Developmental Changes in the Brain

Implications

• Encourage pregnant women to obtain adequate nutrition; to protect themselves from toxins, drugs, alcohol, injury, and excessive stress; and to obtain prenatal care from a physician.
• Educate adolescents (especially adolescent girls at risk for an early pregnancy) about health threats to unborn children.

Infancy

Distinctive Neurological Changes

The brain activates circuits for reflexes, sensation and perception, engagement with caregivers, and detection of patterns in the world:

• Many new connections form among neurons. Dendrites form and expand their reach and complexity, initially in brain areas that support basic biological functions and later in areas that permit learning.
• During the first year of life, synapses grow in density, especially in areas of the brain devoted to vision and hearing.
• Synaptic pruning begins in certain areas.
• Myelination occurs during infancy and continues throughout childhood, adolescence, and adulthood.

Implications

• Provide infants with the nutrition they need to build healthy bodies and brains.
• Offer infants stimulating environments that include rich visual patterns and human voices, but don't overdo it. Infants are hungry to learn about the world, but they need to do it in their own ways, on their own timetable.
• Carefully observe infants' reactions to stimuli to determine their preferences. Comment on the properties of objects, such as stripes and bright colors, that attract their attention.
• Talk to infants. They are able to learn a lot about language even when they are still unable to talk themselves.
• Form stable and affectionate relationships with infants-their brains are as busy forming emotional circuits as they are learning to perceive objects, physical events, and properties of language.

Childhood

Distinctive Neurological Changes

The brain strengthens neurological circuits used regularly and allows underutilized connections to shrivel:

• Synaptic pruning occurs with gusto in waves through distinct parts of the brain.
• The front part of the cortex (closest to the forehead), used for learning new information, controlling behavior, and planning ahead, undergoes synaptic pruning throughout childhood, adolescence, and into adulthood.
• Myelination continues to protect neurons and speed up the transmission of signals.
• The two hemispheres of the brain take on distinct responsibilities.
• Although synapses are pruned during childhood, adolescence, and adulthood, new synapses continue to be formed, reflecting learning through experience.

Implications

• Take advantage of children's growing awareness of patterns in their environment. For example, ask children to think about the nature and origin of the seasons, tidal movements, and holidays.
• Encourage children to learn more than one language-most children can easily learn two or more languages.
• In informal contexts, expose children to advanced cultural and aesthetic systems, such as music, poetry, and geometric patterns; exposure to these systems may lay the groundwork for ways of thinking that children can use in the future.

Adolescence

Distinctive Neurological Changes

The brain fortifies connections for coping with emotions and guiding actions toward long-term goals:

• Having begun in childhood, synaptic pruning in the front part of the cortex continues, allowing improvements in memory and attention.
• Myelination continues to protect neurons and speed up firing of neurons, especially in the front of the cortex, where planning and other complex cognitive processes occur.
• The cortex matures, helping adolescents integrate information from different sensory systems and engage in planning, decision making, and higher-order thinking.
• The two hemispheres of the brain continue to become specialized for different purposes.
• Circuits that support motor and speech functions continue to mature during late childhood and adolescence.
• Growth of circuits connecting language centers of the cortex slows down.
• The brain strengthens the ability of higher centers of the brain to analyze and regulate emotions.

Implications

•  Acknowledge the positive features of adolescents' newfound passions, such as creative artwork, interests in politics, and fascination with sports.
• Ask adolescents to think about the consequences of their actions for the future.
• Encourage adolescents to use their developing ability to think abstractly. For example, adolescents can systematically test hypotheses in science, contemplate the complex motivations of characters in literature, and envision multiple causes of political conflict in history classes.
• Provide opportunities for adolescents to participate in physical activity and, when they show an interest, to seek advanced training.
• Encourage adolescents to attend to the emotional expressions, experiences, and pi ights of other people.

Sources: N. R. Carlson, 1999; B. J. Casey et aI., 2000; Cowan, 1979; M. Diamond & Hopson, 1998; P. R. Huttenlocher, 1979, 1990; P. R. Huttenlocher & de Courten, 1987; l H. Johnson, 1998; Killgore et al., 2001; National Research Council, 1999; Paus et al., 1999; Rakic, 1995; Sowell, Delis, et al., 2001; Sowell et aI., 2002; Sowell, Thompson, et aI., :001; P. M. Thompson et al., 2000; Yakovlev & Lecours, 1967.