[Editor's note: This article is from 2007. Please also see further information on BrainWeb]
Sections include: brain a work in progress, plasticity and critical periods, from first words to first book, the first 3 years: myth or mandate?, encouragement and enrichment, bold or bashful?, what neurological impairments reveal, helping children explore the world, chart of expected visual develeopment
In the first moments after birth, as you and your spouse cradle this new child and stare down with wonder (and some exhaustion), you are probably not thinking about brain development. If you are thinking about your baby’s head at all, it may be only to provide it with enough support, or to be careful to avoid touching the “soft spots” where the bones of the skull have not yet joined.
But your obstetrician is thinking about your child’s brain, and the tests he or she performs soon after the birth are designed in part to measure brain function. The standard Apgar evaluation provides preliminary information about yourbaby’s overall health and development. The doctor looks at skin color, breathing, pulse, reflexes, and muscle tone. This examination takes only a few minutes and is done mainly to identify newborns that might need special assistance in the nursery.
A few days later, your child will undergo a more thorough examination, known as the Neonatal Behavioral Assessment Scale (NBAS). This test takes 20 to 30 minutes and evaluates your baby’s physical health, reflexes, and overall well-being as he or she adjusts to life outside the womb. While your baby sleeps, your pediatrician will use a light, a rattle, and other stimuli to see whether the infant can tune out these external distractions. This provides insight into the functioning of your baby’s central nervous system. The pediatrician will also evaluate your baby’s reflexes. Stroke a newborn’s cheek, and he or she will turn toward the finger (hoping to find a breast). Slip the tip of your finger into a newborn’s mouth, and the baby will suck. Support the newborn’s body across the palm of your hand so that his or her feet touch something solid, and the baby will take one step and then another, displaying the “walking reflex”—a foreshadowing of his or her first steps. These abilities, though rough and immature, show just how much brain development has already taken place before birth.
Your Baby’s Brain: A Work in Progress
Most parents know they must cradle a baby’s head carefully. A newborn’s neck muscles are not yet able to support the weight of its head—and just look at the size of that head! It is by far the largest part of an infant’s body. At birth, your baby’s brain is already one fourth the weight of an adult’s, even though his or her whole body weighs less than a tenth of an adult’s. This is the marvelous result of the prenatal development, when billions of neurons form, axons grow, and synapses start to connect the neurons.
All of those cells and links are sometimes referred to as the brain’s “hard wiring.” But that phrase implies that your baby’s brain at birth is equivalent to a circuit board in a radio, ready to be plugged in and played. It might be wiser to compare a newborn’s brain to early roots in a spring garden. The environment, the human version of sun and rain, will play an important part in how your child’s brain actually grows and the unique talents and personality traits he or she develops.
You don’t have to be a neuroscientist to notice the amazing development that takes place after birth. The same child who was so helpless as a newborn will be babbling at six months, and walking and talking with abandon as a toddler. These developmental milestones are matched by growth of the brain as an organ. In the first year, your baby’s brain triples in weight. By the end of the second, your toddler’s brain weighs three quarters that of an adult’s. The brain’s activity increases with its weight. The metabolism of a baby’s brain, as measured by how much blood sugar it uses, builds steadily from birth until the age of 3. At that point, your child’s brain is more than twice as active as yours, and it will remain so until he or she reaches puberty.
All that internal energy and growth is matched by the toddler’s external activities: exploring the world, reaching out for objects, gurgling and practicing sounds (the building blocks of language). And elements of your baby’s personality will begin to emerge sooner than you think. Some toddlers are shy, others bold. Some are rambunctious, others quiet. Some are easily soothed, others hard to calm down. (See more on these variables of temperament.)
So what’s going on? Although new cells are born in the rest of your baby’s body every day, the brain adds comparatively few cells after birth. Instead, the existing neurons grow larger and more powerful, sprouting axons and dendrites and connecting with neighbors. Some researchers have compared this blooming to the growth of a tree: branches emanate from the trunk of a cell’s body and reach out all around. These connecting branches account for the brain’s growth. And the synaptic connections enhance the brain’s computing power, its ability to accept sensory input from the outside world and make sense of it. Perhaps not surprisingly, synaptic growth is most significant during your baby’s first few years of life—when he or she is taking in all sorts of new input and acquiring new skills. By the time your child turns 3, each neuron has formed as many as 10,000 connections, making a total of about a quadrillion (1,000,000,000,000,000) throughout the brain. (That’s double the number of connections in your own brain.) Synapse formation slows after the toddler years, but continues throughout childhood and into adolescence, finally reaching adult levels when your child is anywhere from 15 to 18 years old.
