Researchers at Yale University have discovered how stress reinforces memories, finding that the hormone cortisol connects brain networks responsible for emotion and memory.
A brain scanning trial revealed that the stress hormone does not act on a single region of the brain, but instead synchronises the response between perceived intensity and long-term memory recording.
Cognitive neuroscientist Elizabeth Goldfarb, an assistant professor of psychiatry at the Yale School of Medicine and of psychology at the Yale Faculty of Arts and Sciences, led the study published in the journal Science Advances.
Stress is widely regarded as a harmful element, and cortisol is commonly known as the stress hormone. Beyond its connection to stress, cortisol plays essential roles in metabolic regulation, glucose control, and maintaining blood pressure.
While people frequently associate stress with memory lapses and poor concentration, the findings from Yale point to a direct relationship between intense emotional moments and clearer memory formation.
Neural networks and emotional memory
The ability to lock in detailed memories does not apply to every moment equally. Instead, the process focuses specifically on experiences carrying a heavier emotional load.
Cortisol affects two distinct and complementary neural networks in the brain. The hormone acts dynamically to evaluate situations of emotional intensity while simultaneously influencing the memory storage process.
To examine the mechanism, researchers conducted a double-blind trial where participants were administered hydrocortisone, a medication that mimics cortisol, or a placebo before viewing images inside a functional magnetic resonance imaging scanner.
Functional magnetic resonance imaging, or fMRI, allows scientists to measure brain activity by detecting changes in blood flow while participants complete tasks.
Researchers analyzed functional connectivity in five-second blocks per image to determine if brain activity patterns predicted perceived emotional intensity and the ability to recall the image the next day.
Brain synchronisation and memory consolidation
Scientists already knew that stress could consolidate memories based on prior experiments with humans and rodents. However, the precise connection between memory and the emotional experience itself remained unclear until this trial.
Goldfarb explained that the formation of memories from emotional experiences involves different processes in the brain, starting with perceiving an experience as emotional or intense and then encoding that experience into long-term memory.
In participants who received hydrocortisone, researchers observed that the hormone caused the emotional network to activate with greater intensity and consistency.
At the same time, the memory network specialized in emotional content, demonstrating that cortisol increased the joint synchronisation of both brain structures.
The research team validated their hypothesis that cortisol influenced not only the emotional intensity triggered by an image, but also the lasting memory generated to be recalled the following day.
Adaptive nature of stress responses
The findings indicate that the widespread belief that stress only harms memory must be re-evaluated. Reaching beyond negative perceptions, stress reactions facilitate adaptive responses that help individuals adjust to their environment.
Together with cortisol, these reactions enable the brain to establish firmer memories when dealing with episodes that carry a high emotional charge.
Goldfarb noted that stress responses are fundamentally adaptive and can help form solid memories, although this applies specifically to experiences that an individual considers emotionally intense or meaningful.
Yale University, located in New Haven, Connecticut, conducted the study as part of ongoing cognitive neuroscience research. The complete findings were peer-reviewed and published in Science Advances.
