Researchers at the University of California, Riverside have developed a technique to selectively erase fear memories by weakening connections between the nerve cells involved in forming such memories.
Memories can be triggered by stimuli such as sights, sounds, and smells. Some memories are formed during traumatic events, and in this case stimuli associated with the trauma can trigger a fear response if a person encounters them later. For example, an army veteran may feel uncontrollable fear if they see a helicopter. These fear memories can cause difficulty for people with post-traumatic stress disorder (PTSD).
The research team set out to see if they could selectively weaken such memories in mice. The investigators first created a fear memory in the mice by giving them a small electric shock while playing a high-pitched tone. After a while, the mice associated the tone with the shock, and showed signs of fear when the tone sounded, even if they did not receive a shock.
The team then used a technique called optogenetics, using which genetically-modified nerve cells can be switched on or off using pulses of light, to selectively switch off the nerve cells involved in the fear memory, causing a reduction in the fear response. “We were able to stimulate just those neurons that responded to the high-pitch sound. Using low-frequency stimulations with light, we could erase the fear memory by artificially weakening the connections conveying the signals of the sensory cue (the high-pitched tone),” said Jun-Hyeong Cho, a researcher involved in the study.
“This study expands our understanding of how adaptive fear memory for a relevant stimulus is encoded in the brain,” said Cho. “It is also applicable to developing a novel intervention to selectively suppress pathological fear in PTSD.”
Here’s UC Riverside video about how the technology works: