You may feel confident that you can outsmart your three-year old, but when it comes to brainpower, he’s probably got you beat. The metabolic energy consumed by a child’s brain is 225 percent that of an adult. Does that mean your child is far more intelligent? Probably not--but it does indicate that he’s thinking and processing information at a much greater rate. And at this tender young age, he holds an incredible strength--his immense capacity for learning.
By Amy DiCresce
"This is clearly during the terrible 2s," said Harry Chugani, MD, as he points to a brain scan illustrating outstanding surges of energy consumption in the brain of a young child. "The biochemical processes are especially hard at work and the brain is a virtual sponge at this stage of development," says Dr. Chugani. "I’m not sure if it makes parents feel better or worse, but it does show the incredible capabilities children have very early in life."
Dr. Chugani has captured the interest of parents, educators and medical experts across the country with his research on childhood development and the "turning on" of the brain. As professor of pediatrics, neurology and radiology at the Wayne State University School of Medicine, and director of the Positron Emission Tomography Center at Children’s Hospital of Michigan, he and his colleagues have observed patterns of complex brain maturation, which shape a child’s learning capacity and behavior at very precise times.
Using Positron Emission Tomography (PET), Dr. Chugani is able to measure the amount of glucose and oxygen consumption in various parts of the brain. More glucose indicates more activity; and more activity is proof of learning and thinking processes at work. Furthermore, a direct link has been drawn between the focal area of energy concentration and the development of certain behaviors.
For example, in newborn babies, brain activity is primarily based in subcortical regions--the location responsible for intrinsic responses such as respiration, heart rate and grasp reflexes. As the child matures and phylogenetically newer regions of the brain become functionally active, the child achieves greater behavioral complexity. By three months of age, glucose consumption has risen in the parietal and temporal cortex, corresponding to increased coordination and the child’s more fluid and intentional reaching movements. By eight months, much of the frontal cortex is activated, which coincides with a child’s higher cognitive function and his ability to be more aware of his surroundings.
"The relationship between an expanded repertoire of behaviors and increased energy consumption in certain areas of the brain is not coincidental," said Dr. Chugani. "Children undergo a complex process of brain development very early in life. Much of this is a natural biological progression, but Mother Nature didn’t think it was advisable for genetic composition alone to dictate brain wiring. At some point, very early in childhood, the automatic responses subside and the rest is left up to the parents or caretakers. That’s when the fun begins."
A child’s brain begins as a chaotic pool of unconnected neurons waiting to be stimulated, directed and wired in some logical pattern. This complex wiring creates an excessive number of connections, causing the brain to rapidly overdevelop between the ages of two and 10. Although trillions and trillions of neurons are connected during this burst of discovery, more than half of the excessive connections will eventually be eliminated. The trick, according to Dr. Chugani, is to keep desired connections alive and permanent to allow for efficient processing of a variety of functions.
During the first decade of life, the cerebral cortex undergoes a dramatic curve in energy consumption. Metabolic rates in the brain rapidly increase beginning at birth and begin to reach adult values around age two. At age three, a child’s metabolic brain energy far exceeds adult levels, and by age four, a "plateau" is reached which lasts until about age nine. This plateau is the result of hyperconnectivity, where cortical neurons have formed excessive connections, which are later either preserved or selectively eliminated depending upon exposures and stimuli. Around age 10, plasticity of the brain begins a gradual decline until 16 or 18, at which point, the levels of glucose utilization have reached adult values.
Because the regions of the brain develop systematically, there are critical windows of opportunity for learning. Different regions become more malleable during particular phases. "Our brains are particularly open to certain stimulations at certain times," said Dr. Chugani. "Once that time is up, you can never recapture that unique ability." This concept was proven in the 70s with experiments showing that cats can be blinded simply by covering their eyes during critical periods of infancy. If the connections are impaired during the windows of opportunity, the brain will never be able to perform the task, even when the eyes are reopened.
The same logic applies to humans. So if your little girl wants to play a musical instrument, she shouldn’t wait until age 20 when the cortex is already developed. She should begin at age five when her cortex is being wired specifically for such skills. The connections then become part of the brain’s formation. Dr. Chugani explains it this way. If a child has done something many times before, it becomes easier, not just physically but biologically, too. The pathway in the brain becomes very clearly drawn or wired over time. So if a child learns a second language or plays a musical instrument very early, the connections for that task are very clear and unobstructed. If the child has never encountered a situation before, the brain has to try several different pathways, and may be re-routed several times before making the appropriate connection.
When Carla, Dr. Chugani’s 12-year-old daughter, took piano lessons a few years ago, her father joined her in the musical pursuit. "Carla picked right up on it," he said. "But I had a hard time making my fingers move correctly. It’s not that I will never learn to play the piano, but it will never come naturally for me. In a child, it is part of their brain architecture." On the other hand, Dr. Chugani played the guitar as a youngster, and when he attempted that, it came right back to him. People don’t stop learning as they mature, but they do lose some natural advantages.
"It’s a balance between nature and nurture," Dr. Chugani said. "All kids who take music lessons won’t be great musicians. Likewise, we can’t teach kids to throw a ball and automatically expect them to become great athletes. But if a child isn’t exposed to those experiences early in life, the natural potential is lost. The related neuron connections are eventually shut down and destroyed, so you’ll never know your full potential."
Dr. Chugani also stresses the importance of repeated and reinforced learning. Research suggests that crash courses in a second language are much less effective than continuous learning over four or five years. It doesn’t do much good to enroll a child in a French class for one semester, because the brain benefits from repeated exposures, not intense isolated hits. This same reasoning explains how children become wired for positive or negative behaviors. They learn what is reinforced throughout their childhood.
