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When you want to know "why" your parents won't let you do things that you want to do...
the following information explains why you need to listen to them. But WAIT!!!
The reason your parents don't want you to do whatever it is that you want to do may be different than what you are about
to read. They may just think you're not ready to do whatever it is you want to do... and they might be right about that -
but if you WOW them with the real reasons you're wired differently than they think you are!
Just let them in on this information!
  An interview with Jay Giedd: Giedd is a neuroscientist at the National Institute of Mental Health
What has surprised you about looking at the adolescent brain?
The most surprising thing
has been how much the teen brain is changing. By age 6, the brain is already 95% of its adult size. But the gray matter, or
thinking part of the brain, continues to thicken throughout childhood as the brain cells get extra connections, much like
a tree growing extra branches, twigs and roots.
In the frontal part of the
brain, the part of the brain involved in:
- judgment
- organization
- planning
- strategizing
those very skills that teens get better and better at - this process of thickening of the gray matter peaks at about age 11 in
girls and age 12 in boys, roughly about the same time as puberty.
After that peak, the gray
matter thins as the excess connections are eliminated or pruned. So much of our research is focusing on trying to understand
what influences or guides the building-up stage when the gray matter is growing extra branches and connections and what guides
the thinning or pruning phase when the excess connections are eliminated.
as you're reading thru these articles... and it gets kinda boring... just think
about how complicated the human brain is...
it's much more complicated than teenagers would like to think.... now remember
those commercials on television... "this is your brain on drugs" ????
imagine how complicated things can get when you start messing with your brain
while it's finishing its development by experimenting with drugs and alcohol!
And what do you think this might mean, this exuberant growth of those early adolescent years?
I think the exuberant growth
during the pre-puberty years gives the brain enormous potential. The capacity to be skilled in many different areas is building
up during those times.
What the influences are of:
- parenting or teachers
- society
- nutrition
- bacterial and viral infections
- all these factors - on this building-up phase, we're just
beginning to try to understand.
But the pruning-down phase
is perhaps even more interesting, because our leading hypothesis for that is the "Use it or lose it"
principle. Those cells and connections that are used will survive and
flourish. Those cells and connections that are not used will wither and die.
So if a teen is doing music
or sports or academics, those are the cells and connections that will be hard-wired. If they're lying on the couch or playing
video games or MTV, those are the cells and connections that are going [to] survive.
Right around the time
of puberty and on into the adult years is a particularly critical time for the brain sculpting to take place. Much like Michelangelo's
David, you start out with a huge block of granite at the peak at the puberty years.
Then the art is created
by removing pieces of the granite, and that is the way the brain also sculpts itself. Bigger isn't necessarily better, or
else the peak in brain function would occur at age 11 or 12. ...
The advances come from actually taking away and pruning down of certain connections themselves.
The frontal lobe is often called the CEO, or the executive of the brain.
It's involved in things like:
- planning
- strategizing
- organizing
- initiating attention
- stopping & starting & shifting attention
It's a part of the brain
that most separates man from beast, if you will. That is the part of the brain that has changed most in our human evolution,
and a part of the brain that allows us to conduct philosophy and to think about thinking and to think about our place in the
universe. ...
I think that [in the teen years, this] part of the brain that is helping organization, planning and strategizing
is not done being built yet ... [It's] not that the teens are stupid or
incapable of [things].
It's sort of unfair to expect them to have adult
levels of organizational skills or decision making before their brain is finished being built. ...
It's also a particularly cruel
irony of nature, I think, that right at this time when the brain is most vulnerable is also the
time when teens are most likely to experiment with drugs or alcohol.
Sometimes when I'm working
with teens, I actually show them these brain development curves, how they peak at puberty and then prune down and try to reason
with them that if they're doing drugs or alcohol that evening, it may not just be affecting their brains for that night or
even for that weekend, but for the next 80 years of their life. ...
Tell me a little bit about how the brain develops.
How does the brain -- arguably the most complicated three-pound
mass of matter in the known universe -- how does the brain become the brain? It does so through two simple but powerful processes.
The first one is over-production. The brain produces way more
cells and connections than can possibly survive. There's only so many nutrients, there's only so many growth factors, there's only so much room in the skull. After this vast over-production,
there is a fierce, competitive elimination, in which the brain cells and connections fight it out for survival. Only a small
percentage of the cells and connections make it.
This is a process that we knew happened in the womb, maybe even
the first 18 months of life. But it was only when we started following the same children by scanning their brains at two-year
intervals that we detected a second wave of over-production. This second wave of over-production is manifest by an actual
thickening in the gray matter, or the thinking part, in the front part of the brain.
As this second wave of over-production is occurring, it prepares
the adolescent brain for the challenges of entering the next stage of life, the adult years. There's enormous potential at
that time. People can take many different life directions. But about around that time of puberty, people start specializing,
so to speak. They start deciding, "This is what I'm going to be good at, whether it be sports or academics or art or music."
All the life choices, even though they are still there, start getting whittled away, and we have to start sort of focusing
in on what makes us unique and special. ...
Do you have particular concerns about that period, too, though?
Yes. It's a time of enormous opportunity and of enormous risk.