Meanwhile, the process of myelination, which also began before birth, continues throughout childhood. Myelin not only protects the growing nerves, it helps them communicate better. The brain undertakes this task in stages. Those neural networks involved in early life skills (such as sucking and swallowing) are myelinated during pregnancy. The prefrontal cortex, the part of the brain involved in higher forms of learning, may not be completely myelinated until your child is 10.
But the first few years of life are not only about growth. This is also a time of selection. As your baby begins to see better, to explore his or her environment, and to interact with adults, the neurons in his or her brain transmit signals to each other. The neural networks that are used grow stronger; those that are not wither away, just as unused brain cells started dying in the last weeks before birth. This process is known as pruning. It is similar to the way a tree is pruned of excess or dead branches but is much more extensive. The death and removal of excess brain cells and connections truly sculpts a person’s brain. Growth and pruning continue throughout our lives, but the relative balance of the processes changes. Until your baby is 3, growth far outpaces pruning. From then until the age of 10, the formation of new connections is balanced by the elimination of unused ones. When your child reaches puberty, the balance finally shifts and the pruning of connections exceeds the formation of new ones.
Plasticity and Critical Periods
This whole process of synaptic formation and subsequent pruning helps explain the plasticity that is central to understanding the brain. Once your baby is born, his or her brain develops partly because of genetic instructions (nature) and partly because of exposure to the outside world (nurture). Experiences help determine which synapses grow stronger and which are pruned. Sometimes certain experiences are even necessary to “turn on” genes and unlock their natural coding. This interplay seems to be lifelong. Even the brain of an adult can continue to rewire itself and make connections after exposure to new situations. The result of all this is that the brain is custom-designed to function in its owner’s environment. In this way, the brain differs from the heart, lungs, and other organs, which follow a more standard and predictable developmental process.
We do not entirely understand why activating neural networks ensures their survival. It may be similar to the case of a muscle, which becomes stronger the more it is used. External stimuli send electrical impulses racing from one part of the brain to another. The more that a particular brain network is activated, the stronger the signal becomes. At some point, the signal becomes so strong that it triggers a resiliency in the network, so that these connections cannot be pruned away.
And timing may be everything. Neuroscientists believe there are “critical periods” for development, when a particular network of neurons and their connections are best made and strengthened. According to this theory, the brain overproduces synapses to ensure that it will be able to capture important experiences in relatively narrow time frames. Once the experience occurs, certain networks of synapses have been activated and become stronger. Those not used are pruned. Different parts of the brain go through critical periods at different times, depending on the skills needed.
One dramatic example is how your child learns to see. Look your newborn in the eyes, and he or she might look puzzled, as if coming out of a deep sleep. Both eyes and brain have to develop more before your baby will be able to see in the way that adults do. At first, babies can focus only on objects 8 to 15 inches (20–40 cm) away, and may go cross-eyed when trying to follow motion. By the time your baby is six months old, he or she is able to track all sorts of movements and focus on objects several feet away. As his or her first birthday approaches, your baby can see even small toys located across a room. Not until the second birthday, however, does a child’s vision reach mature levels.
All of this is the result of the interplay between genes and environment. Genes contain instructions for how to organize cells initially in the visual cortex, but these “ocular dominance columns” become functional and sophisticated only when a child begins to use his or her eyes to take in the outside world. Researchers who kept a kitten’s eye shut for several months after birth found that the cat was never able to see from that eye. Anatomically, the eye was fine, but the nerve pathway into the cortex had not developed because no sensory input was available. There have been similar findings about humans, though not because of deliberate experiments. At one time, the standard treatment for amblyopia (a form of crossed eyes) in newborns was to cover one eye with a patch until the muscles that controlled it had developed enough to be operated on; often, the eye was covered for so long that its nerve pathway never developed and it became useless.
