Mice cured of retrograde amnesia
Biologists have learned how to restore lost memory
Japanese scientists were able to cure mice of amnesia by restoring lost memories with the help of light. A new study has helped resolve a long-standing dispute among neurophysiologists about the nature of memory: retrograde amnesia (associated with injuries and Alzheimer's disease) is apparently caused not by irreparable damage to brain cells, but only by blocking access to intact memory. The biologists told about their experiments on the pages of the journal Science (Ryan et al., Engram cells retain memory under retrograde amnesia).
A team of scientists led by Nobel Prize winner in Medicine (1987, "For the discovery of the genetic principle for generating a variety of antibodies" – VM) Suzumi Tonegawa (Susumu Tonegawa) wanted to find out if it was possible to return memories "knocked out" of the brain by chemical means. To do this, they subjected mice placed in a cage to electric shock, as a result of which they developed a protective reaction (fading). After a while, the rodents began to freeze when they got into the cage, even in the absence of an unpleasant stimulus. Then parts of the mice were injected with the drug anisomycin, which inhibits protein synthesis. Thus, he weakened synaptic connections and contributed to amnesia.
Other mice (control group) received a harmless saline solution. As expected, when mice with erased memory got into the cage, the protective reaction did not turn on.
Then, to find out whether the memory of the electric shock disappeared from the brain of experimental mice (or simply turned out to be blocked), scientists turned to optogenetics – the excitation of brain cells by light, which were given photosensitivity with the help of genetic engineering.
Neurophysiologists selectively activated the neurons responsible for the memory of an unpleasant experience – but by placing the mice in another cell. It turned out that mice with amnesia froze as often as rodents from the control group, despite the fact that they forgot about their stay in the room with electric shock.
Scientists explain this phenomenon by the fact that various processes are responsible for creating (encoding) and extracting memories. During the period of learning (memory creation), the connections between cells in different parts of the brain are strengthened so much that there is no need to strengthen synaptic connections to store them – unlike extraction. Thus, it is possible to regain the memory lost as a result of injury or illness.
"With retrograde amnesia, memory is not erased – access to it is simply lost. Our results are intended to stimulate new research on the biology of memory and its recovery in clinical settings," Tonegawa notes (in a press release MIT Researchers find "lost" memories – VM).
In 2013, the scientist became famous for introducing false memories to experimental mice. In 2014, a neurophysiologist successfully changed the emotional coloring of memories to the opposite, influencing the neurons of the brain with light.
Portal "Eternal youth" http://vechnayamolodost.ru02.06.2015