And how the teens spend their time seems to be particularly crucial. If the "Lose it or use it" principle holds true, then
the activities of the teen may help guide the hard-wiring, actual physical connections in their brain. ...
Can you describe to me what people used to believe about the brain, actually, very recently?
One of the most exciting discoveries from recent neuroscience
research is how incredibly plastic the human brain is. For a long time, we used to think that the brain, because it's already
95 percent of adult size by age six, things were largely set in place early in life. ... [There was the] saying. "Give me
your child, and by the age of five, I can make him a priest or a thief or a scholar."
[There was] this notion that things were largely set at fairly
early ages. And now we realize that isn't true; that even
throughout childhood and even the teen years, there's enormous capacity for change. We think that this capacity for change
is very empowering for teens. ...
This is an area of neuroscience that's receiving a great deal
of attention ... the forces that can guide this plasticity. How do we optimize the brain's ability to learn? Are schools doing a good job? Are we as parents doing a good job? And the challenge
now is to ... bridging the gap between neuroscience and practical advice for parents, teachers and society. We're not there
yet, but we're closer than ever, and it's really an exciting time in neuroscience. ... The next step will be, what can you
do about it, what can we do to help people? What can we do to help the teen optimize the development of their own brain? ...
There has been a great deal of attention on the early years, and particularly on stimulating
the early brain. What do you think of that work and that popularization of that brain science?
There's been a great deal
of emphasis in the 1990s on the critical importance of the first three years. I certainly applaud those efforts. But what
happens sometimes when an area is emphasized so much, is other areas are forgotten.
And even though the first 3 years are important, so are the
next 16. And the ages between 3 and 16, there's still enormous dynamic activity happening in brain biology. I think that that
might have been somewhat overlooked with the emphasis on the early years. ...
Not so long ago, people were emphasizing teaching little children through flashcards,
through particular kinds of mobiles with black-and-white checks on them, playing Mozart. In fact, some states have sent CDs
back with new mothers. What do you think of that? Has that been a misinterpretation of brain science?
... We all want to do the
best for our children. And what I fear is happening is that we're leaping too far from the neuroscience to such things. I
don't think there is any established videotape or CD or computer program or type of music to play that we've shown with any
scientific backing to actually help our children.
The more technical and more
advanced the science becomes, often the more it leads us
back to some very basic tenets of spending loving, quality time with our children. The brain is largely wired for social interaction
and for bonding with caretakers. And sometimes it's even disappointing to people that, with all the science and all the advances
the best advice we can give is things that our grandmother could have told us generations ago: to spend loving, quality time
with our children. ... I think [it] probably does more harm than good for parents
to be confronted with so many of these conflicting reports in the media without any scientific basis. ...
What directions is the research taking to explore how we can optimize brain development?
Now that we've been able to
detect the developmental path of different parts of the brain, the next phase of our research is to try to understand what
influences these brain development paths. Is it nutrient or parenting or video games or the activity of the [child]? Or is
it genes? By studying twins, we can begin to address some of these very basic nature/nurture-type of questions.
For instance, when twins are
in the first grade, their parents often dress them in the
same clothes. They get the same haircut. It's sort of cute how alike they are. But that's not as cool in high school anymore.
And so a lot of the twins as teens in high school start doing different things. The one who was a little bit better in sports
may become an athlete. The one who was a little bit better at academics may become a scholar. Or one may turn to music and
one to art. But they often have different daily activities.
So we can scan the brains
when the twins are young and doing everything very much alike; then we can scan them as teenagers, when they start having
different daily activities. This gives us a sense of which parts of the brain are influenced by behavior and which parts by the genes themselves.
We've already got some interesting
early data on this. One part of the brain is called the corpus callosum. It's a thick cable of nerves that connects that two
halves of the brain and is involved in creativity and higher type of thinking. It's very popular for imaging studies because
it leaps out of the picture. It's very easy to measure and
quantify.
It's also interesting
because it changes a lot throughout childhood and adolescence. It's been reported to be different in size and shape in many
different illnesses that happen during childhood ... many higher cognitive thought [processes] like creativity and ability
to solve problems. So it's been of great interest, especially to child psychiatrists. And what we find is that the size and
shape of the corpus callosum is remarkably similar amongst twins ... and [so]
seems to be surprisingly under the control of the genes.
But another part of the brain
- the cerebellum, in the back of the brain - is not very genetically controlled. Identical twins' cerebellum are no more alike
than non-identical twins. So we think this part of the brain is very susceptible to the environment. And interestingly, it's
a part of the brain that changes most during the teen years. This part of the brain has not finished growing well into the
early 20s, even. The cerebellum used to be thought to be
involved in the coordination of our muscles. So if your cerebellum is working well, you were graceful, a good dancer, a good
athlete.
But we now know it's also
involved in coordination of our cognitive processes, our thinking processes. Just like one can be physically clumsy, one can
be kind of mentally clumsy. And this ability to smooth out all the different intellectual processes to navigate the complicated social life of the teen
and to get through these things smoothly and gracefully instead of lurching ... seems to be a function of the cerebellum.
