Top 10 Questions About Child’s Brain Development – Brain Health Series Part 1

Q: Does brain development depend only on genes?

A: No, brain development is the result of a complex interaction between both genes and environment. Brain development begins in utero. Billions of neurons are generated. They migrate from their birth place in the embryo to their final positions. Axons and dendrites grow and connections (synapses) between neurons are formed. These mechanisms are believed to be hardwired, that is determined by genetics. Once connections are formed, activity dependent mechanisms come into play. Whether a connection is strengthened or eliminated will be determined by the activity of this connection, that is, it will depend on the experiences of the baby/child.

An example of how the environment can influence brain development: Rutter et al. (1998) studied Romanian orphans brought to England and adopted before age two (some before 6 months). When assessed on arrival, the babies were shown to be severely developmentally impaired and malnourished. When tested again after several years in the adoptive environment (at age 4), the children showed great physical and developmental progress, especially those adopted before 6 months.

Q: So, can a child outsmart his/her genes?

A: Yes, that can be done says Richard Nisbett author of “Intelligence and How to Get It: Why Schools and Cultures Count”. In this interview, Nisbett explores the interaction between genes, school and intelligence: “If our genes largely determine our IQ, which in turn underlies our performance throughout our lives, then what is the role of school?”

In this other interview, exchild prodigy Joshua Waitzkin’s, American chess player, martial arts competitor, and author, explain Synapse xt s how a lot depends on learning about learning.

Q: Are babies born with more or with less neurons and synapses than adults?

A: Babies are born with more neurons and thus synapses than adults. In a study conducted in 2007, Abitz, Damgaard et al. compared 8 newborn human brains with those of 8 adult brains and showed that on average, adult neuron estimates were 41% lower than those of the newborn. What happens to these extra neurons and connections then? The answer is synaptic pruning (or neuron pruning).

Synaptic pruning is a regulatory process that reduces the overall number of overproduced neurons by “weeding out” the weaker synapses. A weak synapse is a synapse that is not used much, which shows that experience is an essential part of brain development.

Q: Is under 5 THE ONLY critical period for brain development?

A: No. Brain development is a continuum from birth to age 20 or so. A “critical period” in development is a time, in the early stages of an organism’s life, during which the organism shows a very high sensitivity to some stimuli in the environment. If the stimuli in the environment are present, the organism will develop in a specific way. If the stimuli are not present during the critical period, it may be difficult, or sometimes impossible, to develop some functions. For example, if an infant does not see light during the first few months of life (at least 6 months), nerves and neurons processing visual input will degenerate and eventually die.

The most wellknown example of critical period comes from the Critical Period Hypothesis (Lenneberg, 1967), which states that the first few years of life constitute the time during which language develops easily. After that learning a language is more difficult and usually less successful.

Is it the case however that “everything happens before age 5″? Would age 0-5 be a critical period for all major cognitive skills? No. Development is more a trajectory, a continuum. Brain imaging studies and other research show that the brain is not fully developed until age 18 to 20. In particular, the frontal lobes of the brain the part involved in judgment, organization, planning and strategizing are the last ones to be wired to function like an adult.

Written by


Leave a Reply

Your email address will not be published. Required fields are marked *