An old saying goes that if we want to overcome fear, we have to face her. It seems to be true: scientists have obtained for the first time confirmed that, in the brain, the neural circuits in which memories of traumatic events are stored must be reactivated to ensure that fear diminishes.

Experts long debate on what are the neural mechanisms underlying the memory of the trauma, and how it is stored in the memory trace of these events. In particular, it is unknown whether the decrease in anxiety and fear linked to a memory occurs when the original memory fades, or if the starting time on the memory is overwritten it one that has gradually lost its menacing tinge.

Enlightened by fear. To study how they are stored and revived fearful memories, researchers at the Federal Institute of Technology Lausanne (EPFL) have used mice genetically modified so that, in their brain, a "label" Fluorescent lights up a set of neurons in the moment you They activated.

anxiety, psychology, phobias, fear, brain, remember, memory, hippocampus
In the brain of a mouse, a cell activated by the fearful stimulus (in green) superimposed on an activated by the recall of the same memory in a non-threatening situation (in red). | EPFL / Grff Group

In this way they were able to view a precise "engram," that is, the physical track in which the memory is preserved. The animals, in a plexiglass cage, were subjected to a mild shock to her leg. By observing which cells were activated, researchers have firstly identified the nervous circuit in which the memory was stored: a particular group of neurons in the so-called dentate gyrus of the hippocampus, a brain structure essential for memory. Even a month away, if put in the same cage, the animals are immobilized - a clear sign of fear in these animals - proving to remember the shock, while the brain is lit the corresponding neurons.

Relive the memories. The mice, at that point, were subjected to a kind of therapy to weaken the scary memory, similar to those cognitive-behavioral which trauma victims who are subjected, in a controlled manner, reminiscent of the situation or the object that has caused the trauma. In a gradual manner, usually the level of anxiety and fear decreases. In the case of mice, the animals were again placed in the same box in which they received the shock, but no requirement was administered. Slowly, the animals began to not fear it anymore.

Looking at what was happening in their brains, the researchers saw that in action were still the same neurons before. Not only the mice had less fear, more cells were active. As if researchers intervened "turning off" neurons, he fear not diminished.

anti-fear therapies. In essence, the researchers conclude in the article published in Science, the group of neurons responsible storage of fearful memories is the same that is activated when the memory is weakened. Even more, the reactivation of the fearful memory seems indispensable condition because fear wears off. It would be short, the physical trace of memory to change, losing its scary connotations, in favor of the more reassuring.

The study confirms what many therapists basically know, and that is that the fear must be addressed and relived to be overcome. And, in addition, the identification of the nervous mechanism underlying this effect could lead to future treatments to treat anxiety and pathological fear, such as post-traumatic stress disorder.

From Focus