Researchers believe that the same “use it or lose it” principle applies to other aspects of brain development—everything from hearing and moving to thinking and feeling. But just how the environment interacts with the underlying network of brain cells and connections is not well understood. Researchers have studied the phenomenon of critical periods most in the visual cortex. The issues get murkier when it comes to other types of learning.
For that reason, many neurologists and educators prefer to talk about “prime times” for learning and development. According to this theory, we can learn most skills any time in life, but they come most easily during particular periods. In some cases, these prime times can extend for years. So if your child is developing normally, there will be plenty of opportunity for growth; should a problem develop, there is usually time to fix it. An example of this is language development.
From First Words to First Book
At six months, babies may gurgle and babble. At nine months, they have progressed to “dada” or “mama.” By the time they are a year old, they may voice those sounds when they see their parents, connecting sounds and meanings to make actual words. Language is a skill woven from many threads: hearing sounds, mimicking them, speaking words, learning their meanings, stringing them together into sentences. Some aspects of language seem to be innate to us as humans, but most we have to learn. Mastering one set of skills leads to the next. And when language does not develop normally, the fault may lie in a problem with any one of the basic skills involved.
Long before a baby learns to speak, he or she is literally learning to listen, at least in a very basic way: distinguishing the various sounds of speech that add up to words and sentences. Between the ages of six months and a year, your baby is primed to be multilingual. Infants can distinguish the basic sounds used in every language, such as the consonants used in Thai but not in English. But consistent exposure to only one language, especially from hearing their parents and other family members, makes infants’ brains focus on the sounds that are meaningful in that language. By his or her first birthday, a baby who hears only English can no longer distinguish among those Thai consonants, because their subtle differences have no meaning in English. And a baby who hears only Chinese does not notice a difference between the syllables “ra” and “re,” which are not used in Chinese.
The next step, from distinguishing sounds to actually speaking, takes place gradually. According to one leading theory of language (but not the only one), when your baby hears you say something, signals received in his or her auditory cortex are then relayed to Wernicke’s area, the part of the brain that recognizes words. As your child starts to talk, he or she activates several areas of the brain in rapid succession. The basic components of the word form in Wenicke’s area, which then sends signals to an adjacent structure known as Broca’s area, which calculates the lip, tongue, and throat movements necessary for utterance and then signals the motor cortex to alert the required muscles.
Reading is a more advanced language skill, with a more complex neural pathway. When your child learns to read, his or her eyes send signals first to the visual cortex, then to an area known as the angular gyrus, where the words on the page are associated with sounds your child heard when the word was spoken. Those sounds, in turn, are communicated to Wernicke’s area, where the word is understood as if it had been spoken. Writing is a further skill, requiring the brain to send the right instructions to the child’s writing hand (or typing fingers).
In most children, this progression from hearing to speaking to reading and finally to writing goes without a hitch. And when something goes wrong, the brain is amazingly plastic. Some infants have had to undergo surgery to remove the left hemisphere of their brain because of spreading tumors. This hemisphere typically controls language, yet these children usually develop normal speaking and reading skills. The brain merely rewires this ability into the right hemisphere.
The First Three Years: Myth or Mandate?
Given all this emphasis on critical periods and prime times for learning, parents can feel awfully pressured. If you are not already concerned about what you should or should not be doing for your child, pick up a book or magazine on parenting; you will become a worrywart in no time. Today the popular media seems to emphasize your baby’s first three years, as if everything that follows depends on what happens during this initial period. Should you turn off the Top 40 radio station and play Mozart instead? Take away the teddy bear and invest in flash cards? Or throw up your hands and feel like a failure because your child is already older than 3?
The first thing to do is relax. Most insight into brain development during the first three years has come from research into extreme deprivation and adversity. For instance, we know how important individual attention and contact are for infants from what happened to orphans housed in institutions without such nurturing care. Though their physical needs were provided for, these children never received sustained attention from particular caregivers. As a result, they suffered from high rates of mortality and other problems. We saw heartrending examples in the Romanian orphanages that did not have enough staff to care for the many infants they housed. After spending their first few years in these settings, some of these or phans were adopted by well-meaning American parents. But in spite of loving homes and supportive care, many continued to suffer developmental delays and behavioral problems.
