How Neuroplasticity Changes Over Your Brain’s Lifetime

From the day you’re born, your brain is continuously being rewired and functionally revised through an ability known as neuroplasticity. In the newborn brain, plasticity is always turned “on”. As a brain matures and generates more reliable and coordinated responses, it becomes more selective about what it allows to alter it. In other words, the “off” switch for neuroplasticity becomes more powerful and dominant. Permanent changes are then most often permitted only under certain circumstances.

However, the adult brain can and does change, and you can learn to direct the process.

What Is Neuroplasticity?

Neuroplasticity is an umbrella term referring to the many capabilities of your brain to reorganize itself over your life due to your environment, behavior, and internal experiences. The concept of a changing brain has replaced the formerly held belief that the adult brain was pretty much a physiologically static organ or hard-wired, after critical developmental periods in childhood. While it’s true that your brain is much more plastic during childhood and capacity declines with age, plasticity happens throughout your life.

Neuroplasticity is the process through which all learning and memory happen. In fact, your brain even has to learn how to learn. A lot of the time, neuroplastic change is happening below your conscious awareness, and it can help or hurt you. It’s because of neuroplastic changes that addictions and some major brain illnesses and conditions show up in humans. However, neuroplasticity also allows recovery from brain injury, addictions, and many mental health conditions.

Because of neuroplasticity, you are not stuck with the brain you’re born with or that you have at any given time in your life. If you make the effort to intentionally guide neuroplastic change, you can improve your brain and mental health. For a thorough explanation of how plasticity physically happens in your brain, see Masterpiece Or Mess.

Building Baby’s Brain

A human baby is born with a staggering amount of neurons — somewhere around 100 billion — but they’re not connected yet. Like all mammals, our brains come “assembly required” — like a super deluxe Lego set. Billions of tiny pieces are there, and the possibilities are endless, but it’s going to take a lot of time to put them together. As little people grow and interact with others and the world, connections are wired in their brains based on their experiences. Life sculpts their brains through neuroplasticity by the way of electrical impulses.

In his book, Soft-Wired: How the New Science of Brain Plasticity Can Change Your Life, Dr. Michael Merzenich a leading pioneer in brain plasticity research and co-founder of Posit Science, explains a baby’s brain like this:

"You can imagine a newborn’s brain like a highway map of North America or Europe or Asia with just the largest freeways and most important highways laid onto the map. Those major thruways interconnect regions to one another — but no one has yet constructed any local highways, secondary roads, streets, byways, lanes, driveways, or garden paths. Most places (specific abilities) remain inaccessible until these routes are in place!”

A baby’s brain has almost no ability to regulate brain change. This is why emotional and attachment experiences in infancy have such lasting impact. Almost any experience changes their brain. As a baby begins to learn to control their selective attention, their brain also gradually learns to control brain change.

Neuroplastic Change Is Culturally Specific

In this early critical period, an infant’s brain processing machinery begins to develop and specialize according to the specific world in which it was born. For example, babies born in different cultures learn to control the parts of their body used to speak in ways that are specific to their language. This is accomplished by the sculpting of neural networks, through neuroplasticity, to fashion the special machinery needed to produce and receive the sounds of their native language. Studies show that at the age of six months, a Japanese baby can hear the English “r-l” sound distinction. At one year old, they no longer can distinguish between the sounds because of massive rewiring and pruning of cortical real estate that has taken place over the prior six months in their brains specific to their language.

Plasticity Becomes More Selective 

Over time, as a child moves, behaves, feels, speaks, and thinks and the world responds with some predictability, the default pathways in their brain begin to become more coordinated and efficient. The plasticity processes competitively sort out the responses evoked in their environments and uniquely sculpt their brain accordingly. Eventually, neuronal pathways create a reliable representation of the world in which they live.

The early “anything goes” and “always-on” plasticity period comes to an end. The brain undergoes physical and chemical changes that increase the power of the plasticity “off” switch, and it begins to dominate. In other words, their brain increasingly only allows change to occur when it determines, according to its own standards, that it is important and wants to change. Merzenich writes:

"From the end of this critical period forward to the end of life, the brain controls its own self develop — its plasticity. It no longer absorbs everything it hears, sees, and feels. This is a good thing. If the adult brain made enduring plastic changes based on everything it sensed, certain experiences would become grossly and highly inappropriately represented in the brain. As an example, since most of us spend a lot of time sitting down, an enormous area of our brains would become dedicated to information from our fannies, which isn’t exactly the best possible use of our brain resources!”