Why do all members of some families seem to continually explode or overreact to simple situations? A child’s automatic response mechanisms are learned through collected past experiences over a lasting period, so if you are raised in a hostile environment with parents who often yell or exhibit violent behaviors, you will probably become "hard-wired" for hostility. The brain doesn’t screen out negative behaviors. This is just one reason Dr. Chugani is opposed to television violence. "It becomes a passively learned behavior," he said. "You learn what you see--and again the brain doesn’t differentiate between good and bad." All exposures are registered and stored until they become reinforced or contradicted by others.
Parents, teachers and family members have a crucial role in helping children foster dynamic thought processes. "It’s important to engage children in discussion, problem-solving and reasoning, even at the simplest levels," said Dr. Chugani. "There are small things you can do every day to encourage learning. The other day I took a walk with my three-year-old son, Ryan, and there was a cracked sidewalk with tree roots jutting up between the concrete slabs. I asked my son why that happened, and he explained how roots grow out from the tree and are strong enough to break through the ground. You don’t have to buy special workbooks or be enrolled in the most innovative school systems to facilitate learning--you just have to encourage kids to think analytically for themselves."
Although Dr. Chugani has used the results of Positron Emission Tomography to observe important patterns in brain development, that is not its clinical use. He first used PET technology to detect microscopic brain malformations in epileptic children with uncontrolled seizures; the discoveries about brain maturation were ancillary to the clinical diagnoses he was making. PET, which was developed at UCLA where Dr. Chugani was a faculty member, is the most precise camera used to study biological functions and chemical imaging of the brain and other organs. The non-invasive procedure is important because it measures metabolism, not structure (as detected by MRI or CT scans). For instance, an x-ray may detect a tumor, but PET can examine its chemistry to determine if it’s malignant. The presence of diseases and abnormalities can be detected and treated much earlier through diagnostic PET.
During a PET scan, the patient is injected with a chemical tracer labeled with positron-emitting isotopes, which go to certain areas of the brain. The positrons released collide with electrons in the brain, producing gamma rays which are emitted at a precise angle. The PET scanner determines the precise location of the gamma ray emission and gives a clear picture of the activity in that region. The physician can see the location of the metabolic process, or in Dr. Chugani’s patients, he can pinpoint the location of an epileptic seizure in a child’s brain.
After being recruited by medical centers including Mayo and Emory, Dr. Chugani came to Wayne State University/Children’s Hospital of Michigan in 1993 because it was the only place in the country with a PET scanner devoted to childhood illnesses and disorders. Dr. Chugani is very busy performing approximately four new scans each day, in addition to providing surgical options and other treatments. He is director of the pediatric epilepsy surgery program and as a pediatric neurologist, he works with surgeon Dr. Alexa Canady to define and remove the focus of epileptic seizures in the brain. Almost half of his patients are from outside Michigan because everybody is looking not only for the technology, but for the expertise in operating and interpreting the technology.
Dr. Chugani’s research into epileptic seizures has also demonstrated the brain’s incredible plasticity, or ability to reorganize. Children, unlike adults, can endure damage to large areas of the brain without major functional deficits. A young brain can reorganize or learn to compensate for missing areas, if it’s still in formation stages. For example, some children suffering from epileptic seizures may need an entire hemisphere of their brain removed, but they can still have a normal IQ, because their brains readjust and reorganize to function quite normally. If the window of opportunity remains open, the brain will work like new.
Currently, PET at Children’s Hospital is primarily used to help children suffering from uncontrolled seizures, but it has other uses too. Oncologists use PET to determine whether tumors are malignant; heart specialists analyze coronary artery disease in children by evaluating blood flow to damaged heart muscles; and a new probe is able to measure serotonin synthesis, which is abnormal in autistic patients. The options are not limited to children, however. Psychiatrists can determine brain activity in people suffering from dementia and schizophrenia; changes in brain metabolism may be a marker for Alzheimer’s disease; and metabolism rates in the kidneys can indicate various renal diseases. Any part of the body experiencing abnormal biochemical changes can be seen through PET.
For Dr. Chugani, however, the brain is still the most exciting part. He envisions a day when physicians will be able to map each region of the brain and label its most precise functions.
When the state of Connecticut lost a lawsuit against a student who felt she hadn’t learned anything from the public school system, they formed a commission on children and education. Dr. Chugani was a consultant to that commission, and he’s also involved in formal and informal advocacy groups for better educational systems. "Other states across the nation are watching too," said Dr. Chugani. "Childhood education is a big concern and people of all disciplines are coming together to make changes. We’re teaming up with doctors, educators and politicians to provide better options and opportunities for our kids."
Programs steering this new movement advocate teaching children at very young ages--two, three and four. Research has shown that intervention after age five has less measurable academic benefit. Developing basic skills early in life helps youngsters form the basis for more complex skills such as reading, writing and reasoning. As Dr. Chugani said, we shouldn’t be afraid to get our children started early, even in subjects that are seemingly difficult. It’s surprising what kids are capable of.
Dr. Chugani’s work has captured the attention of media reporters and medical experts around the world. His national media appearances include ABC’s Prime Time Live, an American Agenda Special Report with Peter Jennings, Good Morning America, the cover story in Newsweek magazine and several articles in The New York Times, just to name a few. With every opportunity, he continues to reinforce his message: Teach children more, earlier and better.
So what are the three or four essential things that all children should be exposed to? "Three or four aren’t nearly enough," said Dr. Chugani. "Kids need a whole world of exposures and stimuli. They need more and more all the time, and they need to ask why and how."
Smile at your infant--the brain will learn to reciprocate the behavior. Talk to children--the more words they hear, the faster they learn to speak. Play counting games--it helps develop math and logic skills. Let kids run and play--it forms efficient connections in the motor system and cerebellum, allowing them to move smoothly.
By simply changing when we learn, we can drastically change the quality of our learning.