Many researchers argue, however, that studies of deprivation and adversity of this sort cannot be worked backward into a model of healthy brain development. And they point out that even severely deprived children can be remarkably resilient. Some Romanian orphans, for instance, are doing well.
Furthermore, most experts agree on one point about early child development. In the first three years, the most important things parents can do is to establish a strong, nurturing relationship with their baby. This primary attachment creates the groundwork for self-confidence, the ability to learn new things, and the capacity for getting along with other people. Building a healthy relationship means picking your baby up, cuddling, responding to his or her cries. It means playing games, singing nursery rhymes, and reading aloud at bedtime. These seemingly innocuous activities, which many parents do without prompting, provide sensory input (sights, sounds, touch) that stimulate the young neurons and connections in your baby’s brain. This is an important form of learning.
Sadly, if adults ignore a baby, or do not respond to his or her needs, that child will later have trouble forming attachments or empathizing with others. And the care has to be consistent. If it is not, the child may become anxious and clingy later on, almost as if he or she has decided the world is an unstable place.
Physically, all of this has to do with hormone levels in the child’s brain, which in turn affect his or her ability to regulate emotions. Although hormones are governed in part by genes, a child’s experience of interactions with his or her family helps fine-tune them. Specifically, attachment with a parent or primary caretaker helps modulate the levels of cortisol, the so-called stress hormone. When people experience stress, their cortisol levels rise to increase their heart and breathing rates (the “fight or flight” response). In the brain, high cortisol levels induce other chemical changes that can actually destroy neurons and unravel synaptic connections.
Researchers have found that babies who form a strong bond with a nurturing caregiver by their first birthday do not experience elevated cortisol levels in response to relatively low levels of stress. And when their cortisol levels do rise, these children are able to shut the response down faster and more efficiently than other children. On the other hand, children who experienced trauma or abuse, or who did not form a secure attachment, suffer from chronic high cortisol levels. Those babies raised in Romanian orphanages had elevated cortisol levels, researchers found. Such children are often slower to learn, walk, and interact with others than children whose cortisol levels remain normal.
What researchers cannot answer yet, and perhaps will never be able to say for sure, is exactly how much supportive care is necessary to rear an emotionally well-balanced child. Every parent occasionally loses his or her temper with a toddler (or teenager), or doesn’t feel up to playing at the end of a long day at work. And probably that is fine; it is long-term care rather than isolated instances that seems to matter. And much remains unknown. The mechanics of brain building in childhood are not understood as well as the right ingredients. It is as if parents receive a recipe that states only approximate measurements, temperatures, and cooking times. Following those directions can usually produce a good dish, sometimes an exquisite one, and sometimes one that needs a little help.
Encouragement and Enrichment
Your child’s brain matures in stages, as you can see in the gradual building of skills. Take walking, for instance. Few moments are as exciting as a baby’s first steps. You may view this moment as a whole new stage in your child’s development (and of course it is), but it is also the end of a long developmental journey deep within his or her brain.
Newborns’ movements have a jerky, spastic quality to them. But by the second or third month, your baby will be grasping objects and may seem more in control of other movements. As the months pass, infants can lift their heads and look around when placed on their stomachs. They will kick and rock and finally learn to sit up. They will learn to crawl, then to “cruise” by holding on to furniture and taking steps. Some babies prefer to scoot along the floor instead of crawling, and some stand up later than others (especially those in large, busy families). Almost all children pass through these stages as part of our natural human urge to reach further and move under our own power. And finally the big day arrives: your child takes those first wobbly but unsupported steps.
Your baby’s brain has been building toward this moment for a while. Those months of learning to sit up and crawl have helped build synaptic connections. Circuits have linked the visual cortex and motor cortex, helping your baby assess space and move within it. Muscle strength and control have improved, as has balance. The basal ganglia and the cerebellum are also involved, relaying messages back and forth. Toddlers use their legs to walk, but they also rely on their brains.