And so we think it's intriguing
that we see all these dynamic changes in the cerebellum taking place during the teen years, along with the changes in the
behaviors that the cerebellum sub-serves.
What would influence the development of the cerebellum?
Traditionally it was thought that physical activity would most influence the cerebellum, and
that's still one of the leading thoughts. It actually raises thoughts about, as a society, we're less active than we ever
have been in the history of humanity. We're good with our thumbs and video games and such. But as far as actual physical activity,
running, jumping, playing, children are doing less and less of that, and we wonder, long term, whether that may have an effect
on the development of the cerebellum.
The recess and play seems to be the first thing that is cut
out of school curriculums in tight times. But those actually may be as important, or maybe even more important, than some
of the academic subjects that the children are doing. ... We think that the "Use it or lose it" principle holds for the cerebellum
as well. If the cerebellum is exercised and used, both for physical activity but also for cognitive activities, that it will
enhance its development.
... One analogy that computer people use is that [the cerebellum
is] like a math co-processor. It's not essential for any activity. People can get by quite well without large chunks of it.
But it makes many activities better. The more complicated the activity, the more we call upon the cerebellum to help us solve
the problem. And so almost anything that one can think of as higher thought -- mathematics, music, philosophy, decision making,
social skills -- seems to draw upon the cerebellum. ...
The relationship between the findings that we have in the cerebellum
and sort of practical advice or the links between behavior are
not well worked out yet. That's going to be one of the great challenges of neuroscience -- to go from these neuroscience facts
to useful information for parents, for teachers or for society. But it's just so recently that we've been able to capture
the cerebellum that no work has yet been done on the forces that will shape the cerebellum or the link between the cerebellum
shape or size and function.
When you look at the recent work that you've done in terms of the frontal cortex,
do you see a difference between girls and boys?
Yes. One of the things that
we're particularly interested in as child psychiatrists is the difference between boys' brains and girls' brains, because
nearly everything that we look at as child psychiatrists is different between boys and girls - different ages of onset, different
symptoms, different prevalences and outcomes. Almost everything in childhood is more common in boys - autism, dyslexia, learning
disabilities, ADHD, Tourette's syndrome - are all more common in boys. Only anorexia nervosa is more common in girls. So we
wonder if the differences between boys' and girls' brains might help explain some of these clinical differences.
The male brain is about 10%
larger than the female brain across all the stages of ... 3 to 20; not to imply that the increased size implies any sort of
advantage, because it doesn't. The IQs are very similar. But there are differences between the boy and girl brains, both in
the size of certain structures and in their developmental path. The basal ganglia which are a part of the brain that help
the frontal lobe do executive functioning are larger in females, and this is a part of the brain that is often smaller in
the childhood illnesses. I mentioned, such as ADD and Tourette's syndrome.
So girls, by virtue of having
larger basal ganglia, may be afforded some protection against these illnesses. But in the general trend for brain maturation,
it's that girls' brains mature earlier than boys' brains. ...
source site: click here
 did you know? (from pbs.com - the brain)
The Teenage Brain
A World of Their Own
When examining the adolescent brain we find mystery, complexity, frustration, and inspiration. As the brain begins teeming with hormones, the prefrontal cortex, the center of reasoning and impulse control,
is still a work in progress.
For the first time, scientists
can offer an explanation for what parents already know - adolescence is a time of roiling
emotions, and poor judgment.
Why do teenagers have distinct
needs and behaviors? Why, for example, do high school students have such a hard time waking up in the morning?
Scientists have just begun
to answer questions about the purpose of sleep as it relates to the sleep patterns of teenagers.
  If you try to make a list
of the things you did in the last 15 years, it would probably look like this:
- three years in junior-high
- 20 months with your boyfriend
- a year of study in Italy
Forgetting anything? As a
matter of fact, you are leaving out the one thing that you spent the most time doing. Sleep.
This major time consumer took
about five years from the past 15.
While adults spend
about 1/3 of their time sleeping, babies and toddlers sleep away 1/2
of their early childhood.
It cannot be the
terrible waste of time that it seems. Or can it be? Embarrassingly, scientists still cannot persuasively point out the biological
function of sleep.
Sex, eating, and
sleeping constitute the triad of basic impulses of human beings. Yet, while the functions of the first two have been obvious
for millennia, it is not clear why we crave to spend a third of our life in bed.
Over
the past decade, new findings that may lead to the resolution of this conundrum have been accumulating. Many scientists believe
that in a few years we will understand not just why we sleep, but also what biochemical mechanisms underlie this odd activity.
The brain during sleep may review and sort the knowledge that it has encountered
during the day.
The first few hints for
the function of sleep came from observations on animals. All mammals sleep, as do birds and even bees. One theory suggests
that sleep is a simple protection mechanism, a way to keep animals quiet and still, so that they attract less attention, and
thus are less noticeable to predators.
This stillness is particularly
important when the animal is most vulnerable, which for many animals, is during the dark of night. But comparing sleep patterns
of different species suggests that this may be too simplistic an explanation.
Opossum, for example, sleep up to 20 hours a day. Giraffes,
on the other hand, spend no more than 20 minutes a day sleeping, and don't even bother to recline their cumbersome bodies.
