Researchers at the Weizmann Institute of Science have finally managed to erase one type of memory in mice. Reportedly, they have shut down a neuronal mechanism in the brain by which memories of fear are created. After the experiment, the mice showed a "fearless" behavior, forgetting the things that previously shook them.
Per Science Daily, the new study may someday eliminate the traumatic experiences of humans. For one, people with post-traumatic stress disorder (PTSD) may soon say goodbye to stressful thoughts. Dr. Ofer Yizhar, the study's team leader, told the press that people tend to remember things they care about, may it be good or bad. This is also the exact reason why major ups and downs in one's life last longer, affecting PTSD patients.
In particular, the scientists examined two brain regions: the amygdala and the prefrontal cortex. The former is responsible for controlling emotions, whereas the latter controls cognitive functions like storing memories. Dr. Oded Klavir, Dr. Mathias Prigge, Prof. Rony Paz, and a graduate student named Ayelet Sarel make up the team of Yizhar.
In the process, the experts first used a genetically-engineered virus to mark the amygdala neurons that communicate with the prefrontal cortex. After that, they used another virus and injected a gene that encodes light-sensitive proteins into the said neurons. When illumination takes place, only the neurons containing the light-sensitive proteins are activated.
Now, once the researchers achieved the precise control over the cellular interactions in the brain, they started exploring behavioral patterns. Well, per Neuro Science news, the study showed that "less fearful" mice are more likely to venture farther than the others. They found that when the mice were exposed to fear-inducing stimuli, a powerful line of communication was activated between the amygdala and the cortex.
With that in mind, the mice whose brains displayed such communication signs were more likely to retain a memory of the fear. Eventually, they will act frightened every time they experience the same scenario. The scientists then developed an innovative "optogenetic" technique for weakening the connection between the amygdala and the cortex (through light pulses). Once the connection was weakened, the mice no longer displayed the same fear.
