Brain Development and the Art of Parenting
Message from the Health Officer: Research on brain development provides exciting evidence to support what we instinctively know - that early childhood is a crucial time to begin investing in children to ensure their optimal development and to provide an enriching environment that facilitates brain development. This policy brief teaches us that in the first three years of life, an infant’s brain is developing, and that experiences shape this development. An enriched environment, which includes day-to-day activities such as talking, playing, and looking at books, will facilitate development in the regions of the brain that control these functions. Conversely, severe deprivation and insecure attachment with the primary caregiver (usually the mother or father) can have a negative effect on brain development, particularly on the child’s ability to retain memories and therefore to learn.
Children learn well before they reach school, and early learning experiences actually shape the architecture of the brain. While learning can take place throughout life, the flexibility of the brain in the early, developing years provides an opportunity for enrichment that is probably unmatched at any other time. We must support our children during this early stage to take full advantage of this unique window of opportunity. To do this, we must invest in our communities by supporting education and learning opportunities, and programs that foster stable, well-functioning families.
Jonathan E. Fielding, MD, MPH
Director of Public Health and Health Officer Los Angeles County Department of Health Services
INTRODUCTION
In recent years, parents and policymakers have become increasingly interested in the potential role of positive early childhood experiences in promoting a child’s emotional and intellectual well-being. Much of this interest has been sparked by numerous articles in the popular press claiming that recent advances in brain research can give parents guidance about everything from buying toys to choosing a preschool. While this growing interest in early childhood and the impact of early life experience is unquestionably a good thing, it has also contributed to the spread of sometimes inaccurate and frequently misunderstood information about what conclusions can be drawn from our knowledge of brain development. This brief reviews the research about early childhood brain development in order to provide policymakers with some of the information they need to consider as they help parents create a healthy and stimulating environment in which their children can grow. The excitement about brain development in infancy and early childhood is well justified by the research, but caution must be exercised in drawing conclusions for parents and public policy at a time when the research and knowledge base is evolving rapidly (Cicchetti and Cannon, 1999).
The scientific community has called the years from 1990 to 2000 “the decade of the brain,?because it is during this period, building on the work of the preceding two decades, that our understanding of brain development increased exponentially. In this brief, we have attempted to identify key scientific principles that emerge from intensive efforts to unravel the cellular and physiologic basis for brain development in humans. As is the case in any field of scientific study, even these basic principles are open to challenges by new information. For example, in the past two years, articles in Science magazine and proceedings of the National Academy of Science, as reported on the front page of the New York Times, presented new findings suggesting that one piece of scientific orthodoxy ?that individuals are born with all the brain cells they ever have - may be incorrect. The articles describe a series of experiments demonstrating that, in fact, parts of the monkey cortex responsible for memory formation and consolidation (the hippocampus) may grow new brain cells on a daily basis. Thus, while we have provided a summary of our knowledge of brain development, readers should keep in mind that scientific investigation continually expands our understanding in new and sometimes unexpected directions.
WHAT DO WE KNOW ABOUT BRAIN DEVELOPMENT?
Like much of human development, the development of the human brain is the result of a complex interaction between nature and nurture, between the unique genetic code an individual inherits and his or her experience both before and after birth. Recent research in the fields of neurobiology and developmental psychology provides evidence of the specific processes involved in human brain development, particularly the process by which even the earliest experience affects brain development. Much of what we know about human brain development is derived from studies that involve extensive and invasive experimentation on rats, monkeys and other animals. These experiments enable researchers to directly observe brain development by measuring and comparing physiologic processes directly from the brains of animals reared under various conditions. Researchers use these direct measures of brain functioning to draw conclusions about the effect of various types of experiences on brain development.
Because it is not possible to directly measure the cellular processes involved in human brain development, scientists rely upon a number of reasonable assumptions about the extent to which animal and human brain development are similar. Since some animal and human psychological behaviors are similar, scientists can also make inferences about the neurobiological processes underlying these behaviors. For example, the new nerve cell connections that take place in the hippocampus of rats, tree shrews, primates, and humans during adult life can be inhibited by stressful social experiences (Bremner and Narayan, 1998; McEwen, 1998). Recent technological advances have improved the ability of neuroscientists to study human brain development and functioning directly through the use of noninvasive techniques such as electroencephalographic (EEG) recordings and functional magnetic resonance imaging (FMRI). These new technologies provide a non-invasive window to some of the physical processes that are observed in invasive animal studies. For example, a recent report in the Lancet medical journal presented information about how FMRI had been used to observe the activation of the temporal cortex in fetuses who were played nursery rhymes through earphones placed on their mothers? wombs, suggesting that the fetus’s brain is already processing information. As more direct observation of brain development in humans is performed using such techniques, our understanding of the process by which human brains form and function is bound to increase significantly, and correlative research from other animals will be confirmed. Already, five general findings have emerged from this growing body of knowledge. These findings have important implications for both parenting and public policy efforts to support brain development during early childhood.
