Researchers from the Canadian Hospital for Sick Children discovered that stress changes the way our brain stores and retrieves unpleasant memories, and the research team, in cooperation with researchers from the Hotchkiss Brain Institute at the University of Calgary in Canada, was able to find a way to deal with them.
If you stumble during a presentation, you may feel nervous the next time you have to give a presentation; This is because your brain associates your next presentation with that bad and unpleasant experience, and this type of stress is associated with a single memory. But stress caused by traumatic events such as violence or generalized anxiety disorder can spread beyond the original event, known as stress-induced aversive memory generalization, as fireworks or car sounds can trigger frightening memories that may relate to war or other events. Non-fireworks related violence. In the case of PTSD, this can cause much greater negative consequences.
Post-traumatic stress disorder develops in some people who have been exposed to a traumatic, frightening, or dangerous event, as it is normal to feel fear during and after a traumatic situation. Fear is part of the body’s “fight or flight” response, which helps us avoid potential danger or respond to it. Some people may experience a range of reactions after trauma, and most people recover from symptoms over time. But those who continue to experience fear may be diagnosed with post-traumatic stress disorder, as remembering the event causes them to relive it, including its physical symptoms, such as a racing heart or sweating.
Generalized aversive memory
Researchers Sheena Joslin and Paul Frankland, senior scientists in the Neuroscience and Mental Health Program, conducted research into the biological processes behind stress-induced aversive memory generalization, highlighting an intervention that could help restore the specificity of memory for the associated incident for people with the disorder. After the shock.
“A little stress is good, it’s what gets you up in the morning when your alarm goes off, but too much stress can be debilitating,” Jocelyn says, according to Eurek Alert. “We know that people with PTSD show fear in situations or environments that “Don’t call it that, and we’ve found a way to reduce that fear and reduce the potentially harmful effects of PTSD.”
Stress-induced memory generalization
Similar to the way PTSD occurs in humans, the research team exposed mice to an acute, but safe, stressor before something unpleasant happened to create a fearful memory in the mice, but it is non-specific and can emerge when ordinary situations occur that are not related to the upsetting event.
The team then examined long-term physical changes in the brains of mice that encode these subject-specific memories, or what are known as “engrams,” which are physical representations of a memory in the brain, created by the Joslin and Frankland laboratories at the Hospital for Sick Children. Engrams usually consist of a small number of neurons, but stress-induced memory engrams involved a much larger number of neurons, and these larger engrams produced generalized fearful memories that were retrieved even in non-fearful situations.
When the team looked more closely at these large engrams, they found that stress caused an increase in endocannabinoids, disrupting the function of mesenchymal neurons, whose role is to restrict the size of the engrams.
An engram is a physical representation of a memory in the brain. In other words, it is the physical effect that the memory leaves on the structure of the brain and the connections of its neurons. The engram is formed when the brain stores information about a specific experience, whether positive or negative, and this information is encoded in the form Changes in the strength of connections between neurons in different areas of the brain.
Endocannabinoids are natural chemicals produced by the body, similar in structure to cannabinol found in the cannabis plant. These substances play an important role in regulating many vital functions in the body, including pain, mood, appetite, and memory.
Memory and the endocannabinoid system
The endocannabinoid system enhances memory formation and helps link lived experiences to specific behavioral outcomes. The amygdala, the emotional processing center in the brain, contains special receptors for endocannabinoids, but when too many endocannabinoids are released, the function of the guard neurons is disrupted. Which causes the engram to increase in size.
“By blocking just these endocannabinoid receptors on these specific intermediate neurons, we can essentially prevent one of the most disabling symptoms of PTSD,” Jocelyn explains.
A surprising link between stress and the developing brain
In 2023, previous research in the journal Science identified larger, more general memory engrams in the developing brain compared to the adult brain, just like stress-induced memory engrams. While scientists continue to explore this unexpected link between engram size, stress, and age, research is also delving into how The effect of daily stress on happy memories.
“The many biological functions and processes that make up the complexity of human memory are still being studied, and we hope that as we better understand human memory, we can guide those with various psychiatric and brain disorders throughout their lives to real-life treatments,” Frankland says.