Memories of Fear Could Be Permanently Erased, Study Shows (theguardian.com) 38
A new study unpicks why certain sounds can stir alarming memories, and reveals a new approach to wiping such memories from the brain. The Guardian reports: Published in the journal Neuron by Cho and his colleague Woong Bin Kim, the research reveals how the team used genetically modified mice to examine the pathways between the area of the brain involved in processing a particular sound and the area involved in emotional memories, known as the amygdala. In the first part of the experiment the team played both a high pitched and low-pitched tone to mice. But, when the high-pitched sound was played, the researchers also gave the mice a small electric shock to their feet. When the high-pitched tone was subsequently played on its own, the mice froze in fear; no such response was seen when the alternative, low-pitched, tone was played. The team then looked to see if there were differences between the high-pitch and low-pitch tone pathways in the brains of the mice, revealing that, among the mice exposed electric shocks, the connections within the "high-pitched" pathway had become stronger, while the other pathway remained unchanged. The team found that when mice were subsequently repeatedly exposed to high-pitched sounds without the shocks they lost their fear -- a process known as fear extinction.
But the team discovered that 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.
But the team discovered that 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.