A child’s brain is not mature at birth.
The newborn infant has approximately the same number of “neurons??or brain cells ?as an adult, yet only about 25% of his or her brain’s volume has developed (Blinkov and Glezer, 1968). Neither the connection between the infant’s neurons, nor the supporting cells that insulate them, are fully formed at birth. The infant’s brain cells are connected by approximately 50 trillions synapses. Over the ensuing years, brain volume will quadruple, while synaptic density will increase even more as the number of synapses grows ten fold by adulthood to approximately 500 trillion. Moreover, as these new cells grow and connections are established, each of the new cells is insulated by a lipid material called “myelin,?that promotes more rapid conduction of nerve impulses.
Even more important for brain development is the fact that in the first three years of life the young child’s brain forms double the numbers of synaptic connections (approximately 1000 trillion) that are ultimately present in the adult brain. These “extra?synaptic connections provide an important clue to how the brain is shaped by experience. Beginning at age 3 and continuing over the next decade or more, synapses are selectively eliminated so that by age 15, the number of synapses in the brain has decreased by about half and remains relatively stable throughout the rest of the individual’s life (Huttenlocher, 1984).
The process of selectively eliminating synapses is so essential to creating order in the human brain that some individuals with an overabundance of synapses have serious behavioral or cognitive disorders, as seen in the condition called Fragile-X Syndrome. Studies of monkeys have likewise indicated that cognitive ability reaches mature levels only after the selective elimination of synapses has been completed (Woo et al., 1997).
A child’s brain is changed by experiences.
The structure and function of a child’s brain is not only influenced by its genetic inheritance, but also by experience. While genes program certain types of nerve cell connections, experience also programs and reprograms nerve cell connections. Depending on the type of function, the relative influence of genetic versus experiential influences can differ. For example, brain centers that control breathing and heart rate are relatively hardwired at birth, whereas higher cortical functions that have to do with learning and memory are sculpted and modified by experiences. This newer understanding of brain behavior relationships yields a picture of the brain as a plastic and self organized organ in which the development and maintenance of nerve connections is based on experiential demands and not strictly predetermined (Gottlieb, Wahlsten and Lickliter, 1998).
Both the growth and elimination of synapses in the brain depends on an individual’s experiences. Experiences that stimulate activity in particular regions of the brain facilitate the growth of connections in those regions, so that synapses can be said to form in a “use-dependent?manner. Even before birth, the ongoing spontaneous firing of neurons in the immature brain is thought to stimulate the formation of synapses. For example, it has been hypothesized that neurons that happen to be triggered at the same time will connect to each other, so that cells that “fire together, wire together?Peen and Shatz, 1999). It has been suggested that the incidence of spontaneous neural activity supports a proportion of synapse formation, and is genetically controlled in order to ensure that an adequate number of connections are formed during gestation and very early in life, before much external stimuli is available. The connections that form from these spontaneous synaptic firings are not random, but they are relatively disorganized.
Nonetheless, even as these rudimentary connections are being made before birth, the brain is capable of learning. In one experiment done in Belfast, Northern Ireland, infants of mothers who had routinely watched a BBC soap opera during their pregnancy were found to respond specifically to theme music of that show a few days after birth (Hepper, 1996). Following birth, the brain continues to create spontaneous neural activity, but, increasingly over time, synapse formation is supported by the external stimuli the infant receives from the surroundings, such as the taste of warm milk, the feeling of a mother’s caress, or the sound of a father’s voice. The brain’s response to these external stimuli is known as “sensory-driven?neural activity. Synaptic firing leads neurons to form connections to other cells that have also been activated by sensory stimuli and experiences in their new world. Because neurons that are activated by a particular type of stimulus most likely have a role to play in receiving, processing and responding to it, and because cells that are activated in synchrony become connected, sensory-driven neural activity drives the circuitry in a young child’s brain toward increasing organization.
