in the brain. Learn more about the science behind drug addiction by visiting http://nida.nih.gov/scienceofaddiction/.