A newborn baby’s brain weighs 400g, and as a child interacts with their parents and siblings, they begin to learn language and even numbers. At the age of 4 to 5, the weight of the brain reaches 1200g, which is about 90% of adults (around 1300g to 1400g).
There are tens of billions of nerve cells, and each nerve cell has a number of nerve fibers. The weight of the brain grows as nerve fibers that connect the cells grow. In particular, the prefrontal cortex is said to grow even up to around 20 years of age.
In a child’s brain, many neural circuits are created in the early stages of development and unnecessary nerve fibers that are not used are removed as they grow. This is called synaptic pruning. Nerve fibers that are frequently used and have a large amount of information become thicker and can grow into a strong neural circuit.
The strengthened neural network can transmit a large amount of information at high speeds so that information processing ability can be even faster. Thus, to strengthen the neural circuit, it is necessary to perform and learn a task repeatedly to make the brain work actively. This way, if you learn and experience various things by around 20 years of age, the brain can grow and develop even further.
Of course, it doesn’t mean that the brain doesn’t develop after 20 years of age, but it is only up to this age where the effects can be noticed, which is in part due to the human body peaking its growth at around 20 years of age.
Early childhood, elementary school, junior high school, and high school are important times when the brain develops and grows the most.