Dolphins and whales also spend a very short time sleeping, and
continue to swim even as they catch their Zs.
Some scientists even claim
that dolphins let only half of their brain sleep at a time. This diversity of sleeping patterns implies that sleep is more
than just a way of keeping animals quiet. There must be another explanation.
Clearly,
sleep is an opportunity to rest. Hence, many theorists have hypothesized that the main purpose of sleep is to enable the muscles
and the brain to recuperate after a busy day. But measuring the electric activity of the brain unveils the shortcomings of
this theory:
A sleeping brain is far from dormant.
When measured using
EEG, the electric activity of a brain when asleep is no less hectic than it is when awake. There is a difference, though,
between two different phases of sleep. Right after falling asleep, the brain demonstrates slow EEG activity. This stage is
called slow wave sleep (SWS). However, after a while, the brain goes into the turmoil of the second stage, which due to its
similarity to the brain activity of attentive wakefulness, is known as paradoxical sleep. In this stage, the EEG reveals very
fast activity. At the same time, the eyes move rapidly, giving this stage its other famous name -- REM (Rapid Eye Movement)
sleep. REM sleep is also the time during which we dream.
A number of fascinating experiments suggest that this jittery second stage is the daily session
of memory maintenance and that during this time, the brain reviews and sorts the knowledge that it has encountered during
the day. Some of it is discarded and some of it is stored in the appropriate context. According to this theory, sleep is required for learning and memory.
In a few experiments, rats were trained to find their way through a maze while electrodes were recording the
activity of their brain. When the rats fell asleep, the brain started to behave oddly. In light of difficulties of getting
a clear verbal description from the rats regarding their dreams, we can rely only on the pattern of their brain activity.
The rats' brain activity during sleep was highly similar to the activity during the training. The brain seemed to reconstruct
the experience of the day. In their dreams, the rats were again chasing the cheese through the maze.
Other experiments supplied more direct evidence that sleep
is crucial for learning. Human subjects were trained to identify letters that appeared for a blink of an eye on a computer
screen. Then, half of the subjects were sent home to sleep, while the other half were deprived of sleep for the entire night,
and only then went home to rest. Two days later when all the subjects were already rested and refreshed, the scientists checked
their ability to read the flashing letters. None of the participants were tired, and yet the people who went to sleep right
after the training performed much better than the ones who went to sleep a day later. This suggests that the night sleep immediately
after the activity was crucial for gaining the most from the training session. Without it, the training was much less effective.
The fact that during their formative years of childhood
and adolescence, people sleep much more than during their adulthood, also supports the
view that sleeping plays a role in learning. Yet, some scientists claim that this evidence is still weak, and more importantly,
that other experiments yield contradicting results. Therefore, they argue, declaring that the mystery
of sleep is resolved, and that the main function of sleep is to enhance learning,
would be premature.
Only future research can decide this debate. In the mean time, if you are planning to pull an
all-nighter before a big test, you may want to reconsider. When you go to sleep your brain may still be studying. Perhaps
this night session is as crucial for your success as the learning you do when you are awake.
Written
by Yanay Ofran.
If you are interested in reading your horoscope... here's the thingie~
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Adolescent
Sleep Needs and Patterns
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To learn more about cutting-edge research on teen sleep, and to find
sleep tips and resources for school start time issues, download and read Adolescent
Sleep Needs and Patterns.
The National Institutes of Health (NIH) have identified adolescents
and young adults (ages 12 to 25 years) as a population at high risk for problem sleepiness based on "evidence that the prevalence
of problem sleepiness is high and increasing with particularly serious consequences." (NIH, 1997) This designation evolved
from a Working Group on Problem Sleepiness convened in 1997 by NIH's National Center on Sleep Disorders Research and the Office
of Prevention, Education, and Control. The group concluded that steps must be taken to reduce the risks associated with problem
sleepiness.
What are these risks? The most troubling consequences of sleepiness
are injuries and deaths related to lapses in attention and delayed response times at critical moments, such as while driving.
Drowsiness or fatigue has been identified as a principle cause in at least 100,000 police-reported traffic crashes each year,
killing more than 1,500 Americans and injuring another 71,000, according to the National Highway Traffic Safety Administration
(NHTSA, 1994). Young drivers age 25 or under are involved in more than one-half of fall-asleep crashes.
The National Sleep Foundation's (NSF) Sleep And Teens Task Force developed
this report to summarize existing research about sleep-related issues affecting adolescents. We hope that this report will
serve as a valuable and practical resource for parents, educators, community leaders, adolescents and others in their efforts
to make informed decisions regarding health, safety and sleep-related issues within their communities.
A nonprofit, private organization, NSF is a leader in public education
efforts regarding the risks associated with drowsy driving and other issues related to sleepiness and sleep loss. We welcome
your comments about this report and your suggestions for expanding public awareness and supporting positive changes to protect
the safety and well-being of our nation's youth.
source site: click here |
PHYSIOLOGICAL PAT T E R N S
Adolescents require
at least as much sleep as they did as pre-adolescents (in general, 8.5 to 9.25 hours each night).