As is the case in much of recent neurobiology research, experiments with other animals have revealed a great deal about basic mechanisms. For example, the amount or type of stimulation provided by the environment has been found to have a measurable impact on the physical development of the rat brain. One now-classic study found that rats raised in enriched environments had 30% greater synaptic density in their cerebral cortexes than did rats confined to non-enriched environments (Black, Isaacs and Anderson, 1990. See also Diamond, 1990). The rats in the enriched environment had access to challenging situations such as mazes, as well as a variety of visual stimuli. The researchers concluded that the observed difference in synaptic density between the two groups of rats was a reflection of the difference in richness of experience, and that a more natural, stimulating environment allowed a rat’s brain to develop in a normal way.
In addition to fostering the growth of synapses between neurons, an individual’s experiences also determine which of the existing synapses will survive the process of selective elimination that begins around three. Again, the principle of use-dependence applies. Experiences that utilize the connections in particular regions of the brain ensure that those connections will survive, while connections that are not utilized will be lost. Evidence for this phenomenon also comes from well-known animal studies. Kittens deprived of visual stimulation in one eye for a short time early in life lost permanently the ability to see out of that eye. In this study, and similar ones, neuroscientists concluded that the region of the brain responsible for visual perception was never encouraged to grow and maintain connections to that eye because the eye was not used (Hubel and Wiesel, 1971). For the same reason, children less than 18 months of age whose cataracts are untreated can have a dramatic and permanent loss of visual activity in the untreated eye (Boothe, Dobson and Teller, 1985), and the duration of the time in which the eye is not used is directly related to potential visual acuity once the cataract is removed and vision is restored (Mitchell and Timney, 1984).
The fact that synapses grow and form connections on a use dependent basis is indicative of the fact that the human brain is fundamentally an adaptive organ, whose physical organization is shaped by the environment. In this sense, learning is the process by which the brain responds adaptively to the environment in which a child is raised. Therefore, learning includes much more than the verbal and cognitive skills that are the focus of the K through 12 classroom education.
It is also clear from available studies that extreme deprivation, such as the rats and kittens described above were subject to, can have serious consequences for brain development. However, these studies should not be interpreted to suggest that if parents provide their children with unusual types or excessive amounts of stimulation, that their children’s brains will develop more quickly or have greater intellectual capacity. At present, there is no empirical data to suggest that providing extra stimulation above what is normally expected by the developing brain has a beneficial effect in terms of brain growth or synaptic connections. This lack of evidence should not be interpreted as a lack of effect, but reflects the fact that, at present, non-invasive techniques have demonstrated that different kinds of input have different kinds of effects on the developing human brain. However, there are a number of studies by developmental psychologists that suggests that providing infants and young children with specific enriching experiences can boost their cognitive and behavioral functioning (Infant Health and Development Project, 1990 Ramey et al., 1992).
Our exploding knowledge about the brain has also revealed that the brain is not a large, undifferentiated computer with a single control processing unit. Rather, a better metaphor would be a collection of interactive and specialized processors (Cyander and Frost, 1999). The functions of each of these processing units depend on developmentally timed molecular and cellular events that must be programmed in the correct sequence to optimize the functioning of the system.
Therefore, not only does experience play an essential role in brain development, but the timing of certain experiences is important as well. In the first few years of life, individual regions of a child’s brain go through periods of time which neuroscientists call “critical periods.?During these periods the brain appears to be relatively more plastic, and therefore both amenable and vulnerable to the influence of experience. As the child ages, existing synapses in a particular region of the brain are thought to stabilize, suggesting that it may become more difficult to create new connections in that region. Therefore, neuroscientists suggest that the critical period of each developing region of the brain represents a window of opportunity during which specific experiences and stimuli are required in order to promote the usedependent synaptic growth described above (Cyander and Frost, 1999). Most of these studies documenting the existence and role of critical periods have focused on sensory processing (i.e., vision, hearing) in animals and on certain animal imprinting behaviors. In addition, there is growing evidence for critical and sensitive periods for other higher critical functions as well (Cyander and Frost, 1999: Cicchetti and Cannon, 1999).
However, it is important to emphasize that there is no single critical period of brain development in early childhood, or at any point in an individual’s life. Instead there are multiple critical periods. Different regions of the brain, each corresponding to a particular set of abilities or behaviors, become connected to the other regions at different times in a hierarchical fashion (Chugani, 1998). When a child is born, the brainstem, the “lowest?region of the brain responsible for basic functions such as heart rate and body temperature regulation, is immediately wired and stabilized because of its essential role in ensuring survival. Subsequently, other regions of the brain associated with child’s developing emotional and sensory motor capacities begin to develop a web of selectively maintained synapses, driven by the interplay of genetic and environmental influences. Because the various regions develop, organize and become fully functional at different times, specific kinds of experiences facilitate development in each region during that region’s critical period (Perry, 1997).
