If you have always been stressed about driving and you get into a minor accident while driving, that event will create a bad memory in your memory. Later, when you try to get into a car, that memory will resurface to make you afraid. The accident that did not put your life at risk triggered unjustified Post-Traumatic Stress Syndrome. From that moment on, you will avoid driving without realizing it. This scenario can be repeated in any daily activity.
The link between stress and unjustified fear is widely accepted. However, since the act of fear is a multifactorial phenomenon, it is not possible to point to a single origin. A recent scientific study seems to have found the neurological mechanism that alters memory and encourages the appearance of anxiety after a stressful event.
According to a publication in cellsstress disrupts the way bad memories are built. Substances released by stressed bodies “intensify” memories linked to fear, expanding their size to hold more than they should. In other words, a stressed person becomes more susceptible to linking negative memories with neutral ones and reacting aversively to both.
The bricks that form bad memories
Any memory is physically stored in the brain in the form of engrams. Depending on the type of memory, it will be stored in one part or another of the brain. For example, the memory of riding a bicycle, a motor skill, is associated with the cerebellar region, while traumatic episodes are stored between the amygdala and the hippocampus.
Engrams are considered graphic representations of memories, but they are far from being sets of neurons located at a single point. Neuroscientists propose that they be imagined as specific footprints or trails in a field with thousands of paths. When a person plays a musical instrument from memory, their brain is actually following a single path or engram to execute the movement perfectly.
With traumatic memories it works in a similar way. After a life-threatening bad moment, the brain activates the amygdala and creates a warning engram. This path will be traveled when a person returns to the scenario that initially created the frightening experience.
Stress can cause neutral scenarios to become part of a fear engram near the amygdala. To find out, scientists experimented with mice. First they stressed them out, then they created bad memories in them, and finally they reviewed their neural activity, as well as their behavior in out-of-danger scenarios. Stressed rodents had a larger engram than relaxed ones. Therefore, they reacted with fear in dangerous circumstances and in common scenarios.
The key to the process is a chemical regulator in the neuronal behavior of the engram called gamma-aminobutyric acid (GABA). In the words of the researchers themselves, “it works like the velvet rope of a nightclub. “It only lets certain neurons into the club.” However, under stress, the body pumps out a neurotransmitter that prevents the release of GABA. “In other words, the safety net drops and many neurons can enter that exclusive club,” says Sheena Josselyn, co-author of the study. The engram is limited by GABA, but if the memory is formed under stress, then the memory more than it should
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