Question

How does the brain change during Infancy?

What characterizes the development of the brain in childhood?

Answer 1

• The synapses a child is born with govern functions like a child’s heart rate and breathing, eating and sleeping. However, during the child’s early years, synapse development in response to the child’s experiences is fantastically fast.By age 3, the child’s brain has reached nearly 90 percent of its adult size; the growth in each part of the brain depends in a majority on receiving stimulation.
• Myelin is tissue that insulates brain cells with a sheath that ensures clear transmission across synapses; the reason young children process information slowly is because their brain cells lack myelin needed for quicker transmission of nerve impulses.
• The early stages of development are strongly affected by genetic factors; for example, genes direct newly formed neurons to their correct locations in the brain and play a role in how they interact.
• Genes allow the brain to fine-tune itself according to the input it receives from the environment. A child’s senses report to the brain about her environment and experiences, and this input stimulates neural activity. Speech sounds, for example, stimulate activity in language-related brain regions. If the amount of input increases (if more speech is heard) synapses between neurons in that area will be activated more often.
• The first key event of brain development is the formation of the neural tube. About two weeks after conception, the neural plate, a layer of specialized cells in the embryo, begins to slowly fold over onto itself, eventually forming a tube-shaped structure. The tube gradually closes as the edges of the plate fuse together; this process is usually complete by four weeks after conception. The neural tube continues to change, eventually becoming the brain and spinal cord.
• About seven weeks after conception the first neurons and synapses begin to develop in the spinal cord. These early neural connections allow the fetus to make its first movements, which can be detected by ultrasound and MRI even though in most cases the mother cannot feel them. These movements, in turn, provide the brain with sensory input that spurs on its development. More coordinated movements develop over the next several weeks.
• Early in the second trimester, gyri and sulci begin to appear on the brain’s surface; by the end of this trimester, this process is almost complete. The cerebral cortex is growing in thickness and complexity and synapse formation in this area is beginning
• The early weeks of the third trimester are a transitional period during which the cerebral cortex begins to assume many duties formerly carried out by the more primitive brainstem. For example, reflexes such as fetal breathing and responses to external stimuli become more regular. The cerebral cortex also supports early learning which develops around this time.
• The remarkable abilities of newborn babies highlight the extent of prenatal brain development. Newborns can recognize human faces, which they prefer over other objects, and can even discriminate between happy and sad expressions. At birth, a baby knows her mother’s voice and may be able to recognize the sounds of stories her mother read to her while she was still in the womb.
• The brain continues to develop at an amazing rate throughout the first year. The cerebellum triples in size, which appears to be related to the rapid development of motor skills that occurs during this period. As the visual areas of the cortex grow, the infant’s initially dim and limited sight develops into full binocular vision.
• At about three months, an infant’s power of recognition improves dramatically; this coincides with significant growth in the hippocampus, the limbic structure related to recognition memory.
• During the second year, there is a major increase in the rate of myelination, which helps the brain perform more complex tasks. Higher-order cognitive abilities like self-awareness are developing: an infant is now more aware of his own emotions and intentions. When he sees his reflection in a mirror, he now fully recognizes that it is his own. Soon he will begin using his own name as well as personal pronouns like “I” and “me.”
• Synaptic density in the prefrontal cortex probably reaches its peak during the third year, up to 200 percent of its adult level. This region also continues to create and strengthen networks with other areas. As a result, complex cognitive abilities are being improved and consolidated. At this stage, for example, children are better able to use the past to interpret present events. They also have more cognitive flexibility and a better understanding of cause and effect.