Chapter 1. Brain Development in Children 2 to 7

A long-held misconception contended that brain growth stops at birth, after which brain cells die throughout one's lifetime. Before neuroimaging was available to help us look at the workings of the brain, most neuroscientists believed that only young brains were plastic, or changeable. They believed not only that all the brain's memory-holding cells (neurons) were present at birth but also that all or most of the connections between these neurons developed in the first year of childhood and then became permanent. We now know that lifelong growth of the supporting and connecting cells enriching the communication between neurons, allied with associated increases in cognition and social-emotional skill sets, actively continues far beyond that first year.

The brain's most rapid growth occurs during gestation, when the production rate of neurons in the fetus reaches up to 250,000 per minute (Cowan, 1979). However, an intense second period of accelerated growth occurs between ages 2 and 7, followed by another rapid maturation phase extending through adolescence into the teen years.

In the first year or two after birth, most of the brain's development and activity is programmed for automatic, involuntary, reflexive, and reactive behaviors and information acquisition to ensure survival and fulfill children's basic needs. What makes this time of their lives and brain development so exciting is the accelerated rate and enhanced responsiveness with which they construct new connections between neurons. It's important to keep in mind, though, that each child develops at a unique pace. This chapter focuses on the rapid growth phase between ages 2 and 7, as their brains dramatically establish the wiring conducive to information storage, understanding, and communication.

Although experience-responsive brain growth occurs throughout our lives, the brain structures respond particularly robustly to learning experiences, environment influences, and emotional interactions during these childhood years. With maturation, brain development shifts from its focus on survival, pleasure seeking, and pain avoidance to expanded networks guiding more goal-directed skills and management of our environment, behaviors, and emotions. The brain's structural changes with this maturation are reflected in children's accelerating understanding; skills; and cognitive, social, and emotional maturation. Understanding the cellular and structural changes going on in children's brains from ages 2 to 7 provides a foundation for promoting the construction of neural networks to help them reach their greatest potential.

Neuroplasticity generates these changes in neural networks in response to learning, enhanced by each new or repeated activation of the network. Brain development and intelligence are plastic. Internal and environmental stimuli constantly change the structure and neural networks triggered by response to physical, cognitive, or emotional experiences; ideas; memory activation; or sensory intake.

Neuroplasticity is one of the most exciting areas of research in the neuroscience of learning and the brain. Research reveals evidence that all brains have the potential to become better and all students smarter, especially with guidance and encouragement. The changes that take place over time represent the lifelong growth and augmentation of the connecting cells that support and allow communication between neurons. Thus, input, experience, and practice result in enhanced efficiency of information processing by boosting neuron-to-neuron communication, with increased growth of dendrites, axonal myelin, and synapses. Dendrites and axons are the wiring that connects neurons to each other. The point of contact between the information-carrying outgoing axon and the dendrite that will carry information to the next neuron is called the synapse. Myelin is the axon power-boosting coating that is like a layer of insulation when the circuit is repeatedly used, making information travel faster and memory storage stronger.

Use It or Lose It

Part of what occurs during brain maturation is the use-it-or-lose-it phenomenon of pruning. As the most frequently used networks mature and develop more connections, myelin, and synapses, the least frequently used networks are pruned away. This process increases the brain's efficiency and strengthens those networks used most often. It also increases the brain's efficiency to allow more of its limited supply of oxygen and glucose to be available for the most active pathways.

Pruning intensifies during the third or fourth year of life, when it includes neurons not used as part of connecting circuits and small connections of neurons, axons, and dendrites receiving little activation. This process is visualized on imaging as thinning of the cortical gray matter strip, which forms the outermost part of the brain.

Because pruning depends on which information is used, the environment plays an increasingly important role in determining which connections are maintained or lost in children's brains. A give-and-take streamlining process takes place, as eliminating excess material allows more efficient processing. As the number of small, unused neuronal circuits decreases, the number of neural connections expands in response to use, and the brain develops into a much faster and more sophisticated organ. Because of this plasticity, teachers, parents, and caregivers become the brain changers who can promote learning by providing experiences that activate children's neural networks, allowing their brains to construct meaningful memories and knowledge.

