Aside from taxes and death, there is another matter that none of us could escape — stress. But are all stresses the same?
As far as the brain is concerned, there are two kinds of stresses, one chronic and one acute. Chronic ones are the ones that happen regularly over a long period of time. That kind of stress takes a toll on our system, not the least of all on our memory and learning. But for situations that suddenly confront us which we rely on our working memory for, there is the acute kind of stress that seizes us only temporarily and it enables us to think more creatively and perform better. This has been observed in our behavior. Now, scientists know a little bit more of how this happens in our brains.
We know this from a very recent study entitled Acute stress enhances glutamatergic transmission in prefrontal cortex and facilitates working memory published in the early edition of the Proceedings of the National Academy of Sciences. The researchers were Eunice Y. Yuen, Wenhua Liu, Ilia N. Karatsoreos, Jian Feng, Bruce S. McEwen, and Zhen Yan.
When we are stressed, we produce hormones called cortisol. These hormones affect our brain cells through receptors in the brain. The scientists looked at the prefrontal cortex (PFC) which is the region in the brain that seems to get very activated when we experience stress. PFC is also the region that encases how we think and feel. They found that when moderate doses of cortisol get to meet up with certain receptors in the brain, the neurons in PFC become moderately excited and this kind of excitement translated into actions makes us perform better. But before you go about welcoming and embracing all kinds of stresses, you should know that previous studies have shown that in cases of repeated serious stress across long periods (chronic), the result is the opposite, and in some, mental disorders.
Before science was able to peer inside brains, studies have confirmed it in our behavior. When we get stressed in the form of surprise or fear, we suddenly are able to summon the quick response necessary to deal with the situation. This is called “fight or flee response” which could sometimes determine whether we live or die. But this experiment found that moderate amounts of cortisol, which are released in moments of acute stress, are responsible for this quick mental draw.
Since it is unethical to subject humans to real acute stresses, the researchers did the experiment on rats. If you can read this column, you are not a rat but you will be surprised how much you share with rats. In fact, most treatments and cures for spinal cord injuries of humans have relied on experiments with rats. The recent report on the blue artificial color in Gatorade and M&Ms being able to treat secondary spinal cord injuries is proof of this, especially if you do not mind turning blue as a side effect. In fact, nine out of 10 genes between humans and rats are similar. A good 90 percent of lab studies are on rats and their cousins — mice. There is a very high chance that any of the drugs that you are taking now first were taken by rats or mice which did not volunteer for those tests but which ended up being tested anyway.
Another reason why the study was done on rats is the kinds of stresses this experiment did to rats. If this were done to humans, this will be among the headlines grabbing the news. The experiment subjected the rats to three kinds of stress: they were forced to swim for 20 minutes; they were kept in such a cramped space for 20 minutes where they were rendered almost immobile; or they were put on a raised platform for 20 minutes. Then, they were asked to perform a learning test by running the classic maze shaped like a T. It turned out that the rats that underwent acute stresses performed much better than those that were not subjected to the stresses.
These are probably not the kind of modern stresses that humans confront but this gives us a picture of what “stress” looks like in terms of how our brain works. It is clear that cortisol has to do with being able to have a better working memory. And since cortisol is a hormone released in times of stress, it is also clear that stress is a necessary part of living. So the next time you get bored and cannot move on, try to find the stress nearest you. Living in Metro Manila, I am sure it will not be too hard to find one.
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