Scientists in the United States have discovered that certain sounds can trigger disturbing memories, and this discovery has helped to find a new approach to erasing unpleasant memories from the brain. The study was published in the journal Neuron.
The researchers studied the region of the brain of genetically modified mice associated with sound processing (hippocampus) and the region responsible for emotional memories (amygdala). The researchers were able to mark neural channels in the rodent brain that carry signals to the amygdala. This helped to determine through which channels the sounds that mice are afraid of are transmitted. One of the study authors compared this approach to telephone lines, each of which transmits specific information to the amygdala.
In the first part of the experiment, the scientists turned on high-frequency and low-frequency sounds for mice. Simultaneously with the first type of signal, the rodents were electrocuted. Later, the mice, hearing this sound, did not move due to fear.
The scientists went on to compare how the brains of mice respond to high-frequency and low-frequency sounds. It turned out that the channel through which the first signal was transmitted to rodents, who were beaten with electric current, strengthened. The other channel remained unchanged.
During the last stage of the experiment, the researchers turned on high-frequency signals to the same rodents without physical influence, and after a while the mice ceased to be afraid, but the neural channel did not return to its original state.
The author of the study commented: “Fear relief is the mainstay of psychological therapy aimed at treating post-traumatic stress disorder. Nevertheless, after a two-week course, a relapse may occur and the feeling of fear will arise again."
Scientists were able to get rid of the memories of fear with the help of optogenetics. To do this, they injected a virus into the neurons of the channel that transmits high-frequency sounds. With its help, the researchers controlled the activity of these neurons - a protein that responds to light began to form inside the cell. Thus, the scientists managed to weaken the connections between the neurons of the channel through which the "terrible" sound came, and after a while the mice were no longer afraid of it.
Researchers believe it is too early to test the technology in people suffering from PTSD, but this discovery is a big step in finding ways to get rid of unpleasant memories.
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