Scientists suggest erasing negative memories to heal mental trauma. And, on the contrary, you can fight depression by introducing pleasant impressions. All these methods are associated with an active effect on the brain with drugs or implanted electrodes, it is very laborious and ethically questionable.
Forget not to be afraid
Late last year, Spanish researchers studied how various drugs used in general anesthesia work on the human brain. To do this, fifty volunteers who had planned operations under anesthesia were shown two videos with a negative event in the middle a week before the procedure. In the first, the boy was in a car accident, in the second - the criminals attacked the woman. The beginning and end of both stories were emotionally neutral.
Immediately before the operation, the participants in the experiment were reminded of the videos by showing a frame of one of them. This was followed by general anesthesia. Some volunteers were asked to recall the details of the stories an hour after they woke up, others a day later.
It turned out that the drug propofol, which was used for anesthesia, is able to erase negative traumatic memories. Participants who tried to tell about the story, which they discussed in detail on the eve of the operation, a day later could not remember the details of the unpleasant event that happened in the middle of it. They remembered the second video better. Most of the details were given by those who were interviewed an hour after the anesthesia ended. It turned out that the effect of the drug was noticeable only a day after its use.
The authors believe that propofol is ideal for treating PTSD, a severe mental condition common to combatants or abused people, and other serious disorders associated with unpleasant memories.
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For depression and stress
In 2014, Japanese neuroscientists made laboratory mice forget about their fear. First, the rodents were placed in a cage, where they were subjected to electric shocks. The animals were frightened and froze. At the same time, certain accumulations of nerve cells were activated in the hippocampus, a part of the brain involved in the mechanisms of emotion formation and the transformation of short-term memory into long-term memory. Scientists use laser pulses to turn off these neurons and put the mice back into a dangerous cage. The animals did not experience any fear, although their relatives from the control group, whose brains remained intact, continued to be afraid.
The results of such experiments were tried to be applied to the treatment of various neurodegenerative and psychological diseases in laboratory animals.
In a study by American scientists led by Nobel laureate Susumu Tonegawa, mice were shocked to understand which clusters of neurons were activated. After the rodents forgot about fear, getting into the cell, where they were previously exposed to the current, these neurons were activated. The animals recalled negative experiences and felt fear again.
A year later, the same team learned to bring laboratory mice out of depression, artificially evoking pleasant memories in their memory. The researchers allowed the males to spend some time with the females, while isolating the neural ensembles that were activated during the mating process. Then the rodents were placed in a special vice to restrict movement for ten days. Already at the end of the first week of imprisonment, the mice showed signs of depression - they refused sweet water and did not try to escape when they were held by the tail.
But if neuroscientists “turned on” the neurons associated with female memories, negative symptoms disappeared in a matter of minutes. With the regular activation of pleasant memories, the mice came out of the state of stress within a week. Interestingly, when depressed males were simply hooked up with females, they ignored them, and the condition of the rodents did not improve.
Don't trust yourself
French researchers forced the mice to remember something that didn't really exist. The sleeping rodent's brain was reprogrammed in such a way that it formed a whole chain of false memories and associations.
The fact is that the memory of animals, including humans, turns from short-term to long-term memory, mainly during sleep. Based on this, scientists created a computer algorithm that made it possible to link memories of the places visited by the rodent with specific sensations - pain, fear, or pleasure. To do this, two electrodes were stuck into the brain of the mouse: one in the hippocampus, the other in the center of reward (pleasure).
In the brain of mice, in the hippocampus, there are so-called "place neurons", which are activated as the animal moves through space. Scientists have correlated one of these neurons with a specific part of the cell in which the rodent lived. When this neuron was activated during sleep in the animal's brain, an electrode was triggered to stimulate the pleasure center. In this way, initially neutral memories of the place were associated with something positive. When they woke up, the reprogrammed mice preferred to spend most of their time in the part of the cell with which pleasure was now associated. This method did not work with awake animals.
The authors of the study admit that this approach can be used for experiments with point manipulations of human memory. But whether such a technique will be effective in humans, given the added complications of electrode transplantation and possible ethical concerns, is unknown.
Moreover, as British scientists have established, a person still copes with the formation of false memories without complex scientific devices. According to them, the first memories of most people are not real. After interviewing more than six thousand respondents, the researchers found that forty percent of early memories date from one to three years of age, when episodic memories are not yet formed. So, they are all fictional.
In addition, American experts have demonstrated that false memories can simply be instilled in a person. Subjects who visited Disneyland were shown a fake Disney video featuring Bugs Bunny the rabbit. After a while, they were asked to talk about their trip to the amusement park, and 16 percent of the volunteers were sure they had met Bugs Bunny at Disneyland. Meanwhile, this rabbit is a character of the Warner Brothers studio and could not be in Disneyland.
The authors of the work emphasize: all the memories of the cartoon character were emotionally colored and replete with details, which means that people considered false memories to be real.