I wrote in my last blog, “A tough nut to crack, on the other hand, is an everlasting memory binding the parties to one another.” There is a reason for that.
One of the most exciting scientific discoveries of the latest is on epigenetics. Epigenetics is the study of heritable changes in gene activity not caused by changes in the DNA.
Stress hormones seem to boost an epigenetic process either increasing or decreasing the expression of certain genes. Stress hormones change particular cells of the brain that help memories to be easier retained.
We need to be careful, though. The term stress is dangerously ambiguous. “Stress is a word that is as useful as a Visa card and as satisfying as a Coke. It’s non-commital and also non-commitable,” as Richard Shweder says. I’m talking of stress in a biological sense, the response of the sympathetic nervous system to some events, its attempts at reestablishing the lost homeostasis provoked by some intense event.
Being an evolutionary biologist, when contemplating a mechanism, I always ask: “What is the function of that? What is that good for? A mechanism can originate by chance (most do), but if it does not confer the individual some extra benefits as to survival and reproduction, it will not spread into the population.
Asking the right question is the first step to getting the right answer. Never be afraid to ask and reformulate your questions. At one point, you’ll have asked the question that will lead you to the right answer.
Why do unpleasant memories seem to stay with us longer than pleasant ones, sometimes even for the rest of our lives?
Situations of exceeding anxiety and stressful, intense experiences create unpleasant memories. It is important, if not crucial, to remember situations that might have hurt us seriously. It makes sense that the stress hormones should facilitate our retaining the memory of events occurring under stress.
Stress hormones do bind to the particular receptors in the brain that enhance the control of the epigenetic mechanisms involved in remembering and, hence, in learning. They do boost the epigenetic mechanisms that control the expression of the genes crucial for memory and learning.
Not all stress boosts learning. Too much stress produces the opposite effect. There is a difference between being stressed and stressed out. When we experience far too much stress, our organism goes into alarm mode where survival has the first and sole priority and memory formation decreases. Chronic stress does not promote learning either.
Bottom line: we need to be nuanced about stress. Events causing healthy stress responses are necessary for enhancing attention to details, the formation of memory, creation of bonds, and learning—and too much stress, or for too long a period, works against it.