Practice Makes Permanent

Memory can be thought of as the construction, expansion, and strengthening of neural networks in response to activation. Let's now consider what factors influence the construction of durable memory networks. Each time a network holding a memory is activated—perhaps the meaning of a word or a skill such as kicking a ball—the neuroplastic response is stimulated, strengthening the networks of connections among the neurons, each holding pieces of the memory. It is the mental manipulation of learning (practice, rehearsal, using information in new ways) that makes these networks grow stronger, faster, and more durable (Chang, 2015; Neumann, Lotze, & Eickhoff, 2016).

During their early years, children learn very quickly through experience. A child's natural curiosity drives investigation, careful observation (visual and auditory), and motivated memory construction. Reading favorite books to children is one example of how strong memories are built. These memories are embodied by children's accurate and enthusiastic verbal predictions of "what comes next." Information driven by curiosity, personal relevance, and association with pleasure or satisfaction is more likely to be remembered when it is carefully observed and revisited, particularly when it is experienced through multiple senses (Thomas, 2016).

New memories of information, tasks, and skills must be activated or practiced, or they will be pruned. Even if instruction—say, for decoding words during the last month of school—is successful, the same literacy skill may not carry over to the following school year. It takes practice, repetitive use of the pathway, and review to retain stored learning in neural networks. If students do no further work with the words for the intervening months, pruning will likely eliminate many of the constructed networks.

Regions of Brain Maturation During Childhood

The growth and pruning process that takes place in response to activation or use of the circuits continues through our lifetime. On a larger developmental scale, whole regions of the brain follow a predictable, age-related, regional progression of growth and pruning described as maturation. The physical changes in a region undergoing its rapid maturation phase essentially consist of accelerated neuroplasticity. There is more vigorous pruning of the networks previously constructed but unused, and a more exuberant myelination of the networks that are activated and used most frequently.

The cerebral cortex is where the maturation process, with its phases of cognitive and emotional development, is most evident. The cerebral cortex comprises the outer layers of the brain. The outermost layer, gray matter, and below that a thicker layer, white matter, constitute the majority of the cerebral cortex. Gray matter consists of neurons, end branches of axons, dendrites, and synapses. White matter is so named because it contains bundles of myelinated axons. The white color of the myelin gives the region its lighter color.

The changes related to childhood brain maturation involve phases of increases in gray matter, followed by decreases overlying an ongoing accumulation of white matter (Shaw et al., 2006). Gray matter first goes through its most accelerated phase of maturation in the posterior and lower regions of the brain (directing the basic functions, such as digestion, and driving the rapid, reactive responses to perceived threat or unexpected change). Next to undergo rapid maturation, peaking between ages 3 and 5, are the sensory and motor control centers of the brain. This sequence seems logical, considering that younger children experience their world through their senses and continually build their motor skills to more successfully satisfy their needs and later their curiosity.

These peaks are followed by a more gradual reduction in gray matter over a period of years. Many of the connections and small networks constructed during the young child's early experiences are inconsistently reactivated (recalled, experienced, used) and thus pruned. The more accelerated phase of growth between ages 5 and 7 takes place in the higher cognitive and social-emotional processing regions of the prefrontal and temporal lobe cortices. Subsequently the frontal lobes display more active pruning and myelin formation as neural networks of executive function develop. This is the last and longest rapid maturation phase, extending through the teens into the early 20s (Gogtay et al., 2004).

As we age, the size of the cerebral cortex grows, augmented by learning and experience. The expansion of myelin and the ever-increasing extension of dendrites and synapses connecting neurons into circuits of related information amplify rapid and efficient communication between neurons in the maturing cortex. The thicker layering of myelin speeds the transmission of the electrical messages, enabling them to jump over sections of the axon (a process called saltatory conduction) rather than having to travel more slowly through its entire length (Shaw et al., 2006).

