By Catherine A. Sanderson, Amherst College
The brain can change in response to environmental factors and experiences. This finding that the brain forms new connections and makes new pathways in response to life experiences has tremendous practical implications. Another equally important finding is that the brain also gets rid of old, useless pathways. These factors together influence brain development.
The Brain’s Ability to Reorganize
When blind people learn to read Braille using their fingers, the part of the brain dedicated to processing touch—the parietal lobe—expands. Similarly, string musicians who first start playing their instrument in childhood, when brain reorganization can happen more easily, have larger and more complex neural pathways linked to the fingers on their left hand, which controls the notes they play, than those whose music training started later in life.
Thus, the brain has the ability to reorganize in response to daily life experiences.
This finding that the brain forms new connections and makes new pathways in response to life experiences has tremendous practical implications. Researchers at MIT found that young children who have more back-and-forth conversations with adults show much more activation in Broca’s area—the part of the brain that is involved in speech production and language processing—when they listen to stories. This greater brain activation fully predicts children’s scores on tests of language skills, including vocabulary, grammar, and verbal reasoning.
This article comes directly from content in the video series Introduction to Psychology. Watch it now, on Wondrium.
Getting Rid of Irrelevant Pathways
It’s certainly an important finding that new life experiences create new pathways in the brain. But, there’s another equally important finding, that the brain also gets rid of old, useless pathways. Getting rid of irrelevant pathways is as important a part of brain development as forming new ones.
From the moment of birth, a baby’s brain is constantly changing and developing, as it’s flooded with new sensory information. Each new experience a child has—learning a new word, seeing the ocean for the first time, meeting a new person—has to be sent to the brain so that it can be processed, which leads to changes in brain structure, function, or both.
As each brain cell matures, it forms more and more neural connections with other brain cells, which is why babies add more than a million new neural connections every second. This process leads to rapid brain growth during the first few years of life.
At birth, each neuron in the cerebral cortex has about 2,500 connections. But two or three years later, each neuron has about 15,000 connections and that’s about twice as many neural connections as the average adult brain! This is far, far more connections than the brain needs and makes processing information slow and inefficient.
Between early childhood and adulthood, a natural process known as synaptic pruning takes place in which the brain basically decides which connections are important to keep, and which ones can be let go. Connections that are regularly activated are maintained because the brain gets that they are obviously important. But weaker connections, those that are rarely called upon, are slowly pruned away.
Settling in Structure
So, the brain is basically getting more settled in its structure during adolescence, as children transition into adulthood. This natural maturation process allows for more complex thought processes and more sustained attention. But it also shuts certain doors.
The brain becomes less flexible as neural connections are pruned away. So, if a child experiences a brain injury at age 10, another part of the brain can take over the functions of the part that is damaged. If this same injury occurs at age 20, that shift is no longer possible.
This pruning process also explains why it’s almost impossible to learn to speak a new language without an accent as an adult, or even as a teenager. If children use their brain for only one language, during their first few years of life, the neural connections that would allow them to easily learn a second, or third, language are pruned away, which is why teenagers and adults learn languages much more slowly and less efficiently than small kids.
Factors Influencing Brain Development
All of the different parts of the brain and their distinct, and sometimes overlapping, functions come together with life experiences—playing an instrument, learning a new language—to influence brain development.
And so, one of the most intriguing questions in the field of neuroscience is how much our brains influence our behavior versus how much our behavior is influencing our brains.
Here’s an example: people who are especially attuned to social conflict and care more about fitting in with the crowd also have a larger orbitofrontal cortex. For these people, feeling different feels really bad. For other people, this region of the prefrontal cortex is smaller, and fitting in may not matter as much, which makes it easier for them to stand up to social pressure.
So, are some people born with a larger orbitofrontal cortex? Or does resisting social pressure over time cause this region to increase in size? Or perhaps it’s both. What research tells us so far is that individual differences in such things as the ability to stand up to social influence can be mapped out in the brain.
Common Questions about Impacts of Environmental Factors and Experiences on Brain Development
String musicians who first start playing their instrument in childhood, when brain reorganization can happen more easily, have larger and more complex neural pathways linked to the fingers on their left hand, which controls the notes they play, than those whose music training started later in life. Thus, the brain has the ability to reorganize in response to daily life experiences.
Between early childhood and adulthood, a natural process known as synaptic pruning takes place in which the brain basically decides which connections are important to keep, and which ones can be let go. Connections that are regularly activated are maintained because the brain gets that they are obviously important. But weaker connections, those that are rarely called upon, are slowly pruned away.
If children use their brain for only one language, during their first few years of life, the neural connections that would allow them to easily learn a second, or third, language are pruned away, which is why teenagers and adults learn languages much more slowly and less efficiently than small kids.