The development of language is one example of how critical periods influence brain development. The capacity to hear and produce all of the sounds, or phonemes, used in any human language is latent at birth.One study found that while both one-month-old American and Japanese infants were able to distinguish between the English sounds of L and R. the Japanese infants could not make that distinction a mere five months later (Kuhl, 1997). Because the potential capacity to distinguish and produce specific phonemes that are not present in a child’s native language gradually decreases as the child ages, adult native Japanese speakers find it extremely difficult to distinguish between these unfamiliar sounds. However, it has also been shown that adult Japanese speakers can learn to distinguish between L and R if they participate in a program specifically designed to teach them the difference - in effect, reprogramming their neural connections through additional experience (McClelland, 1999). Researchers have also identified a window for acquiring the sounds of a new language without an accent between ages 2 and 14 (Flege, J.E. et al., 1995).
Studies like those described above suggest that it is difficult, but not impossible, to acquire new language skills well into adulthood. For example, we all know from our own experience that it is possible to improve our vocabulary in our native language throughout our lives. Similarly, while it is unquestionably easier to learn to play a musical instrument during childhood, it is certainly possible for adults to learn to play with additional lessons and extra practice.
These examples indicated that critical periods apply to the development of certain abilities, but not others. The brain plasticity that occurs during critical periods ?enabling the development of abilities such as vision, hearing, and the capacity for language ?has been called “experience-expectant,?because it is responsive to stimuli that are so common in human life that they are practically guaranteed to be available (Greenough, 1987). Yet, because of experience-expectant development, when health problems such as cataracts occur during the critical period for the development of vision, or when chronic ear infections occur during the critical period for the development of hearing, the child may not develop normal sensory abilities. The critical timing issues associated with experience-expectant development of the brain are one of the most important reasons that children require early, prompt and timely access to health services when developmental problems are detected.
For other abilities ?such as the ability to learn a new language, to improve our native language vocabulary, or to learn a musical instrument ?the window of opportunity appears to remain open for a longer period of time if not throughout a person’s life. This type of brain plasticity has been called “experience dependent.? It is responsive to experiences that are not necessarily present in everyday life (Greenough, 1987), but that instead depend on an individual’s unique life circumstances. From an evolutionary standpoint, it is helpful for an individual to be able to acquire new abilities throughout life and remain amenable to the influence of unexpected opportunities to learn more.
From a policy perspective, many of the most important brain based capacities of children are not experience-expectant, but experience-dependent. For example, research suggests that literacy is a complex set of skills that can be encouraged by experiences that may not be available to everyone, such as being read to daily or being enrolled in early childhood education (Whitehurst and Lonigan, 1998). Thus, from a policy standpoint, the goal of early childhood brain development is not only to ensure that all children develop functional sensory and motor skills, but that they are exposed to the experiences and social interactions that are thought to encourage the underlying experience-dependent neural foundation upon which literacy can be built.
What do the last three decades of brain research tell us about what constitutes an appropriate experience at any given point in a child’s life? On the one hand, research suggest that there are serious and potentially irreversible consequences when animals are deprived of the kinds of stimulation they would have expected to receive under normal conditions. On the other hand, we know that mother cats do not go to unusual lengths to provide their offspring with visual stimulation. Rather, most kittens develop normal visual abilities from watching their brothers and sisters wrestle, or from chasing a mouse. Similarly, most rats will develop normal brains from running through sewers or fields in search of food while learning to steer clear of predators. If we were to glean a lesson for early childhood brain development from these studies, it would be that what children need is not necessarily a cutting-edge mobile hanging above their cribs, or a classical music tape playing as they lie down for their afternoon nap. What they do need are interesting and stimulating experiences that occur everyday, and that may or may not include these high-tech extras. Such experiences include talking, playing, singing, looking at books ?all the things that most parents can do with their young children, if they have sufficient time and an intuitive or formal understanding of their importance. To the extent possible, children need these experiences to be provided in ways attuned to their emotional and other needs, and in accord with their developmental age.
Relationships influence social and emotional functioning.
