Neuron: the memory of fear can be erased permanently
A mouse study has revealed a new way to erase memories in the brain, and the results suggest that specific memories can be strengthened or weakened.
Scientists say humans are a step closer to having a pure, sunny mind.
A recent study in mice has revealed that particular sounds can stir up fear memories and implement a new way to remove that memory from the brain.
The findings could be used to strengthen or weaken specific memories without affecting other memories, the researchers said.
This, they say, can help patients with cognitive decline or post-traumatic stress disorder, removing their fear memories (such as dog bark) without affecting useful memories.
Research collaborators at the university of California, riverside, Jun - Hyeong Cho said: "we can use the same methods to selectively to deal with morbid fear memories, only and will not affect other adaptive fear memory, because the memory is helpful to our daily lives."
Study of its kind in the past, scientists have tried a variety of technologies, including brain scans, artificial intelligence, drug use, as well as the realization in mammals such as external decode of associative memory.
The study is the latest.
The study, published in the recent issue of the Neuron, was completed by Cho and his colleague Woong Bin Kim.
The team used genetically modified mice to test pathways between two brain regions, regions that deal with specific sounds and regions associated with emotional memory (the amygdala).
Cho said: "we can look at the specific signal transmission to the access of the amygdala, so can determine when mice learn to fear to a particular voice which path is changed.
It's like a bunch of phone lines, and every phone line sends a specific message to the amygdala."
In the first part of the lab, the team asked mice to listen to the sounds of high-pitched and low-pitched sounds.
But when the high-pitched voice sounded, the researchers gave the mice a mild electric shock.
When the high pitch sounds again, the mice are frightened, and when they hear low tones, they don't.
The researchers then analyzed whether there was a difference in the pathways between the sounds of high-pitched and low-pitched voices into the brains of mice.
The results showed that high-pitch pathways were more strongly associated with the mice that were shocked, while the lower ones did not change.
The team found that if the mice were to repeat the high-pitched sound without being shocked, the fear would disappear, a process known as fear extinction.
"Fear extinction is the psychological basis of exposure therapy, which is used to treat post-traumatic stress disorder," Cho said.
But after exposure therapy, for example, two weeks, the fear will spontaneously appear again.
He added: "this new study offers an explanation: even after the fear has subsided, the neural pathways in the mouse's high pitch are still strong.
Fear subsides not to eliminate the memory of fear, but to hide it temporarily.
But the team found that using optogenetics could actually remove unpleasant memories.
The researchers used a virus to inject genes into specific neurons in the mice's brains.
Once the genes into the cells, they can generate photosensitive protein (in the life can reply optical signals and produce physiological reaction of protein), allowing researchers to control the activities of the neurons.
The researchers exposed the neurons associated with the "high-pitch" pathway to low-frequency light, which can weaken the connections between neurons.
As a result, the mice no longer felt fear when they heard high tones.
At king's college London, says Peter Giese neurobiology professor will the method used to help psychiatric patients for now it is too early, it is immoral to light genetics technique is applied to human.
"I don't know how to use this method for humans," he said.
However, Giese acknowledges that the study is a huge step forward, not only reinforcing the understanding of the extinction of fear, but also stressing the importance of strengthening neuronal connections in memory formation.
In addition, the study showed a way to reverse the process of memory.
"It really can be said to delete memories," he said.