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WHAT'S INSIDE THE TEENAGE BRAIN.
(how neurochemistry affects thought processes) Kathiann M. Kowalski. Current Health 2, Nov 2000 v27 i3 p6
Full Text: COPYRIGHT 2000 Weekly Reader Corp.
Research is constantly changing scientists' understanding of the human brain and its growth. The emotional ups and downs of your teen years may have a connection with how your brain develops.
Sara has math, history, and biology homework tonight, plus an English report due Monday. Dance class is at 8 p.m. Plus, Sara knows it's her night to wash dinner dishes. Nonetheless, she spends two hours on the phone after school.
"What do you mean you haven't started your homework yet?" her dad finally asks at 10 p.m. "Can't you get organized?"
With discipline and motivation, Sara can learn organization and study skills and put them into practice. But part of her organization difficulties may literally be inside her head.
Making Connections
Even simple tasks can involve complex interconnections among your 3-pound brain's billions of neurons, or nerve cells. As you begin to comprehend new material covered in class, for example, different groups of neurons cooperate with each other and fire in synchronized patterns.
The number of neuron connections increases tremendously throughout early childhood as the brain grows. Until recently, most scientists believed maximum brain growth occurred by age 6. After age 6, they believed, the number of neural connections decreased as the brain "weeded out" unused links.
Recent research, however, has changed this view. Now it appears that the brain forms new neuron connections well into its owner's teens, and possibly even into a person's 20s. Jay Giedd at the National Institute of Mental Health has compared the growth of teens' brains to trees sprouting new branches.
Many new connections form in and around the corpus callosum. This bundle of neurons "wires" the brain's two halves to each other and plays a significant role in self-awareness (for example, being able to understand and appreciate one's abilities).
Much of the development also occurs in areas of the brain's cerebrum, which is the largest part of the brain and is divided into two halves. These areas of the cerebrum are used in making judgments and controlling emotions. In part, Sara's disorganization may mean that she's still relying more on her brain's emotional centers than on areas that should eventually help her exercise good judgment. Likewise, when Dan decides that his teacher looks angry--when she's really worried about something--he may not yet have developed sufficient judgment to interpret her facial expressions accurately.
Risks vs. Opportunities
The teenage brain's developmental changes may contribute to the occasional emotional turmoil teens experience. The fact that judgment is still developing may also explain part of teens' tendencies to take risks. When new, exciting activities cause neurons to release neurotransmitters, such as dopamine, that make you feel good, risky behavior may produce emotional rewards, too.
Add in the stress of hormone changes, and things can get really frustrating. Testosterone surges during puberty make an almond-shaped part of the limbic system, called the amygdala, swell. The limbic system generates emotions such as fear and anger. The swelling of the amygdala can intensify feelings of aggression or fear.
Of course, you can't blame everything on the brain. Everyone is responsible for his or her own actions. And brain changes alone certainly don't explain all the emotional ups and downs of the teen years.
However, understanding your brain's changes can help you be more patient with yourself and with others. Realizing that your brain functions are still developing--and improving--may make it possible to rein in impulses that are based on purely emotional responses. One way to increase your chances of making good choices is to ask for advice and support from adults you can trust. That's what you call picking their brains!
There's good news, too. Continuing brain development means teens still have lots of opportunities to learn and change. So, if you've always wanted to play the guitar, dabble in art, or play chess, you have time to learn to shine.
Everyone should continue learning. When it comes to maintaining the brain's neuron connections, the rule is "use it or lose it." In other words, if connections between neurons aren't used, the brain eliminates them. A healthy appetite for learning can help you form and maintain neuron connections throughout life.
Chemical Messengers
When a neuron's dendrites get stimulated, it sends an electrical signal through the cell body and down a long axon. At the end of the axon, the neuron then releases chemicals, called neurotransmitters, to send signals to nearby neurons across tiny gaps, known as synapses.
Your brain relies on about 50 different neurotransmitters. Examples include:
Acetylcholine (ACTH)--affects brain activity related to attention, learning, and memory
Dopamine--stimulates feelings of pleasure and affects arousal levels
Endorphins and enkephalins--reduce stress and ease pain
Glutamate--plays a vital role in learning and long-term memory
Noradrenaline--stimulates mental and physical arousal and heightens mood
Serotonin--affects mood levels, sleep, appetite, and other functions.
After a neurotransmitter stimulates a nearby neuron by attaching to receptors on its dendrites, the presynaptic neuron's terminal absorbs it through a process called reuptake. Reuptake keeps neurons from constantly being fired.
Knowledge about neurotransmitters can help doctors treat various diseases and disorders. The antidepressant drug Prozac, for example, helps treat depression by slowing reuptake of serotonin.