The research described above suggests how a child’s experiences early in life significantly affect brain development. Other research suggests that relationships are among the most important experiences that young children have, and that they have a particularly strong influence on social and emotional functioning. Although the connections between neurobiology and psychology between the physical and the emotional - are less well defined, we do know that one of the greatest predictors of social and emotional outcomes is a young child’s relationship with his or her primary caregiver (Sroufe, 1988). This relationship, known as an “attachment? relationship, develops when a child is between 6 and 18 months of age and reflects the sense of security the child feels in the presence of her caregiver (see Bowlby, 1969 and Ainsworth et, al, 1978). Because feeling of safety and security in the caregiver’s presence elicit particular biological responses to stress, they provide a foundation for healthy social and emotional development, and can positively affect the developing brain.
Specifically, children learn to regulate their emotional responses to events through caregiver behavior (Fox, 1998). If the attachment relationship is secure, a child learns to rely on the caregiver to help regulate her response to stressful situations and, over time, begins to self-regulate. If the attachment relationship in not secure due to inappropriate, inconsistent or ineffective behavior on the part of the caregiver, the child can experience prolonged episodes of unregulated stress and, in extreme cases, fail to develop self-regulating abilities such as the ability to calm oneself down after being startled, or the ability to put oneself to sleep. This prolonged exposure to stress hormones can even affect the synapses in the cortex, and can conceivably change the physical structure of the brain, if it occurs during the critical period of development for that region (Schore, 1996).
One group of parents whose children may be at risk for insecure attachment and prolonged exposure to stress is depressed mothers. Maternal depression occurs in mild form in approximately 40% of all mothers and in a moderate or severe form in approximately 10% of mothers during the immediate postpartum period (O’Hara, 1995). Although exacerbated by the physiological changes associated with childbirth, factors such as social support, family and spousal support, and employment play a critical role in a mother’s capacity to interact with her child. Mothers who suffer from clinical depression have difficulty responding appropriately to their infants, are often “out of sync?with their developing child, and frequently fail to respond adaptively to their infant’s emotional signals. Studies suggest that they are either more intrusive and controlling, or less attentive and engaged than nondepressed mothers (Dawson, Hessl and Frey, 1994), and observations of depressed mothers with their children can be quite dramatic: the infants smiles, the mother does not respond, and the child becomes agitated, looks away and
appears distraught.
The effect of maternal depression on children’s brains has also been measured in the laboratory. Electroencephalographic (EEG) - or brain wave - recordings demonstrate that children of depressed mothers show more activity in the frontal brain region when expressing negative emotions than do children of non-depressed mothers (Dawson, Hessl and Frey, 1994 and Dawson et. al., 1997). This pattern of increased activity indicates an attempt by the child to regulate her negative reaction to an event, yet children of depressed mothers tend to be more irritable and display sadness and anger more frequently. Thus, the attempts of such children to control their negative emotions are often unsuccessful.
Infants of depressed mothers have also been found to have higher and more persistently elevated levels of cortisol, a hormone whose levels are associated directly with stress, than do infants of non-depressed mothers (Field et. al., and Dawson, Hessl and Fray, 1994). It is thought that this indicates that these infants perceive a lack of control over their environment and that, as a result, their ability to cope with stress is significantly impaired. Other studies suggest that persistently elevated levels of cortisol are associated with atrophy of the hippocampus, a region of the brain involved in memory and learning (Sapolsky, 1996). This would suggest that it is possible that maternal depression can have a permanent effect not only on the ability of the child to feel safe and in control, but even on the child’s ability to retain memories and therefore learn.
Severe adversity significantly alters brainfunctioning
Studies of the effects of extreme social deprivation have allowed researchers to see the link between brain functioning and behavior more clearly. A recent study examined institutionalized Romanian children who had been deprived of appropriate social interaction early in life (Rutter, 1998). Some of these children, the ones who were institutionalized under conditions of severe social isolation and emotional deprivation from birth to beyond the age of 6 months had lasting social and emotional problems. Other of these children, who were removed from the institution and placed into adoptive homes prior to 6 months of age, were still able to learn normal behavior (Rutter, 1998). Like insecure attachment and maternal depression, the social and emotional problems that resulted from this extreme neglect were mediated by neuroendocrinological changes that influence how the nerve cell connections develop and function (Carlson and Earls, 1997). Scans of the brains of these Romanian orphans show that their temporal lobes have atrophied significantly, indicating that profound social deprivation can induce equally profound alterations in the physical architecture of the brain.