Activating Brain Networks During Their Accelerated Maturation

Considering that maturation in the brain increases its efficiency, it follows that the brain is more responsive to molding of its neural networks during children's rapid maturation periods of heightened neuroplastic response. Recognizing which regions are undergoing rapid maturation at a particular time should not limit learning experiences to these phases of brain development alone. The brain continues to be responsive throughout life. Nevertheless, such recognition can help promote awareness of types of experiences and environments that might be most fruitful at any given stage.

For example, between ages 3 and 5, during peaks of rapid maturation of the sensory and motor control centers of the brain, children are particularly engaged by sensory and motor experiences. Consider the eagerness preschoolers have for exploring objects through multiple senses, exemplified by their tendency to jump into every puddle they pass. These are also "sweet spots" in time for experiencing the Habits of Mind. Later, as children's brains begin the more vigorous phase of growth in the prefrontal and temporal lobe cortices, the potential arises to promote neuroplastic growth in the regions associated with higher cognitive and social-emotional processing.

Development of the Neural Networks of Executive Functions

As noted earlier, the neural networks that direct executive functions develop in the prefrontal cortex and begin their extended maturation starting around age 5. These networks are what give children increasing voluntary control over their attention focus, inhibitory control, delay of gratification, emotional self-awareness and self-management, interpersonal relationships and empathy, goal-directed behavior, planning and prioritizing, critical thinking, judgment, reasoning, and flexibility of thinking and adaptability. All these executive functions contribute to a child's potential to achieve a fulfilling and joyful life.

Although this section focuses on the prefrontal cortex developing executive functions, other foundational experiences and exposures are strongly linked to success in school and life. For example, there is a strong association between parents' language use and interaction patterns and children's language development (Huttenlocher, Vasilyeva, Cymerman, & Levine, 2002).

Research supports the idea that the strength of children's executive functions serves as one of the best predictors of school readiness, including social-emotional and academic competence and the development of literacy and numeracy (Allan, Hume, Allan, Farrington, & Lonigan, 2014; Kim, Nordling, Yoon, Boldt, & Kochanska, 2013). Using brain imaging and monitoring of the electrical signals produced by activated brain networks, we can see evidence of increased response in children's developing neural networks of executive functions when they are activated and used. For example, activation of the prefrontal cortex is seen in young children when they use the executive function networks for behavioral inhibition, such as suppressing an automatic response during delay of immediate gratification (Stevens & Bavelier, 2012).

Given the central role of executive functions in school readiness, and the correlation of early school success with later success in school and life, it is relevant to consider which executive functions are most strongly correlated with that readiness and how interventions could enhance the neuroplastic strengthening of these networks during early childhood. A study of 100 children ages 2 to 5 evaluated their performance on a variety of tasks that rely on executive functions in relation to academic and social school readiness. The findings indicated that the ability to delay gratification was a manifestation of developing social-emotional skills, such as self-regulation. Along with inhibitory control (the ability to filter irrelevant information), skills of self-regulation were prominent predictors of academic readiness (Mann, Hund, Hesson-McInnis, & Roman, 2017)—a finding that relates to such Habits of Mind as managing impulsivity, thinking about thinking (metacognition), and listening with empathy. This and other studies provide support for the importance of the development of social-emotional as well as academic competence in preparing children for school readiness, peer relationships, positive attitudes toward school, emotional self-management, and academic achievement (Blair & Razza, 2007; Mann et al., 2017; Razza & Raymond, 2015).

Additional studies evaluated neuroplastic growth and brain network strength in children burdened by delays, high stress, and low socioeconomic environments. These studies linked improvements in children's attention, cognition, and language to interventions designed to increase activation of their executive function networks (Neville, Stevens, & Pakulak, 2013; Stevens, Lauinger, & Neville, 2009).

Because low-functioning foundational neural networks related to executive function and cognition can have extensive consequences for later learning, it is reasonable to promote the environments and experiences that are linked to promoting more successful development (Blair & Razza, 2007; Razza & Raymond, 2015). Recommendations for promoting activation of components of the executive function networks for all children during these early years—through facilitated play, games supporting inhibitory control, building empathy, and parental guidance—are a vital part of the content of this book. The rest of this section will suggest categories or characteristics of some interventions supporting the developmental opportunities in young children's brains.