Higher-level skills also appear to develop in stages. Memory first emerges as a very simple function involving only the hippocampus, the part of the brain that receives and organizes new information. Infants as young as two months can recognize when they see something new, as shown by how long they stare at it. A child’s ability to consciously recall information at will does not begin to develop until his or her first birthday, however, and this system must mature during the next few years. One reason that people typically cannot remember much that happened to them before the age of 3 or 4 is that the parts of the brain necessary for recalling such memories are not “wired” then. The synaptic connections that link the hippocampus to the cerebral cortex have not yet been made. These connections become circuits as your child enters preschool. Meanwhile, other parts of the brain, notably the prefrontal cortex, are also developing. This enables a growing child both to understand why it is important to remember certain things and to develop tricks and strategies for recalling those things.
We also see how children’s minds develop in stages by looking at what they cannot do at different ages. Following the discoveries of psychologist Jean Piaget in the mid–twentieth century, development experts have recognized many ways in which children do not think like adults. For instance, preschoolers consistently believe that a tall glass can hold more than a shorter one, even if the shorter glass is significantly wider, and that there are more books and toys if they are spread all over the floor than if they are stacked away. Not until about school age do children realize that different people can have different knowledge of the world. And researchers are still debating when children can clearly sort out the real world from what they vividly imagine. Experience plays a role in moving children to the next level of cognitive development, but it seems that the brain has to be ready for that step as well. Parents and teachers can hurry a young child along only so much.
In movement, memory, and other functions, therefore, you will see your child develop preliminary skills, refine them, and then build on them to achieve more advanced skills. Inside your child’s brain at this time, neurons are firing signals, selected synaptic connections are growing stronger, and myelin is coating the nerves to make them more efficient. What educators see is potential: the more your child uses his or her brain, the more it grows. How can you facilitate this process? You can enrich your child’s environment and encourage him or her to explore it (even if that results in a few mistakes).
Researchers have seen the importance of enrichment clearly in rats’ brains. Rats who live in an “enriched” environment (full of toys and other rats) are better able to navigate mazes than rats raised in more austere environments. Furthermore, autopsies show that the enriched rats develop more synapses in the parts of their brains that control memory and vision. Intriguing research on people shows a similar pattern: learning particular skills changes the brain. One often-cited study of violinists found that the part of their somatosensory cortex devoted to controlling left-hand movement is larger than the area that governs their right hands. This is significant because violinists use the fingers of the left hand on the fingerboard which requires more motor control than their right hand needs to hold the bow. Furthermore, the change was largest in musicians who had begun taking lessons before the age of 10, suggesting that parts of the young brain literally grow with experience.
Bold or Bashful?
One toddler cowers and cries at the sight of a birthday clown; another rushes up and hugs the entertainer’s leg. What has created such a difference? Like cognitive skills, your child’s temperament is partly inborn and partly modified or enhanced based on interactions with parents, siblings, peers, and teachers.
Jerome Kagan’s work on shyness suggests that temperament is influenced by the amygdala, a small, almond-shaped area in the brain that functions almost like a relay station. The amygdala receives all sorts of sensory input about sights, sounds, tastes, and so on. It communicates that news to other parts of the brain involved in thought, emotional reactions, and behavior. The amygdala is also the part of the brain involved in the fight or flight response. When a child becomes frightened, the amygdala alerts the hypothalamus, which in turn triggers the release of cortisol. The hypothalamus also activates the sympathetic nervous system, causing a rise in heart rate, breathing rate, and temperature.
Kagan theorizes that some infants are born with amygdalas that are highly reactive, triggering a stress reaction in response to even a moderate stimulus. These infants will tend to be shy. Others, born with amygdalas that are not as reactive, will be less inhibited. He began testing babies before they were even born. Three weeks before a mother’s expected due date, Kagan measured the heart rate of the fetus. Then he asked the mothers to return with their babies at four months old, when his team exposed the babies to new experiences, such as a bright mobile or an unfamiliar voice, and monitored their heart rates. The researchers watched for the babies to smile and gurgle to signify comfort, or to flex their limbs and arch their backs to signify distress. The children were studied again at fourteen months, twenty-one months, and 41⁄2 years old.
Kagan and his colleagues found that children who tended to react with fear to new situations when they were four months old were more likely to by shy when they got older. The babies who were less fearful tended to develop into outgoing children. Interestingly, whether an infant would show a fearful reaction could be predicted, with a high degree of accuracy, by its heart rate in the womb. Infants who were low reactive tended to have fetal heart rates lower than 140 beats per minute; those who were highly reactive tended to have heart rates over that level.