(Carskadon et al., 1980)
Daytime sleepiness
increases - for some, to pathological levels - even when an adolescent’s schedule provides for optimal amounts of sleep. (Carskadon, Vieri, Acebo, 1993)
Adolescents’ sleep
patterns undergo a phase delay, that is, a tendency toward later times,
for both sleeping and waking. Studies show that the typical high school student’s natural time to fall asleep is 11:00 pm or later. (Wolfson and Carskadon,
1998)
B E H AVIORAL AND PSYCHOSOCIAL PAT T E R N S
Many U.S. adolescents
do not get enough sleep,
especially during the week. Survey data show that average total
sleep time during the school week decreases from 7 hours, 42 minutes in
13 year olds to 7 hours, 4 minutes in 19 year olds. (Wolfson and Carskadon, 1998) Only 15% of adolescents reported sleeping 8.5 or more hours on school nights, and 26%
of students reported typically sleeping 6.5 hours or less each school night.
Adolescents have irregular sleep patterns;
in particular, their weekend sleep schedules are much different
than their weekday schedules, to some extent as a direct consequence of weekday sleep
loss. These differences include both the quantity and the timing of sleep. One study of more than 3,000 adolescents showed that the average increase of weekend over weekday sleep across ages 13-19
was one hour and 50 minutes. (Wolfson and Carskadon, 1998) In 18-year-olds, the average
discrepancy was more than two hours. In addition, 91 percent of
the surveyed high school students reported going to sleep after 11:00 pm on weekends, and 40 percent went to bed after 11:00
pm on school nights.
Irregular sleep schedules -
including significant discrepancies between weekdays and weekends
- can contribute to a shift in sleep phase (i.e., tendency toward morningness or eveningness), trouble
falling asleep or awakening, and fragmented (poor quality) sleep. (Dahl and Carskadon, 1995)
source site: click here
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need a shoulder to lean on?
need someone to vent to?
Adolescent Brains Are Works In Progress
by Sarah Spinks
And here's why...
Over the past 25 years, neuroscientists have discovered
a great deal about the architecture and function of the brain. Their discoveries have led to huge strides in medicine, from
pinpointing the timing at which children should be operated on for vision problems to shedding light on the mechanisms that
cause such diseases as schizophrenia. Much of the early focus of the research was on the early years of development or on
diseased brains. Now, with the advent of new imaging techniques, researchers are able to examine normal brains and brains
of people throughout their lives.
Before the advent of magnetic resonance imaging (MRI), scientists
already knew a lot about how the brain functioned. When people suffered brain damage or injury to particular parts of the
brain, scientists could see what functions were impaired, and infer that the injured areas governed those functions. For example,
people who had strokes in the area of the brain affecting speech lost the ability to speak. Autopsies showed when particular
parts of the brain matured, the connections were wrapped in white matter, or myelin.
With functional MRIs, researchers can see how the brain
actually functions -- what parts of the brain use energy when performing certain tasks. They know, for instance, the particular
part of the brain that "lights up" when performing a visual task. Those images in which brain activity is measured are called
"functional" because they measure how the brain performs tasks rather than simply mapping out the structure of the brain.
FRONTLINE's "Inside the Teenage Brain" focuses on work done
by Dr. Jay Giedd at the National Institute of Mental Health in Bethesda, Md., together
with colleagues at McGill University in Montreal. In a particularly interesting study, Dr. Giedd looked at the brains of 145
normal children by scanning them at two-year intervals. This was work Giedd was only able to do with magnetic resonance imaging,
because it requires neither harmful dyes nor radiation, making the study of normal children, as opposed to sick ones, ethically
tenable.
What the researchers have found has shed light on how the brain
grows and when it grows. It was thought at one time that the foundation of the brain's architecture was laid down by the time
a child is five or six. Indeed, 95 percent of the structure of the brain has been formed by then. But these researchers have
discovered changes in the structure of the brain that appear relatively late in child development.
Changes in the Prefrontal Cortex
Giedd and his colleagues found that in an area of the brain
called the prefrontal cortex, the brain appeared to be growing again just before puberty. The prefrontal cortex sits just
behind the forehead. It is particularly interesting to scientists because it acts as the CEO of the brain, controlling planning,
working memory, organization, and modulating mood. As the prefrontal cortex matures, teenagers can reason better, develop
more control over impulses and make judgments better. In fact, this part of the brain has been dubbed "the area of sober second
thought."
The fact that this area was still growing surprised the scientists.
Although they knew that the brain of a baby grew by over-producing synapses, or connections, they had not known that there
was a second period of over-production. In a baby, the brain over-produces brain cells (neurons) and connections between brain
cells (synapses) and then starts pruning them back around the age of three. The process is much like the pruning of a tree.
By cutting back weak branches, others flourish. The second wave of synapse formation described by Giedd showed a spurt of
growth in the frontal cortex just before puberty (age 11 in girls, 12 in boys) and then a pruning back in adolescence.
Even though it may seem that having a lot of synapses is a particularly
good thing, the brain actually consolidates learning by pruning away synapses and wrapping white matter (myelin) around other
connections to stabilize and strengthen them. The period of pruning, in which the brain actually loses gray matter, is as
important for brain development as is the period of growth. For instance, even though the brain of a teenager between 13 and
18 is maturing, they are losing 1 percent of their gray matter every year.
