April 28, 2015
Story by Jacqueline Louie and Nicole Sherren
Our brain is our most complex organ. It’s a command centre for everything we think, do and feel. We’re born with almost all the brain cells we’ll have throughout our lives, so our brain doesn’t grow as much as it develops.
To do this, it needs neural connections—billions of them. These connections—called synapses—are tiny, each about 10,000 times smaller than the thickness of a piece of paper.
The basic architecture of the brain is built over time, beginning before birth and continuing until we’re adults, with more connections forming in our first six years than at any other time in life. During our early years, our brain makes about 700 new neural connections every second—billions by the time we’re three years old.
It’s no wonder toddlers are bursting with life, energy and curiosity.
As we grow, our brain continues to form new neural connections at a slower rate. At the same time, our brain also goes through synaptic pruning, shutting down some circuits that are not used so the remaining ones can become more efficient. Harvard University’s Center on the Developing Child says our early experiences “affect the nature and quality of the brain’s developing architecture by determining which circuits are reinforced and which are pruned through lack of use.” This is sometimes called “use it or lose it.”
“The more you use a brain connection, the more likely it is to become strong and to last a lifespan,” says Judy Cameron, a professor of psychiatry at the University of Pittsburgh, where she serves as director of science outreach.
Neural connections are formed and pruned in a set order, with the simplest circuits (groups of connections) coming first and the more complex circuits coming after. The process begins with sensory circuits (such as seeing and hearing) followed by language skill circuits. Next are circuits for more complex functions such as controlling emotions, social skills, abstract thinking and problem solving. Our brain development usually wraps up when we’re between 25 and 30.
Our genes determine the exact timing of this development, and our experiences throughout life determine which connections are reinforced and which ones are pruned, leading to either weak or strong circuits. The brain is never a blank slate, the Center on the Developing Child says. Every new skill is built on those that came before.
The building block of brain architecture is serve and return interactions.
Serve and return exchanges are often “really easy things to do that will have a huge impact on the rest of a child’s life,” says Bryan Kolb, a University of Lethbridge professor of neuroscience and Board of Governors Research Chair in neuroscience. Reading together, he adds, is one good form of serve and return. “You are interacting one-on-one and talking to them."