On the other hand, substance abuse involving such substances as tobacco, drugs, and alcohol interferes with the body's normal release and uptake of neurotransmitters. For example, nicotine acts like ACTH and dopamine. Methamphetamine mimics dopamine. PCP interferes with glutamate receptors. MDMA mimics serotonin.
In most cases, the brain's responses reinforce use of the substance. Over time, the body demands more of it until the person becomes addicted.
Intelligence, Learning, and Memory
Jean Piaget, a famous psychologist, defined intelligence as "what you use when you don't know what to do." Another definition describes intelligence as mental self-management. Intelligence shows itself in how we perform in academic and creative endeavors, as well as in how we use common sense. In his book Emotional Intelligence, Daniel Goleman characterized the way we manage emotions as a form of intelligence, too.
An ongoing debate focuses on how much intelligence is inherited and how much is acquired from the environment. While there appears to be some genetic component to brain development and intelligence, early learning experiences, nurturing, and other factors play important roles, too.
Learning is the process of using the brain to acquire knowledge and skills. If you pay attention in class and do homework, then you should learn the course material. But schoolwork isn't the only thing you learn in life. Your experiences and people around you significantly affect how you learn to deal with different situations.
Language provides a fascinating look at learning. Language involves not only memorizing vocabulary words, but also applying rules for grammar and meaning. Interestingly, Steven Pinker, a researcher at the Massachusetts Institute of Technology, found that young children acquire regular grammar rules almost instinctively. For example, a normal 3-year-old might say "heared" instead of "heard" and "breaked" instead of "broke." But as he continues to speak and listen, he'll learn to use the correct words. As children grow, they acquire the ability to handle irregular verbs and more complex grammar rules. They also learn to speak abstractly, so that words acquire meanings that are both literal (a broken dish) and figurative (a broken heart).
To take advantage of learning, you need to recall information at the appropriate time, and that's where memory comes in. Like a computer, the brain constantly processes data gained through the body's senses. Unlike a computer, however, the brain is selective about what it does with all the data it's fed. Some information gets stored on a long-term basis. Other data get discarded.
Experiences may affect memory abilities. In one study, researchers analyzed London taxi drivers' spatial recall, which refers to their ability to remember things such as streets, addresses, neighborhoods, buildings, and distances. The scientists found that the hippocampus region inside the drivers' brains tended to be larger than in control subjects (people in the study who were not taxi drivers). Drivers who'd been at their jobs the longest showed the greatest increase. In other words, the job-related need to recall directions and routes may have influenced changes in the drivers' brains.
What about gender influences? Are males smarter than females, or vice versa?
His Brain vs. Her Brain
The average man's brain weighs about 11 percent more than the average woman's brain. Of course, men also tend to weigh more than women, and brain size doesn't equal intelligence. Moreover, men and women generally have the same number of brain cells.
But there are differences. Some studies show that males, on average, tend to perform better in certain spatial abilities, target-directed motor skills (such as darts), and mathematical reasoning tests. Females, on the other hand, often perform better at certain language skills, matching tests, fine motor skills, and mathematical calculation tests. In one language skills study, most men relied on their brain's right side, while women used both sides.
It's unclear how much such differences are due to genetics. Sex-related hormones seem to play a role in brain development even early in life. At the same time, brain plasticity may be triggered by subtle gender biases in society.
In any case, studies report that men and women have the same average IQ. Thus, one gender is just as smart as the other.
Staying Flexible
Can you teach an old brain new tricks? Despite its highly organized structure, the brain is adaptable--a feature called brain plasticity.
After a stroke, for example, patients sometimes "relearn" speech or certain movements. Therapy encourages healthy parts of the brain to assume functions previously done by damaged brain areas. In other cases, young people who have had parts of their brains removed for medical reasons function almost normally.
In one recent experiment, researchers "rewired" sight and hearing centers in ferrets' brains. To their surprise, the ferrets functioned normally. The research suggests that the brain may be even more adaptable than people previously thought.
Other research challenges the long-held belief that nerve cells never reproduce or grow back. In one study, scientists who studied brains of dead throat cancer patients found evidence of relatively new neurons in the hippocampus, which is part of the brain's limbic system. The findings may someday help doctors treat conditions involving nerve cell damage.
Handle with Care
In the field of neuroscience, brain research offers new possibilities for treating illnesses and injuries and simply understanding the enormous complexity of the brain. On an individual level, all sorts of possibilities are open to you, too, as a teen whose brain is still developing. Help yourself by remembering these points:
* Besides exercising your body, be sure to exercise your mind. Seek out mental challenges and variety to help stimulate and maintain healthy neural connections. They're the best way to beat off boredom.
