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Early Brain Development: Critical and Sensitive Periods

Q: I heard from my friend that first 3 years of child's life is very important for brain development. and there are critical periods and sensitive moments in a child's life for brain development. Could u please explain more to me. Thanks.

A: This is indeed true and involves a dynamic interplay of nature and nurture. Research in early brain development has highlighted up to the age of three for these periods.

To understand how this really work, I would refer to an article written by Sara Gable ( State Extension Specialist, Human Development) 2004 - Nature, Nurture and Early Brain Development.

At birth, the human brain is still preparing for full operation. The brain's neurons exist mostly apart from one another. The brain's task for the first 3 years is to establish and reinforce connections with other neurons. These connections are formed when impulses are sent and received between neurons. Axons send messages and dendrites receive them. These connections form synapses.

As a child develops, the synapses become more complex, like a tree with more branches and limbs growing. During the first 3 years of life, the number of neurons stays the same and the number of synapses increases. After age 3, the creation of synapses slows until about age 10. Between birth and age 3, the brain creates more synapses than it needs. The synapses that are used a lot become a permanent part of the brain. The synapses that are not used frequently are eliminated. This is where experience plays an important role in wiring a young child's brain. Because we want children to succeed, we need to provide many positive social and learning opportunities so that the synapses associated with these experiences become permanent.
How the social and physical environments respond to infants and toddlers plays a big part in the creation of synapses. The child's experiences are the stimulation that sparks the activity between axons and dendrites and creates synapses.

There are essentially two crucial periods for brain development; the critical periods and the sensitive periods as you may have heard of. Critical periods represent a time when a particular part of the body is most easily influenced or vulnerable to the lack of stimulation or to environmental effects. For example, if an infant does not see light during the first few months of life (at least 6 months), nerves will degenerate and eventually die. This period also includes prenatal development; what the mother consumes may have an impact on prenatal development of the foetus.

On the other hand, sensitive periods refer to opportunity for certain types of learning, that is less precise and a longer time period compared to critical period. During this period, if there is a lack of opportunity for a certain type of learning, it is not gone forever (as it is for critical periods). Skills can still be acquired at a later stage in the individual’s lifespan. However, skills acquired during the sensitive period makes the individual better than another who did not acquire those skills then. For example, socio-emotional and certain cognitive traits that makes one person very different from the other. Therefore, this period is crucial from birth to three years of age.

Informative readings on critical and sensitive periods for brain development: Invest in Kids, Zero to Three

An article on this for Language Development could be found at Social Issue Reference

Hope that helps a little.

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