A developing brain

A developing brain
Before birth and during early childhood, a baby’s brain is in a period of intense growth, for everything has yet to be learned. Here’s a look at what’s happening inside your little one’s head.

Before birth and during early childhood, a baby’s brain is in a period of intense growth, for everything has yet to be learned. Here’s a look at what’s happening inside your little one’s head.

Babies grow so fast! A few weeks after they’re born, their first pyjamas are already too small. And though the process is invisible to the naked eye, their brains are growing just as fast.

A newborn’s brain weighs about a quarter the weight of an adult’s brain. "During the first year of life, the brain doubles in volume, and between ages three and four, it triples," says Miriam Beauchamp, director of the ABCs Developmental Neuropsychology Lab at the University of Montreal and a researcher at the CHU Sainte-Justine Research Center. Every new milestone your child reaches or new skill they learn is a sign of this growth. Smiling, babbling, holding a spoon, playing, walking—all of these are linked to the development of their brain.

Even during pregnancy, children’s brains are growing. Several thousand neurons are created every second. When babies are born, their brains have about 100 billion neurons—all the neurons they will need throughout their lifetime, and more.

For the brain to function, these neurons have to connect to one another. The first connections occur before birth. "In the mother’s womb, babies hear sounds and voices: they move and feel the sensation of the amniotic fluid," says Beauchamp. "These stimulations help improve the connections between the neurons."

A nimble brain

After birth, the connections continue to multiply. Billions of them will be created throughout your child’s first years. Every time your little one learns something, connections form in her brain. At the same time as connections are being created, others are solidified, while still others (those that aren’t being used) are eliminated. This ability of the brain to rewire its own connections is called neuroplasticity.

Did you know?
The connection between two neurons is called a synapse. Every kiss, every diaper change, every game—every experience influences the creation of new synapses. These connections are essential to the development of your child’s brain.

"The connections that are used the most become stronger, and those that are unnecessary or deficient are eliminated," says Beauchamp. "It might seem strange that the brain gets rid of certain connections, but it’s a necessary process. It makes the brain more efficient. Think of it like a tree that you make stronger by pruning the damaged branches."

The brain is at its most pliable during early childhood, when it is developing most rapidly. It modifies itself to adapt as the child grows and learns new things.

Neuroplasticity can also help toddlers recover after a brain injury. For instance, if an injury occurs in one area of the brain, neurons in other areas may take over and make new connections. "That doesn’t mean there won’t be consequences for the child," warns Beauchamp. "Their brain will try to recover, but unfortunately, depending on the severity of the situation, there could be negative physical, cognitive, social, or behavioural effects."

Environmental influences

The brain’s ability to modify its connections has advantages, but it also carries some risk. Upsetting experiences affect a toddler’s brain more than that of an older child. Likewise, when a young child isn’t stimulated enough, the brain doesn’t develop as well because many neural circuits aren’t used.

Did you know?
When children are stimulated, have varied experiences, and are surrounded by people who love and take care of them, their brains develop better.

The first years of life are therefore very important for brain growth. That’s why parents play such a big role. When you care for, comfort, and give affection to your child, or talk to and play with him, you are helping his brain develop properly.

Your baby also needs to sleep and eat well. "When your child is sleeping, his brain may be resting, but it’s not inactive," says Beauchamp. “The brain consolidates what it has learned by committing it to memory and continues to make connections between neurons."

What role does genetics play in brain development? "Brain development is the result of a complex interaction between genes and the environment in which a child is raised," says Linda Booij, associate professor in the Department of Psychology at Concordia University and a researcher at the CHU Sainte-Justine Research Center. "Gene activity can be altered by a child’s experiences, even during pregnancy. That means that what happens during pregnancy can influence the genes of the unborn baby."

When does a child’s brain stop growing? Science doesn’t have all the answers to this question yet. What we do know is that most areas of the brain reach maturity around the age of 25. After that, connections continue to be made and unmade, but more slowly than during childhood.


Is stress bad for the brain?

The first day of daycare, a doctor’s appointment, moving to a new home—when children experience stressful situations, their brain triggers the production of a stress hormone called cortisol. This hormone helps them adapt to the situation and cope better. "Normal, everyday stress is helpful," explains Booij. "Stress becomes harmful when it’s prolonged, frequent, and intense. This is called chronic or toxic stress." An abused child or one who witnesses serious family conflicts, for instance, may experience toxic stress.

This type of stress is bad for a developing brain. The child could end up at greater risk of developing mental health problems later on. "But all is not lost, because a child’s brain is highly flexible," explains Booij. Indeed, many studies show that care, affection, and strong relationships during early childhood can offset the negative effects of chronic stress.


Photos: GettyImages/krystynataran


Naître et grandir

Source: Naître et grandir magazine, September 2018
Research and copywriting: Nathalie Vallerand
Scientific review: Dr. Tuong-Vi Nguyen, Assistant Professor, Department of Psychiatry, Faculty of Medicine, McGill University