Over the past couple of years, I have featured a few research results that try to paint a clearer picture in the nature versus nurture debate. Today, I give you some pretty convincing argument on the side of nurture, at least for one small part of the brain for a critical stage in childhood development.
For the first 15 years of your life (give or take a few), your brain is in a constant state of development. Neural pathways are forming, different regions are strengthening, existing connections fall away – and a lot of it depends on experiences. After puberty, your brain is still capable of changing, but much of its internal structure is more or less set.
Now, new research from the University of Wisconsin shows what growing up in a stressful environment can do to a human being. According to results from Jamie Hanson, a psychology graduate student, it has a noticeable detrimental effect on working memory.
With the help of professors Richard Davidson and Seth Pollak, Hanson worked with a group of children aged 9 to 14 and their parents. After extensive interviews to determine the levels of stress – both physical and emotional – experienced by the child throughout his or her life, they were set to a series of cognitive tests and brain scans.
Those who reported higher levels of stress performed noticeable worse on the battery of short-term memory tests, such as funding a token in a series of boxes. What’s more, brain scans revealed that the the anterior cingulate, a portion of the prefrontal cortex believed to play key roles in spatial working memory, took up less space for the stressed.
The scans also looked at changes in brain tissue known as white matter and gray matter. In the previously mentioned areas that varied in volume with stress, the white and gray matter volumes both lower.
White matter is like a telephone wire, making long-distance connections in the brain. Gray matter takes care of the processing by using the information transported by the white matter. Gray matter early in development appears to enable flexibility; children can play and excel at many different activities. But as kids age and specialize, gray matter thins. It begins to be “pruned” after puberty, while the amount of white matter grows into adulthood.
“For both gray and white matter, we actually see smaller volumes associated with high stress,” Hanson says. “Those kinds of effects across different kinds of tissue, those are the things we would like to study over longer periods of time. Understanding how these areas change can give you a better picture of whether this is just a delay in development or more lasting.”
Of course, there’s nothing that says that these changes are permanent. It could just be that the stressed children are a little behind their peers, and eventually will catch up.
But maybe they won’t.
So for all of you parents out there, try not to send your kids to dangerous space ships or anything like that.