* Make wise lifestyle choices. To prevent head injury, wear seat belts while driving and recommended helmets for biking, horseback riding, football, and other sports.
* Avoid tobacco, alcohol, and illegal drugs. They can destroy brain cells and interfere with your brain's neurotransmitters and normal brain development. They can impair memory and learning ability.
Your maturing brain is your body's command center, and you need it for life. Take good care of it, and it will take care of you.
How to Improve Your Memory
How many of these facts can you recall in one minute?
1. Where you went for vacation three years ago
2. Your mother's birthday
3. Which years World War I took place
4. Major party presidential candidates in 1992
5. Major party presidential candidates for 2000
6. Your best friend's phone number
7. Your doctor's phone number
8. Your final grade in English two years ago
9. What you ate for dinner last night
10. Chemical symbols for potassium, gold, iron, and neon
Chances are you remembered your friend's phone number faster than your doctor's. Your brain recalls that number because you've undoubtedly punched it out on the phone much more often than your doctor's.
How well you know the chemistry symbols and the years of World War I depends on whether you have learned those facts and when you last needed to use them. It may also depend on whether you enjoy history or science.
On the surface, memory may seem fickle. You might recall the lyrics to "The Ballad of Gilligan's Island" after watching a few old re-runs. On the other hand, you may scratch your head when a geometry test calls for the formula for calculating the volume of a cylinder. Fortunately, practice may help improve memory skills.
Instead of cramming before a big test, for example, review material frequently in short study sessions throughout the semester. If possible, involve multiple senses. Don't just look at the Spanish vocabulary words in the book. Say them aloud so you hear them. A trip to the language lab helps, too. The more mental connections you can make, the better.
The brain also remembers meaningful information better than abstract information. Try to understand the formula for measuring a cylinder's volume. Also think of examples where you'd use the formula, such as figuring out how much of your favorite ice cream would fit inside a round canister.
To remember such things as people's names, repeat their names out loud as you are introduced. Try to use their names in conversation. Pay attention to their appearance, voice, and the thoughts and opinions they express. Use these clues to help you associate personal characteristics with their names.
Of course, if you can't recall someone's name afterward, don't be afraid to ask it again. You're helping not only your memory, but also what could be the start of a new friendship.
Brainy Stuff
Your brain's working cells are its billions of neurons, or nerve cells. Neurons are also packed into the spinal cord and reach throughout the body. Other brain cells, called neuroglial cells, service neurons by helping to feed, protect, and clean up after them.
But the brain isn't just a mass of cells. It's divided into three major areas: the brain stem, cerebellum, and cerebrum.
Brain Stem: Your body's automatic pilot. It regulates many of your body's functions, such as breathing, heartbeat, blood pressure, digestion, and swallowing. It includes the medulla oblongata, pons, and midbrain.
Cerebellum: Coordinates muscle activity and muscle tone. Also helps you maintain posture and balance.
Cerebrum: The brain's thinking and feeling centers. Each hemisphere (half) has four surface lobes:
* Frontal lobes: Control conscious thought and planning.
* Parietal lobes: Help you feel different sensations.
* Occipital lobes: Process visual information.
* Temporal lobes: Have areas responsible for hearing, speech, and memory.
Limbic System: Parts of the cerebrum near the center of the brain combine with the thalamus and hypothalamus to form the limbic system. It plays an important role in learning, memory, and emotions.
Corpus Callosum: Transmits messages between the brain's two hemispheres.
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Imaging the Brain
High-tech imaging has given scientists new insights into the brain. Noninvasive techniques to scan and detect brain activity include:
Magnetic resonance imaging (MRI)--After magnetism aligns the body's atomic particles, atoms return to their initial state and emit weak radio waves. Computerized tomography (CT) equipment interprets those signals and generates a three-dimensional picture.
Functional MRI (fMRI)--This advancement on MRI uses rapid scanning to focus on areas with the most oxygen (and hence the most brain activity).
Positron-emission tomography (PET)--Using a radioactive marker, PET also highlights areas of the brain that are working hardest.
Near-infrared spectroscopy (NIRS)--NIRS measures reflections from low-level light waves beamed into the brain.
Electroencephalography (EEG)--EEG measures electrical patterns detected from various sensors placed on a subject's head.
Magnetoencephalography (MEG)--Similar to EEG, MEG detects magnetic pulses emitted by neurons as they fire.
for more information
Visit these Web sites for more information on the brain:
Dana BrainWeb-- http://www.dana.org/brainweb
National Institute on Drug Abuse-- "Mind Over Matter";
http://www.nida.nih.gov/MOM/MOMIndex.html
Neurosciences on the Internet-- http://www.neuroguide.com
Neuroscience for Kids-- http://faculty.washington.edu/chudler/ neurok.html