So is biology destiny? Not necessarily. Kagan’s work also showed that only one in ten of the children who were highly reactive at four months turned out to be extremely shy by the time they were 41⁄2. Although the inborn tendency remained, most children were able to modify or overcome it with the encouragement of their parents and the accumulation of positive experiences. Few became as outgoing as the low-reactive infants, though. For most people, it seems, an inborn temperament remains a tendency for life.
Further evidence for the impact of environment appears in the way boys and girls start to behave differently by the age of 2. By that point, most of the shy children are girls, while most of the outgoing children are boys. Yet at four months, there were no differences between the sexes. Kagan theorizes that parents try harder to encourage their sons to overcome initial timidity, guidance then reinforced by a culture that expects boys to be bold. Other studies have shown that when adults play with an infant they have not met before, they consistently pick different toys depending on whether they believe the baby is a girl or a boy. It seems clear that we often place different expectations on boys and girls well before they turn 2, so it should not be surprising if different behaviors and even different thought processes result.
What Neurological Impairments Reveal
Many parents worry about what can go wrong in brain development. Fortunately, most children grow up in the normal range. And when something does go seriously wrong, it is usually beyond a parent’s or child’s control. In fact, one of the biggest contributions of brain imaging studies has been to show that the most difficult mental disorders are connected to abnormal chemistry in the brain, not to anything that parents or children have done.
Take autism, for example. Children with this developmental disorder withdraw from the world and are not able to communicate well or build relationships with other people. The underlying problem seems to be that autistic children do not know how to gauge and interpret other people’s expressions. Yet at the same time, people with autism may be extremely skilled and talented in other ways.
As late as the 1960s, psychiatrists thought autism resulted from cold, unemotional parents. Although that theory has been soundly rejected, the cause of the disorder remains unknown. Evidence now points to several possible culprits: abnormal genes, some sort of virus, or environmental poisons. Whatever the cause, an autistic brain functions differently from a healthy one. Imaging studies show that when someone with autism looks at another person’s face, the inferior temporal gyrus lights up; this part of the brain usually reacts only to inanimate objects, like blocks and trees. Cells in an autistic person’s limbic circuits, the brain circuits that control emotions, are not as well developed as they are in healthy people. Other research has revealed that subtle differences in brain chemistry may be present at birth.
Behavioral interventions to treat autism have shown promise, so both physicians and families are eager to find ways to diagnose the condition as early as possible. Children who develop the disorder can appear perfectly normal until they are toddlers, but then parents perceive their behavior changing: the child may resist being held, stop talking, and avoid making eye contact. Some subtle signs may even show up before a child’s first birthday: researchers who have analyzed home videos of autistic children in their first year have detected subtle abnormalities in their eye contact, gestures, and responsiveness to their names. For now, the American Academy of Neurology recommends consulting a pediatrician if your child has not babbled, pointed, or gestured at something by twelve months; has not spoken a single word by sixteen months or a two-word phrase by twenty-four months; or has shown any loss of verbal or social skills. These signs could mean anything from a hearing problem to a developmental disorder like autism. There are several types of screening tests to help you determine the possible problem and the best way to help your child develop.
Like autism, attention deficit/hyperactivity disorder (ADHD) was once thought to be a behavioral problem, not a biological one. Children with this disorder, fidgety and less apt to pay attention, were once regarded as willfully acting out. But researchers at McLean Hospital in Massachusetts have used functional MRI to find evidence of differences between the brains of healthy children and at least some of those with ADHD—specifically, reduced blood flow to the putamen, a part of the brain involved in movement and some components of attention. While these findings have yet to be confirmed and explored, most researchers now believe there is at least some biological basis for ADHD. It is still not clear why the condition develops in the first place, or what the best treatments for it are.
Sometimes we know the source of a brain impairment but see its effects only years later. Studies of children who suffered damage to the prefrontal cortex before they were sixteen months old, because of either surgery or an accident, show that they can grow up with a normal ability to learn but may lack certain social skills and moral reasoning. This implies that even social behavior, which most of us treat as entirely a product of the right sort of nurturing, may in fact be partly due to “nature,” or biological in origin.