Giedd hypothesizes that the growth in gray matter followed by
the pruning of connections is a particularly important stage of brain development in which what teens do or do not do can
affect them for the rest of their lives. He calls this the "use it or lose it principle," and tells FRONTLINE, "If a teen
is doing music or sports or academics, those are the cells and connections that will be hardwired. If they're lying on the
couch or playing video games or MTV, those are the cells and connections that are going to survive."
Corpus Callosum and Cerebellum
In another study of growth patterns of the developing brain,
Paul Thompson of the University of California at Los Angeles, along with Jay Giedd and colleagues from McGill University,
found waves of growth in the corpus callosum, a fiber system that relays information between the hemispheres of the brain.
Of particular interest to educators and parents is their finding that the fiber systems influencing language learning and
associative thinking grew more rapidly than surrounding regions before and during puberty (a similar period to the growth
of the frontal cortex), but fell off shortly after. These findings reinforce studies on language acquisition that show that
the ability to learn new languages declines after the age of 12. [1]
These studies of the corpus callosum are part of a large multi-centered
research study on twins. Researchers are hopeful that twin studies will also shed light on the age-old question of nature
or nurture -- which traits and characteristics are due to genetics and which can be affected by the environment. For instance,
the studies have shown that the corpus callosi of twins are so similar that one can put 10 twin brain MRIs on view and even
a novice can spot the pairs. The researchers therefore hypothesize that this part of the brain is largely controlled by genes.
However, another piece of neuroanatomy, the cerebellum, at the back of the head just above the neck, is not very similar in
twins, leading Giedd to hypothesize that the cerebellum is not genetically controlled and is thus susceptible to the environment.
Interestingly, the cerebellum is a part of the brain that changes
well into adolescence. Scientists think the cerebellum helps in physical coordination. But looking at functional imaging studies
of the brain, researchers also see activity in the cerebellum when the brain is processing mental tasks. Giedd thinks it works
like this: "It's like a math co-processor. It's not essential for any activity ... but it makes any activity better. Anything
we can think of as higher thought, mathematics, music, philosophy, decision-making, social skill, draws upon the cerebellum.
... To navigate the complicated social life of the teen and to get through these things instead of lurching seems to be a
function of the cerebellum."
Cautionary Words
Jay Giedd and his colleagues have given us a new window into
understanding how the pre-adolescent brain develops. It confirms what other neuroscientists have outlined over the past 25
years -- that different parts of the brain mature at different times. In particular, it corroborates the work of neuroscientists
like Peter Huttenlocher who have shown that the frontal cortex of human beings matures relatively late in a child's life.
However, knowing more about the structure of the brain
does not necessarily tell us more about the function of the brain. It is a good hypothesis that if a particular structure
is still immature, the functions it governs will show immaturity. Thus, there is fairly widespread agreement that adolescents
take more risks at least partly because they have an immature frontal cortex, because this is the area of the brain that takes
a second look at something and reasons about a particular behavior. However, moving from structure to function, deciding what
behavior is caused by what part of the brain is much more complicated.
Jack Shonkoff, professor of child development at Brandeis
University and author of From Neurons to Neighborhoods, warns policymakers to be careful about interpreting the findings
of neuroscientists too simplistically. In his interview with FRONTLINE, Shonkoff says, "The caution is really to be careful
about what's not quite ready for prime time yet in terms of application."
John Bruer, the author of The Myth of the First Three
Years and the president of the James S. McDonnell Foundation, is more blunt. Says Bruer: "This simple, popular, newsweekly-magazine
idea that adolescents are difficult because their frontal lobes aren't mature is one we should be very cautious of. Yes, there
are adolescents that are hard to get along with. There are adults that are hard to get along with for the same reason. Presumably,
the adults have mature frontal areas. There are very young children who seem to have no problem with this. Very immature brain
structure, yet results in very sophisticated behavior. So this notion there's going to be some easy connection between counting
synapses or measuring white matter and the kinds of behaviors people display or we want them to display is one we're going
to have to do a lot more work on before it's science."
Despite the caveats about how much we can know about brain function
and how readily any of this work can be translated into policy, it is clear from the research that the brain is a good deal
more plastic or changeable than we once thought. Important structural changes are taking place well into adolescence and beyond.
Except for a few well-defined sensitive periods for certain types of vision, hearing, and first-language learning, the brain
is capable of growth well beyond the first few years of life. An important part of the growth is happening just before puberty
and well into adolescence. The brain research adds new dimensions to our understanding of adolescence -- a time of both heightened
opportunity and risk.
[1] Nature, Volume 404, March 9, 2000.
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One Reason Teens Respond Differently to the World: Immature Brain Circuitry
by Sarah Spinks
We used to think that teens respond differently to the world
because of hormones, or attitude, or because they simply need independence. But when adolescents' brains are studied through
magnetic resonance imaging (MRI), we see that they actually work differently than adult brains.
At the McLean Hospital in Belmont, Mass., Deborah Yurgelun-Todd and a group of
researchers have studied how adolescents perceive emotion as compared to adults. The scientists looked at the brains of 18
children between the ages of 10 and 18 and compared them to 16 adults using functional magnetic resonance imaging (fMRI).