Attention Focus and Goal-Directed Behaviors

The executive functions have numerous isolated aspects that can be activated with deliberate attention focus and plans or actions to achieve specific goals. The distinctions are useful both for research specificity and guidance for recognizing opportunities to promote the activation of these executive function networks. For example, distraction inhibition and sustained focus are built into games like Follow the Leader; Red Light, Green Light; and Simon Says. Delay of gratification is another self-control component; this skill set gained attention with the research by Walter Mischel and colleagues in the 1960s and '70s that has come to be known as the Marshmallow Test. After developing an initial play activity with the researcher, a 4- or 5-year-old child was shown a marshmallow and promised a reward of two marshmallows for waiting until the researcher came back (15 minutes later). The reported correlations 10 and more years later found that the children who could delay gratification and wait for the two marshmallows had (on average) higher SAT scores, more job satisfaction, higher income, more stable marriages, and better health (Mischel, Ebbesen, & Raskoff-Zeiss, 1972; Mischel, Shoda, & Rodriguez, 1989).

Opportunities to help children build their delay of gratification or other impulse controls are abundant. They may simply consist of being aware of not wresting control away from children but rather helping them recognize the consequences of taking a toy away from a friend or not waiting their turn by recalling how they felt when they were the target of others' impulsive behaviors. Identifying the benefits of successfully delaying immediate gratification to achieve a goal (for example, by taking the time to look for things they need to bring home from the classroom instead of racing out the door when dismissed) has a similar impact. This skill set is what children need to persevere when facing the challenges and setbacks natural to the processes of developing literacy, building successful collaboration skills, and achieving emotional self-management.

As children reach preschool age, there are opportunities to help them recognize both their self-efficacy and goal-building strategies. Registering their progress and sustained efforts, rather than just the end products, is useful. When children are prompted to predict what they will need to do next or in an upcoming situation—for example, what type of voice they will use when they get to the library or what supplies they'll need to keep a new goldfish healthy—they activate goal planning.

Building skills to take on challenges, overcome obstacles, and persevere after mistakes is essential to developing the executive functions of sustained attention focus and goal-directed behaviors. Young children are just beginning to wire in these control systems, and they need opportunities to activate skills to increase their tolerance for frustration.

Conversations about "what if?" can promote children's thinking about strategies and opening themselves to alternatives. These questions could be asking them what they could do if they saw two friends pushing to get to the same toy or to think about what has made them happy in past times when they were sad. Ultimately, providing more and more time for them to struggle before stepping in will promote their own resilience and self-directed control networks.

Judgment and Flexible Thinking

Building children's self-management as they develop their neural networks and skill sets allows them to be consciously aware of, and to control, their emotions and work toward goals. This skill will guide their future decision making, judgment, and peer relationships.

Opportunities to help activate their developing executive function networks for judgment and flexible thinking are most authentic and meaningful when integrated into their daily experiences and activities. These can start with choices about clothes to wear or food options and ultimately evolve to richer decisions about relationships as they consider how their behavior affects others.

Opportunities to promote flexible thinking (cognitive flexibility) can further activate developing neural networks related to executive function. When giving young children a new toy, instead of showing them the "right" way to use it, encourage them to first explore it independently. They will often sustain interest longer and find innovative ways to engage with it.

Guide children to recognize how differences can be positives when exploring unfamiliar playgrounds, new cities, or diverse cultures. They can experience information through multiple perspectives, such as the variety of translated versions of the Cinderella story as represented in other countries or putting themselves into the persona of several different characters in a book.

Emotional Self-management

We recognize that emotional development takes place throughout life. Notably, though, it is during the early years that the increased sensitivity and responsiveness in the regions of the brain associated with higher cognitive and social-emotional processing serve all children especially well. Recall that the cortical networks most responsible for coordinating emotional responses in the prefrontal, temporal, and parietal cortices are highly active in neuroplastic growth and pruning during these years. The cross-connecting among these regions has distinctive relevance in emotional development. What we see is burgeoning wiring evolving in the myelinated communications between subcortical emotional response areas and those regions of the prefrontal cortex that make up systems for control of executive function. These "top-down" communication networks under construction in their brains are critical for successful emotional processing, rational thinking, judgment, goal-directed behaviors, interpretation of social or emotional cues, and decision making.