But parents or other caretakers can still be to blame. Neglect and abuse can have devastating effects on children’s brains. Using brain imaging techniques and other tests, McLean Hospital researchers recently identified four distinct types of brain abnormalities in adults who were abused or neglected as children. These include electrical disturbances in the limbic region (sometimes referred to as the emotional brain); arrested development of the left hemisphere; reduced size of the corpus callosum, which links the hemispheres; and increased activity in the cerebellar vermis, which is involved in emotion, attention, and regulation of the limbic structures. The researchers theorize that people with such irregularities have been “hard-wired” to survive in a hostile world and suggest (though the evidence is less clear) that such damage may lead to the development of anxiety disorders, ADHD, and depression in adulthood.
Other studies of physically and sexually abused children show that about a third of themgo on to develop post-traumatic stress disorder. Symptoms of this disorder include disruptions in sleep, inability to concentrate, and recurring nightmares and are thought to be related to underlying changes in the brain. What is not clear is whether the damage is caused by particular traumatic episodes of abuse or by long-running deprivation or stress in the child’s home.
Helping Children Explore the World
The first day of school is a big step in your child’s life—and in yours. Even if your child was in day care, the transition to school is a significant, life-changing milestone. As your child progresses from preschool to kindergarten to grade school, you will notice his or her individual talents emerge and bloom. Your child’s crayon drawings may reveal the skills of a budding artist. Or an early facility with numbers may hint at a future career as an engineer or mathematician. At the same time, your child is developing in other important ways: making friends, playing team sports, and joining clubs and other after-school activities. This can be a bittersweet time for parents, as they proudly watch their babies become increasingly independent individuals. It can also be stressful; many parents worry about whether they should be doing more to help their children grow and mature.
Neuroscientists point to several signs that a child’s brain is especially primed for learning in the years between toddlerhood and puberty. Axons and dendrites are plentiful, creating a synaptic net that can capture many new experiences. Brain metabolism, as measured by blood sugar consumption, remains high. So does a healthy child’s energy. And while it is possible to learn new skills at any age, many researchers believe some are easiest to learn between the ages of 6 and 12. One dramatic example is language: children sometimes seem like sponges soaking up new words, both in the family’s primary language and in others they regularly hear. Not surprisingly, studies show it is easier for people to learn second languages before the age of 10 than after.
For most other skills, however, the guidelines are less clear-cut, and we must always recall that learning continues throughout life. Harvard educator Kurt Fischer believes that learning does not progress in a strict linear sequence (which he likens to rungs on a ladder), but instead flourishes as a result of growth cycles in which a child acquires preliminary skills and then uses them to build new capacities. Fischer has identified several growth cycles, involving everything from basic reflexes to abstract thinking, between birth and the age of 30. As a parent, it is also important for you to remember that each child is unique and will develop at his or her own pace.
So how can parents best help their children meet the challenges of the school years? Perhaps their most useful role is to continue to provide a warm, loving, supportive, and consistent environment. At times, your children need help with homework or special tutoring, but they always need to know you love them. Don’t worry if you’re a klutz at sports and can’t train your child into becoming the next Tiger Woods or Venus Williams. That’s a coach’s job. As parents, your job is to show your pride when your child plays hard and plays well. Another important part of the school years is learning to work with others; though children build these relationships mostly on their own, they start from their foundation of emotional support at home. There are many ways you can provide your school-age child with an enriched environment, but in order to explore any new activity, he or she needs to feel secure.
Challenge your child with new opportunities, but don’t overdo it. Many well-intentioned parents overstimulate their children and miss subtle and not-so-subtle signs that the kids just aren’t interested or have had too much. Exposing children to Mozart may make them more receptive to classical music. But it does not guarantee that they will grow into musical prodigies or even like such music later on. Sometimes it is more healthy to let a child discover his or her own interests. Educators and psychologists agree that when children enjoy an activity, they become more attentive and more motivated to improve. Although all parents want their children to become well-rounded, it is also important to give your child the time and freedom to pursue activities on his or her own. This builds self-confidence, discipline, and motivation, which are all important as your child approaches the teen years. And a child needs opportunities to explore, directed by his or her own brain.
