Results of a new mice experiment study were revealed: wiping a memory from the brain is not only possible, but also specific memories can be weakened or even strengthened! The latest research from a plethora of studies was looking at ways to erase unpleasant memories, with help from previous work – studies that experimented with techniques ranging from brain scans and AI to the use of drugs to influence the brain in various ways.
Methods to erase memories of fear were tested on mice, with certain sounds being set to trigger alarming memories. The interesting thing is the pinpointing of a memory on a physical location – researchers say the findings could be used to either weaken or strengthen particular memories while leaving others unchanged.
This is a big step and could potentially be used to help those with cognitive decline or PTSD without damaging other memories, altering their personality through drugs etc:
“We can use same approach to selectively manipulate only the pathological fear memory while preserving all other adaptive fear memories which are necessary for our daily lives,” said Jun-Hyeong Cho, co-author of the research from the University of California, Riverside.
The journal Neuron hosted their study – they used genetically modified mice to examine the paths in the brain involved in processing a particular sound and the area involved in emotion-related memory functions. It was revealed that even after fear extinction, the neural pathways remained altered in the mice. This confirms that the brain can indeed behave in a plastic instead of an elastic way, without reverting to its previous state. But it’s worth noting that the memory is not entirely erased, just merely locked away:
“These mice are special in that we can label or tag specific pathways that convey certain signals to the amygdala, so that we can identify which pathways are really modified as the mice learn to fear a particular sound. It is like a bundle of phone lines,” he added. “Each phone line conveys certain auditory information to the amygdala.”
“Fear extinction is not an eraser of fear memory ,” said Cho. “It just hides the fear memory transiently.”
They soon discovered that by using a technique called optogenetics, it was possible to truly erase the unpleasant memories. This technique involved the researchers using a virus to introduce genes into particular neurons in the brains of the mice that were involved in the “high-pitch” pathways. Once inside the cells, the genes result in the production of proteins which respond to light, allowing researchers to control the activity of the neurons.
Taking mice with the fearful memories, the team exposed the neurons involved in the “high-pitch” pathway to low-frequency light – an approach which weakens the connections between the neurons. The upshot was that the mice no longer appeared fearful when they heard the high-pitched tone.
“It permanently erases the fear memory,” said Cho. “We no longer see the relapse of fear.”
Peter Giese, professor of neurobiology of mental health at King’s College London, said it was too soon to think of using the research to help those with psychopathologies, saying it would be unethical to use optogenetic techniques on people. “Exactly how this can be applied to humans is a little bit unclear to me,” he said.
Nevertheless, Giese said the study was a big advance, not only in improving understanding of fear extinction, but also highlighting the importance of the strengthening of connections between neurons in forming memories. What’s more, he said, it reveals a way to reverse the process.