Yale scientists discover how cortisol strengthens emotional memories — ScienceDaily

Researchers at Yale University have found that the stress hormone cortisol can strengthen memory of emotionally significant events by altering the functioning and interaction of brain networks associated with emotions and memory formation. The findings were published in the journal Science Advances, ScienceDaily reports.

In the study, participants completed the experiment twice: once after taking hydrocortisone, a form of cortisol, and another time after taking a placebo. During functional magnetic resonance imaging, they viewed a series of images and rated their own emotional response to them. The following day, researchers tested how well the participants remembered what they had seen.

Analysis of brief brain signals

The experiment had a double-blind design: neither the participants nor the experimenter knew which substance had been taken during a particular session. This made it possible to compare the brain responses of the same person with and without the additional effect of cortisol.

The team analyzed functional connectivity in the brain — coordinated fluctuations in the activity of different regions. Such analysis usually requires data collected over several minutes. In this study, researchers assessed connections between brain regions within individual episodes lasting about five seconds.

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This approach made it possible to separately identify patterns of brain activity associated with the intensity of the emotional response to an image and with whether a person would be able to recall it the following day.

Interaction between emotion and memory

The study confirmed previous findings: cortisol improved the retention of emotionally significant events. In emotion-related networks, the hormone promoted more consistent patterns of activity and increased their engagement.

In memory networks, cortisol made activity patterns more specialized for emotional information. It also strengthened coordination between brain systems that process emotions and encode memories. According to the authors, stress does not improve memory for everything equally, but can selectively enhance the retention of experiences that a person considers emotionally intense or significant.