Stress rebuilds the brain and enhances emotional memories

To find out, the researchers conducted an experiment with volunteers who took a capsule twice, on different days, either with hydrocortisone or with a placebo. After taking the pill, the participants watched a series of images in an fMRI machine and assessed their emotions — how much each image aroused or disturbed. The next day, we checked which pictures the person could remember. Neither the participants themselves nor the experimenters knew which drug had been taken.

A special analysis of the fMRI data provided the key to the discovery. Instead of the standard long recordings of brain activity, the team analyzed how the interaction of brain regions changed within just a few seconds — during each individual image. Such actions allowed us to see individual fragments of emotions and memory and understand how cortisol changes their work.

According to the results, cortisol actually enhanced the memorization of emotionally intense images. At the same time, the hormone made the networks responsible for the perception of emotions more stable and active, and the networks associated with memory more attuned to emotional content. In addition, coordination between these systems was enhanced, so that emotional events were recorded especially firmly.

According to the lead author of the study, Elizabeth Goldfarb, a stress reaction in itself is not harmful — on the contrary, it helps us to better remember important and significant events if they have an emotional charge. This explains why we remember many vivid, dramatic, or frightening moments for years, while neutral events fade after a few days.

It is noted that data can be useful in learning: if a person is under stress and trying to learn new information, it can help them focus on emotionally significant or fascinating elements of the topic. At such moments, the brain literally amplifies everything related to emotions and rebuilds its work to make these memories more durable.