Both groups were shown pictures of adult faces and asked to identify the emotion on the faces. Using fMRI, the researchers
could trace what part of the brain responded as subjects were asked to identify the expression depicted in the picture.
The results surprised the researchers. The adults correctly
identified the expression as fear. Yet the teens answered
"shocked, surprised, angry." And the teens and adults used different parts of their brains to process what they were feeling.
The teens mostly used the amygdala, a small almond shaped region that guides instinctual or "gut" reactions, while the adults
relied on the frontal cortex, which governs reason and planning.
As the teens got older, the center of activity shifted more
toward the frontal cortex and away from the cruder response of the amygdala.
Yurgelun-Todd, director of neuropsychology and cognitive neuroimaging
at McLean Hospital believes the study goes partway to understanding
why the teenage years seem so emotionally turbulent. The teens seemed not only to be misreading the feelings on the adult's
face, but they reacted strongly from an area deep inside the brain. The frontal cortex helped the adults distinguish fear
from shock or surprise. Often called the executive or CEO of the brain, the frontal cortex gives adults the ability to distinguish
a subtlety of expression: "Was this really fear or was it surprise or shock?" For the teens, this area wasn't fully operating.
Reactions, rather than rational thought, come more from the
amygdala, deep in the brain, than the frontal cortex, which led Yurgelun-Todd and other neuroscientists to suggest that an
immature brain leads to impulsivity, or what researchers dub "risk-taking behavior." Although it was known from animal studies
and brain-injured people that the frontal cortex matures more slowly than other brain structures, it has only been with the
advent of functional MRI that researchers have been able to study brain activity in normal children.
The brain scans used in these studies are a valuable tool for
researchers. Never before have scientists been able to develop data banks of normal, healthy children. Outlining the changes
in normal function and development will help researchers determine the causes of psychiatric disorders that afflict children
and adolescents.
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Adolescents and Sleep
by Sarah Spinks
In making "Inside the Teenage Brain," we seemed to hit a nerve
-- a parental one -- when we began looking into the world of teenagers and how they sleep. The patterns that young teens seemed
to be experiencing -- an inability to go to sleep at night, followed by profound drowsiness on waking -- seemed so pervasive
that it should come as no a surprise that what parents were seeing at home had already been corroborated in university sleep
labs at Stanford and Brown.
Reseachers had always believed that sleep was governed by what
was called the sleep-wake homeostasis, that is: "All other things being equal, ... the longer one is awake, the greater the
pressure for sleep to occur. ... This process accounts for the increased need for sleep after staying awake all night." [1] It seemed perfectly reasonable that people would want to
sleep when they were very tired. But it didn't account for a number of patterns that were obvious outside the lab: jet travellers
woke up at 2 a.m. despite being exhausted after flying from Boston to London, teenagers had trouble falling asleep though
they also seemed to be very tired, older people often woke up very early in the morning.
The Biological Clock
What researchers discovered is an internal biological clock,
a clock that sometimes acts against the sleep-wake cycle by keeping us alert when we should be feeling tired. Sleep researchers
Mary Carskadon, now at Brown University, and Bill Dement at Stanford had seen
this biological clock in action when they tested a group of 10-12 year olds at Stanford. Dement, who pioneered sleep research
at Stanford, wrote about these experiments: "After centuries of assuming the longer we are awake, the sleepier we will become
and the more we will tend to fall asleep, we were confronted by the surprising result that after 12 hours of being awake,
the subjects were less sleepy than they had been earlier in the same day, and at the 10 o'clock test, after more than
14 hours of wakefulness had elapsed ...they were even less sleepy." [2]
The researchers found that the biological clock opposed the
sleep-wakefulness cycle at certain points of the day and at certain ages. It kept people awake when they were very tired.
Just before puberty, that internal clock helped teens stay alert at night when they should have been falling asleep. The researchers
called this a "phase-delay."
The biological clock or circadian rhythms (from the Latin words
"circa" and "dies," or "around day") of smaller children don't show the same delays. Nothing is opposing their need to sleep
in the evening. Until the age of 10, many children wake up fresh and energetic to start the day. In contrast, the biological
clock of pre-teens shifts forward, creating a "forbidden" zone for sleep around 9 or 10 p.m. It is propping them up just as
they should be feeling sleepy. Later on, in middle-age, the clock appears to shift back, making it hard for parents to stay
awake just when their teens are at their most alert.
Carskadon discovered other important patterns in adolescent
sleep. By studying alertness, she determined that teens, far from needing less sleep, actually needed as much or more sleep
than they had gotten as children -- nine and a quarter hours. Most teenagers weren't getting nearly enough -- an hour and
a half less sleep than they needed to be alert. And the drowsiness wasn't only in the early morning. Teens had a kind of sleep
trough in the mid-afternoon and then perked up at night, even though they hadn't had a nap.
Carskadon is now exploring the effect of light in setting adolescent
sleep patterns, for darkness seems to trigger the release of melatonin, often called the "sleep" hormone. Measuring melatonin
also helps researchers define the different circadian rhythms of children, teens, and adults.
