Which of the following brain development processes takes place rapidly during the first two years?

Which of the following brain development processes takes place rapidly during the first two years?

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The first months and years of life mark the most rapid periods of growth and development for the human brain. The neural pathways that develop during this time lay the foundation for the people we will become.

After 40 weeks in the womb, a baby’s brain weighs about 370 grams (or 13 ounces). Just shy of a pound, it accounts for a remarkably large percentage of an infant’s body weight. Compare that to the average adult brain which weighs three pounds and makes up only 2% of body mass.

The rapid pace of development continues after birth. The brain grows by about 1% per day for the next three months before slowing to a rate of 0.4% per day. At this point, a baby’s brain is 64% larger than it was at birth.

That increase is the result of brain cells multiplying, growing, maturing, and migrating to different brain regions. During those first three months, the number of neurons in the cerebral cortex — the wrinkled, outer layer of the brain — increases between 23 and 30%. The fastest-growing brain region is the cerebellum. It more than doubles in volume by three months. The cerebellum contains more neurons than any other brain region and it helps with motor control and movement — key skills for babies as they explore their world.

Other kinds of cells also grow and multiply in the brain. Support cells called oligodendrocytes wrap nerve fibers with insulating myelin to speed the transmission of electrical signals. Myelin bulks up the brain and gives white matter its characteristic color.

Neurons grow longer dendrites and axons, which allow them to make more connections, or synapses, with other cells. The number and density of synapses increase rapidly during the first years of life. A 2-year-old’s brain is about 20% smaller than an adult brain but has 50% more synapses. Maintaining that many synapses would demand far too much energy and other resources, however. So, during early childhood, the brain begins to pare back synapses and fine-tune the connections. Experience — sensory stimulation and interactions with caregivers and their environment — drive this synaptic pruning process as toddlers grow. Just as pruning rose bushes gets rid of weaker branches to allow nutrients to go to the stronger branches, synaptic pruning culls weaker connections while helping more active synapses grow and stabilize.

By the time a child turns 5 years old, the brain has reached about 90% of its adult size. That still allows for plenty of growth and change during childhood, adolescence, and early adulthood.


Adapted from the 8th edition of Brain Facts by Jill Sakai.

About the Author

Which of the following brain development processes takes place rapidly during the first two years?

Lindzi Wessel

Lindzi Wessel is a freelance science journalist who graduated from the UC Santa Cruz Science Communication Program. Before turning her sights on journalism, she studied the mind, obtaining a bachelor’s degree in psychology and a master’s in neuroscience from UC Davis. For the moment, she resides in Santiago, Chile, where she’s learning about science coming out of South America.

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Which of the following brain development processes take place rapidly during the first two years of life?

Like other areas of the brain, the sensory and motor cortices develop rapidly in the first two years of life. As you would expect, this leads to several important developmental milestones. Though every child develops at their own pace, there are some things that are common in many infants at different points.

What stage of the brain is rapid development?

From birth to age 5, a child's brain develops more than at any other time in life. And early brain development has a lasting impact on a child's ability to learn and succeed in school and life.

What happens to the brain at 2 years old?

Between the ages of 2 and 3 your toddler's brain power increases at an astonishing rate. The improvements in their thinking, learning and memory skills give them all kinds of new ways to play, explore and express their opinions, not to mention demands for cuddles.

What part of the brain develops faster?

These brain regions play an important role in functioning in social and emotional situations and are known to be sensitive to stress. Stress due to negative experiences during childhood , such as illness or divorce, appears to be related to faster maturation of the prefrontal cortex and amygdala in adolescence.