Do studies of severe deprivation have implications for moderate or mild deprivation? We know that relationships are one of the most significant influences on a child’s developing brain and personality. Children learn a great deal from their caregivers, including how safe their world is. Caregivers who help children feel safe while exploring and discovering new things about their world are laying a strong foundation from which their children can grow up to be happy, confident adults. Conversely, caregivers who are consistently unable to comfort and reassure children during stressful situations are potentially laying the groundwork for behavior problems, learning problems and other serious problems, as indicated in longitudinal studies of insecurely attached children. Although there is no step-by-step guide to creating a secure attachment relationship between parents and children, most parents already know how to do this. Most parents consistently give their children a warm embrace when they are hurt or afraid, and because their children come to expect this response, they know who to turn to when they fall down or encounter a frightening situation. However, factors such as depression, drug use and stress can reduce the ability of some parents to be consistently available and responsive to their children and to behave in a reliable and appropriate way. Only future research will reveal whether the behavior problems and learning problems associated with moderate or mild deprivation are associated with corresponding changes in the physical architecture of the brain, changes that might resemble the changes induced by severe deprivation. Everything we know from animal studies suggests that we must be alert to this possibility.
CONCLUSIONS AND POLICY IMPLICATIONS
The five findings that emerge from our growing understanding of neurobiology and psychology - that a child’s brain is immature at birth, that it is changed by experience, that the timing of that experience can be important, that relationships influence a child’s social and emotional functioning, and that adversity impacts brain functioning - have important implications for both parenting and public policy. They help to explain why early childhood is so important, and suggest how providing a child with a safe and stimulating environment in which to grow and develop can promote that child’s emotional well-being and cognitive success.
Although recent research has significantly advanced our understanding of human brain development, that understanding is still limited. Much more needs to be learned about how alterations in a young child’s environment affect the development of specific abilities and behaviors, and the relationship between neurobiology and psychology ?between behavior and the physical brain - also needs to be more fully understood. Although interest in the implications of brain research has increased dramatically in recent years, caution must be exercised when using conclusions from the still limited and changing body of empirical evidence to inform parenting practices or public policies. While stimulating environment can positively influence certain aspects of brain development, over-stimulating a young child can have a negative effect. Responding appropriately to a child’s cues, and modifying those responses based on the child’s subsequent responses, is part of the art of parenting. At this point, the science of brain development indicates that the art of parenting does make a difference for child development, and that policies that support parents can help them to do a better job.
The implications of the brain research reviewed here, and of numerous other studies of psychological and behavioral aspects of development, are fairly straightforward. The first implication is that the early years of life are no less important for the child’s physical, social and emotional development than the school years. Profoundly important forms of learning occur long before the child enters school, and these learning experiences do more than simply shape the cognitive content of knowledge: they shape the very architecture of the brain which will later seek and absorb knowledge in school. Parents, researchers, and policy makers have long known intuitively about the importance of infancy and early childhood, but the new brain research puts a scientific framework around these intuitions, and suggests some of the reasons that kindergarten and first grade are far too late an age to begin our communities?support for education and learning, and for the families in which much of early childhood education takes place. Brain research tells us that the lifelong process of development and learning is underway already at birth, and that we ignore the needs of families with young children at our peril. For example, literacy skills begin in an atmosphere in which parents interact regularly with their children over and around books, and those pre-literacy experiences are very likely to be shaping not just the mind and the imagination, but the connections between cells, and the architecture of the brain. Parents interacting with children around books are, quite directly, growing and shaping the brains of our future citizens.
A second implication is that, while brain research and related studies suggest that the early years are no less important than the school years for learning and development, the same research also offers tantalizing hints of how the first years may set the course for all future development. While neural and behavioral plasticity are present throughout life, the flexibility of the brain in the first years of life, and its adaptive capacity to grow and lay the groundwork for cognitive and emotional capacities in later life, is probably unmatched at any other time. It is quite possible that the developing human brain can be more efficiently and more profoundly supported and enriched in the first years of life than at any other stage. This possibility, still the subject of intensive research, is at the root of the current excitement about brain research. It is a possibility that is too important to be ignored by anyone, parents or policy makers.
A final and third profound implication of brain research is that early childhood presents itself as an investment opportunity for each community, and for our society as a whole. The investment opportunity includes the opportunity to assure that each child reaches his or her productive and creative potential. It also includes the opportunity to ensure that no child experiences deprivation that impairs brain development and imposes significant fiscal cost on school and health systems at a later date. To realize the human potential represented by infancy and early childhood, it will be increasingly important to understand the corresponding fiscal potential and costs associated with how we as a society address the needs of families with young children. It takes a well functioning family, supported by a community, to grow a brain. This simple truth about infancy and early childhood means everything for public policy.