Sleep Debt
A great concern of sleep researchers is that teens are so sleep-deprived.
Bill Dement speaks about the huge sleep debt that many teens and adults carry around with them every day. With most high schools
in the U.S. starting around 7:20 a.m. and with many teens going to bed between 11 and 12 p.m., sleep researchers worry that
teenagers are suffering an epidemic that is largely hidden. Since students are often driving to school, to sporting events,
and home from late-night parties, this sleep debt holds huge risks. Many high school students know of someone, often a high-achieving
kid, who on the drive back from a sporting event or dance simply fell asleep at the wheel. On a less dramatic note, there
are literally millions of adolescents who feel despondent, get poor marks, or are too tired to join high-school teams all
because they are getting too little sleep. Because of their deep concern about these issues, sleep researchers are pushing
for later school start times and are trying to introduce sleep issues into the high school curriculum.
Sleep, Learning, and Memory
The other area of sleep research relevant to teenagers, their
parents, and teachers is the effect of sleep on learning and memory. In experiments done at Harvard Medical School and Trent
University in Canada, students go through a battery of tests and then sleep various lengths of time to determine how sleep
affects learning. What these tests show is that the brain consolidates and practices what is learned during the day after
the students (or adults, for that matter) go to sleep. Parents always intuitively knew that sleep helped learning, but few
knew that learning actually continues to take place while a person is asleep. That means sleep after a lesson is learned
is as important as getting a good night's rest before a test or exam.
This research is done by giving students a series of tests.
The students are trained, for instance, to catch a ball attached by a string to a cone-like cup. As they repeat the skill
during the test day, they are able do it faster and more accurately. Let's say they go from catching a ball 50 percent to
70 percent of the time over a period of half an hour. The students who get a good night's sleep improve when they are retested.
On a retest three days after they have a good night's sleep, they might catch a ball 85 percent of the time. The other students
who got less than six hours sleep either do not improve or actually fall behind.
Some of the tests are more demanding. They are called cognitive
procedural tasks and they mimic what a student might learn in physics or math, or in certain sports. They present the student
with something new to be learned or require an ability to conceptualize, to form a picture of the task in their minds.
The brain consolidates learning during two particular phases
of sleep. According to Dr. Robert Stickgold of Harvard University Medical School, who conducted a series of tests involving
visual tasks, the brain seems to need lots of slow-wave sleep and a good chunk of another kind of sleep, Rapid Eye Movement,
or REM. Dr. Stickgold hypothesizes that the reason the brain needs these particular kinds of sleep is that certain brain chemicals
plummet during the first part of the night, and information flows out of the hippocampus (the memory region) and into the
cortex. He thinks the brain then distributes the new information into appropriate networks and categories. Inside the brain,
proteins strengthen the connections between nerve cells consolidating the new skills learned the day before. Then later, during
REM, the brain re-enacts the lessons from the previous day and solidifies the newly-made connections through the memory banks.
What these studies show is that learning a new task, whether
it is sports or music, will be greatly helped by getting a good night's sleep and that students' ability to remember things,
be it a lesson on geometry or the causes of the Second World War, is mediated by sleep.
The proposition that sleep aids the learning process is accepted
by many researchers. In a review of the Harvard studies, the late Chris Gilpin described the research as "the most believable
data ever collected that a specific memory function is associated with sleep." However, a recent study published in the November
2001 issue of the journal Science challenges that conclusion. After conducting a literature review, Jerome M. Siegel
of the UCLA Department of Psychiatry and Brain Research and the Center for Sleep Research, judged the evidence of a link between
REM sleep and learning to be "weak and contradictory." He pointed to inconsistent results from human and animal studies, and
argued that studies of humans who do not experience REM sleep (due to brain injuries or pharmacological reasons) do not show
memory problems. Siegel concludes, however, that although he does not believe that the existing literature points to a link
between REM sleep and memory consolidation, "just as nutritional status, ambient temperature, level of stress, blood oxygenation,
and other variables clearly affect the ability to learn, adequate sleep is vital for optimal performance in learning tasks."
Learning Good Sleep Habits
Putting good sleep habits into practice is particularly difficult
for teenagers. Not only do their own circadian rhythms fight against going to sleep early, but many teens don't have any control
over the time they wake up. Teens can do something to try to bring their internal body clock forward. Sleep experts say dimming
the lights at night and getting lots of daylight in the morning can help. Having a routine bedtime of 10 p.m., sleeping in
a cool environment and turning off music, the Internet, and televisions would help to reset the body clock. And though sleeping
in is a good thing, trying to get up after only an extra hour or two is a lot better than "binge-sleeping" on the weekends.
If a student is used to getting up at 6:30 a.m., they shouldn't sleep until noon on the weekend. That simply confuses their
bodies. And lots of sports helps, too -- better earlier in the day than late.
Sleep research not only points out the importance of sleep to
teenagers, but explodes some of the myths around sleep: principally the idea that people need less and less sleep as they
grow up. There are many factors in the lives of adolescents that elude their control. Sleep is one area where the lessons
are clear and the benefits of following them are quickly apparent.
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