We like to think we’re so evolved because we live in such an advanced society. But really our society has grown faster than our brains can keep up. Our brain is like Lindsay Lohan, successful at a young age, having access to a million different opportunities before she’s ready for the responsibility, and, well, let’s say it caused some problems. In this post I’m just going to focus on one feature of modern society and its effect on the prefrontal cortex: loud noises.
Noise causes stress, and the prefrontal cortex is perhaps the brain region most susceptible to stress. One study in monkeys illustrates just how loud noises affect the prefrontal cortex. The researchers played loud noises to the monkey at an intensity somewhere between a jackhammer and a rock band (don’t you think “Jackhammer” would be a good name for a rock band?). They found that the monkeys were impaired only on certain tasks that involved working memory. Working memory is a fancy word for the type of thing you have to do when you have to remember a phone number long enough to write it down. If you’ve ever gone to the supermarket and forgotten the one thing you needed to buy, then you had a breakdown in working memory. Working memory utilizes the prefrontal cortex (more specifically the dorsolateral prefrontal cortex for those of you keeping score at home).
When stressed, the monkeys were perfectly good at doing tasks that did not require them to use working memory, but the loud noises caused them to make mistakes in working memory. Just to be clear, the noises were not played while they were doing the task, but beforehand. The residual stress from the noise messed up the proper functioning of their prefrontal cortex.
Now maybe that’s just a problem for monkeys, but other research shows that it’s a problem for us too. Some researchers in Germany took two groups of fourth graders who were matched on socioeconomic status (to each other, not to the monkeys). Some of the kids just happened to live near the Munich airport, while others lived in quieter neighborhoods. They did a bunch of testing on these kids, and found that the kids who lived by the noisy airport did slightly worse on some measures of working memory. However, the groups showed the same cognitive abilities. Also interesting, the kids from the noisy neighborhood had slightly higher blood pressure, suggestive of higher stress. They also had worse reading scores, and gave up more easily when trying to solve a difficult puzzle (as a sidenote, the puzzle was technically impossible).
While there is not a ton of direct evidence in humans about noise causing stress and problems in working memory, there is more evidence that noise causes stress, and also other evidence that stress causes working memory problems. So what can you do about it? Move somewhere quieter. That might sound silly, but part of the problem with loud noises is the inescapability factor. If you feel you have control over it, then it’s likely to not cause stress. For example, going to see your favorite band is probably a lot less stressful than being woken up by the road maintenance crew outside, even if they were equivalently noisy. And if you can’t physically move to a different environment, then just put on your headphones and let the smooth sounds of Kenny G carry you away.