An example of one such development is the social interaction skills that begin to emerge around age 3 as children become more aware of and responsive to the gestures, facial expressions, and actions of others and begin to connect these interpretations to what the other person is feeling. This awareness reflects the development of stronger communication between the neural networks in the prefrontal cortex and those that direct emotional processing in the amygdala and related regions of the temporal lobe.

If the sensory input from a facial expression to the amygdala is simultaneously accompanied by strong emotions, such as pleasure, happiness, fear, or anxiety, the previously neutral sensory input becomes identified with the emotion in an associational neural network. Those linkages, if reinforced, lead to more automatic or generalizable emotional interpretations of facial expressions. This example illustrates how children develop the emotional patterns or association learning that triggers the brain to respond to future similar input or experiences.

Because the reinforced associations children develop become solid neural response networks, it becomes critical to observe their responses and intervene if they are developing strong negative associations. This situation might emerge when associations are incorrect, hurtful, or limiting, and they can undermine children's future social and emotional foundations. Guidance and interventions can be framed around experiences that build children's understanding of and respect for others.

As they build empathy, children activate their communications for "top-down" executive management for reflection instead of automatic reactions. Helping them with opportunities to understand and incorporate other points of view will promote their facilities for building peer relationships with warmth and trust.

Using the example of building higher-order processing of emotions by increasing awareness of emotional cues, teachers can provide guided experiences, such as asking children to interpret the meaning of facial expressions as they read books and hear stories. When children are prompted to describe how a person with a clear facial expression is feeling, they are moving toward the goal of reflecting on other people's perspectives as guides to their interactions. By identifying emotions depicted in emojis, picture books, and stories, children can be primed to be more aware of and verbal about their own emotions. When they can identify their feelings, they will be more facile at accessing the neural networks needed to calm themselves or reflect before acting. Guided play with other children in which they take on the characters of people in different jobs, or of different ages or backgrounds, provides experiential opportunities for them to further expand their perspectives.

As children get older and develop more control over executive function, there are increased opportunities to promote more independent self-management of emotions through their peer interactions. Again, not jumping in with immediate solutions helps them to build their skill sets of handling interpersonal conflicts constructively, allowing them the chance to experience their emotions and the consequences of their actions—good and bad.

Teaching children ways to calm themselves so they can better maneuver through their interactions with others takes time, guidance, and practice. However, these efforts provide profound value as children are exposed to ever-increasing stresses. We know that chronic stress can have a negative impact on areas of brain development critical to memory, attention, language, and cognition; and coping tools built early will reduce the impact of later stressors (Lupien, McEwen, Gunnar, & Heim, 2009).

Young children's emotional responses are still strongly influenced by the "bottom-up" feed from the emotionally reactive amygdala and their brain's instinctual drives to seek pleasure and avoid pain, real or imagined. Just suggesting strategies to ameliorate stress, such as counting to 10, deep breathing, or mindfulness, though perhaps useful in the moment, is inadequate to promote the strong, fast, and easily retrievable control networks that young children need to self-manage and override their immediate, involuntary reactions.

It takes guided experiences over time, providing frequent opportunities for children to stimulate these neural network control systems, for emotional self-awareness and self-management to be incorporated as Habits of Mind. The repeated practices of self-calming strategies, including mindful breathing, calming visualizations, and activating optimistic memories, will facilitate the neuroplasticity that builds the dendrites, anonal myelin, and synapses. With those strong, durable, easily retrievable neural networks, children will have automatic, rapid access to these valuable skills whenever they are needed.

As you read this book, you'll acquire tools to help children reach their highest potential as joyful learners by engaging their brains' neuroplasticity. As the important brain changers you are, you'll gain more awareness and the skill sets to promote those learning environments and experiences that activate children's neural networks. They will develop the tools needed to construct knowledge about themselves and their world and the Habits of Mind needed to embrace the challenges and opportunities that lie ahead.