In her book, Habits Of A Happy Brain, Loretta Graziano Breuning, Ph.D., explains how experiences change a child’s brain.

Experience insulates young neurons.

As a neuron gets used more often, it develops a fatty coating called myelin. Myelin helps neurons to conduct electricity more efficiently. Much of your myelin is produced by the age of two, tapers off around seven, and ramps up again at puberty.

Repetition makes a synapse more efficient.

A synapse is a space between two neurons. An electrical signal can only jump the space to keep moving in your brain if it has enough oomph when it reaches the synapse. These synapse breaks help your brain filter out important input from noise. Anything deemed not worthy doesn’t make it across the synapse, and anything tagged significant keeps going.

A synapse develops in two ways: repetition and emotion. Repetition develops a synapse gradually. If a synapse is activated enough times, it learns to carry signals efficiently. Emotion can develop a synapse instantly. In your brain, emotions are chemical molecules that can change a synapse immediately and permanently.

Only neurons that are used survive.

Like we learned earlier, the human brain has billions of neurons at birth. Neurons that aren’t used begin to wither in a process called synaptic pruning. Pruning actually increases intelligence and helps a child stay focused and alert instead of attending to everything in their environment. Most pruning takes place between the ages of two and seven. Because of this, a child’s brain link’s new experiences later to relevant past experience instead of storing each new experience as an isolated chunk.

New synapses grow between neurons that get used.

Each neuron has multiple synapses on its many branches or dendrites. Electrical stimulation causes new dendrites to grow. As more dendrites grow in hubs of electrical activity, impulses are going to jump the gaps from one dendrite to another and new synapses are born. When the brain forms memories or learns new skills, it encodes the new information by tuning the connections between neurons. This is how the brain links ideas, thoughts, or concepts.

Emotion receptors grow or atrophy as needed.

For electricity to jump a synapse, the dendrite on one side has to release a neurochemical that arrives at a receptor on the other side. Each of our brain chemicals has a unique shape that only fits certain receptors. It’s similar to a key fitting a lock. When you feel a strong emotion, you’re releasing more chemicals than there are receptors for that emotion. So, your brain makes more.

Think of the implications of this in your life. If you don’t use your “happy” receptors, you lose them, and the more frequently you use your “sad” receptors, the more you have. In this way, depression, anxiety, and many other mental health conditions reinforce themselves in your brain.

Turning Plasticity Back On in the Adult Brain

In youth, your brain creates new circuits effortlessly. As an adult, new connections and patterns can be made throughout your life, but it requires more effort. (That’s why habits are so darn hard to break!) Understanding how your brain works and how experience alters it can help you intentionally remodel your circuits, change your behavior, and positively impact your life.

For a detailed explanation of these conditions, see Ten Fundamentals Of Rewiring Your Brain. In brief, the circumstances according to Dr. Merzenich in Soft-Wired: How the New Science of Brain Plasticity Can Change Your Life are when:

• you pay careful attention or focus on a task or a goal;
• your brain is rewarded or punished — or expects a reward or punishment;
• your brain positively evaluates your performance in goal-directed behavior;
• you are surprised — or threatened — by something new or unexpected.

Now that the brain has learned to control its neuroplastic brain-changing ability, it activates it by releasing modulatory neurotransmitters. Mr. Merzenich explains this with this example:

For instance, if you achieve a learning goal or feel successful, one of those modulatory neurotransmitters, dopamine, is released. It tells your brain ‘Save that one!’ If you are positively or negatively surprised, another neuromodulator, noradrenaline, pumps out to tell the brain ‘Wow!’ or ‘Watch out!’ If you are totally absorbed by a task, acetylcholine spritzing tells the brain to ‘Try this one!’ as it amplifies new options for changing the brain so that it can improve at the task. conversely, when a task or experiences are unimportant or routine, your brain doesn’t release these chemicals. The plasticity switch remains in the “OFF” position — and nothing changes in the brain.

For more specific information on self-directing neuroplastic brain change, see 4 Ways to Harness Neuroplasticity to Improve Your Brain.