Pay attention to your growing child’s physical health as well, because that affects his or her brain. Establishing healthy eating habits in childhood is one of the best ways for people to avoid becoming overweight, which could lead to diabetes, hypertension, and eventually an increased risk of stroke. Immunizations and regular checkups at the pediatrician can head off some neurological problems. Requiring your child to wear a helmet while bicycling, skateboarding, or doing similar activities, and to wear a seat belt while riding in a car, can greatly reduce his or her chance of suffering a serious head injury. School-age children have the mobility and the energy to explore their worlds, but they don’t always have the experience to know what is unsafe.
Finally, if you can, relax and enjoy childhood while it lasts. Puberty and the turbulent teen years follow soon enough.
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EXPECTED VISUAL PERFORMANCES
BIRTH TO 6 WEEKS OF AGE:
■ Stares at surroundings when awake
■ Momentarily holds gaze on bright light or bright object
■ Blinks at camera flash
■ Eyes and head move together
■ One eye may seem turned in at times
8 WEEKS TO 24 WEEKS:
■ Eyes begin to move more widely with less head movement
■ Eyes begin to follow moving objects or people (8–12 weeks)
■ Watches parents’ face when being talked to (10–12 weeks)
■ Begins to watch own hands (12–16 weeks)
■ Eyes move in active inspection of surroundings (18–20 weeks)
■ While sitting, looks at hands, food, bottle (18–24 weeks)
■ Now looking for, and watching, more distant objects (20–28 weeks)
30 WEEKS TO 48 WEEKS:
■ May turn eyes inward while inspecting hands or toy (28–32 weeks)
■ Eyes more mobile and move with little head movement (30–36 weeks)
■ Watches activities around him or her for longer periods of time (30–36 weeks)
■ Looks for toys he or she drops (32–38 weeks)
■ Visually inspects toys he or she can hold (38–40 weeks)
■ Creeps after favorite toy when seen (40–44 weeks)
■ Sweeps eyes around room to see what’s happening (44–48 weeks)
■ Visually responds to smiles and voice of others (40–48 weeks)
■ More and more visual inspection of objects and persons (46–52 weeks)
12 MONTHS TO 18 MONTHS:
■ Now using both hands and visually steering hand activity (12–14 months)
■ Visually interested in simple pictures (14–16 months)
■ Often holds objects very close to eyes to inspect (14–18 months)
■ Points to objects or people using words “look” and “see” (14–18 months)
■ Looks for and identifies pictures in books (16–18 months)
24 MONTHS TO 36 MONTHS:
■ Occasionally visually inspects without needing to touch (20–24 months)
■ Smiles, facial brightening when views favorite objects and people (20–24 months)
■ Likes to watch movement of wheels, egg beater, etc. (24–28 months)
■ Watches own hand while scribbling (26–30 months)
■ Visually explores and steers own walking and climbing (30–36 months)
■ Watches and imitates other children (30–36 months)
■ Can now begin to keep coloring on the paper (34–38 months)
■ “Reads” pictures in books (34–38 months)
40 MONTHS TO 48 MONTHS:
■ Brings head and eyes close to page of book while inspecting (40–44 months)
■ Draws and names circle and cross on paper (40–44 months)
■ Can close eyes on request, and may be able to wink one eye (46–50 months)
4 YEARS TO 5 YEARS:
■ Uses eyes and hands together well and with increasing skill
■ Moves and rolls eyes in an expressive way
■ Draws and names pictures
■ Colors within lines
■ Cuts and pastes quite well on simple pictures
■ Copies simple forms and some letters
■ Can place small objects in small openings
■ Visually alert and observant of surroundings
■ Tells about places, objects, or people seen elsewhere
■ Shows increasing visual interest in new objects and places
REMEMBER: All the age ranges given above are approximate. Lags of a week or so are not unusual, but any definite developmental
delay or nonperformance should be given every necessary attention. The performances listed above are important. All are preparatory
to school readiness and are visual skills that are essential to lifetime activities.
Excerpted from: A Reference Guide for Preschool Children’s Vision Development © Optometric Extension Program, 1995
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