Author: By Steve Connor, Science Editor
Researchers carried out their work on laboratory mice and they emphasise that it may be many years before it can be applied to humans, but the findings provide evidence that it is possible in principle to eliminate bad memories from a person’s mind.
The scientists concentrated on eliminating a memory of physical pain ? a mild electric shock given to the paws of the animals ? by interfering with the levels of a natural nerve chemical in the brain which seems to be involved in memory retrieval.
Tests on the mice showed that it was possible to make them forget about the painful incident. The scientists were also able to make the mice forget about having had a new toy to play with ? when the toy was returned to them they behaved as if they had never seen it before.
Interfering with memories could have a variety of uses outside the medical arena. In addition to eliminating the traumatic memories of war, the development could also be used on people who want to reinvent themselves by eradicating past experiences from their minds. This is similar to the plotline of the 2004 film Eternal Sunshine of the Spotless Mind, where the characters played by Jim Carrey and Kate Winslet have the memories of their troubled love affair eradicated by a New York firm specialising in creating selective amnesia.
Joe Tsien, of the Medical College of Georgia’s School of Medicine in Augusta, said the findings are important in understanding the basis for how memories are stored and retrieved in mammals ? including humans.
“While memories are great teachers and obviously crucial for survival and adaptation, selectively removing incapacitating memories, such as traumatic war memories or an unwanted fear, could help many people live better lives,” Dr Tsien said. “Our work reveals a molecular mechanism of how that can be done quickly and without doing damage to brain cells.
“But no one should expect to have a pill to do the same in humans anytime soon. We are barely at the foot of a very tall mountain,” he added.
The study, published in the journal Neuron, used genetically modified mice that had been specifically bred to overproduce a neurotransmitter called CaMKII (alpha calcium-calmodulin-dependent protein kinase two), which is involved in memory.
The scientists found that high levels of CaMKII appeared to trigger the rapid erasure of stored memories and that only those memories that were in the process of being retrieved were actually erased, while other ones remained intact.
Dr Tsien said that memories are formed in the brain by the strengthening of the chemical connections between different nerve cells, yet by interfering with the way CaMKII works in the brain it is in effective possible to lose a memory.
Like a war veteran remembering a fateful patrol when he was fired upon, a mouse can recall the experience of a painful shock, if they return to the place where they had felt the pain, Dr Tsien said. The researchers showed that if the mice overproduced CaMKII in their brains, this powerful memory of a painful experience was rapidly erased as the animals tried to retrieve them, while their other memories remained intact. One possible therapy for humans could be a drug designed to mimic the overproduction of CaMKII in the brain. However, such a treatment for bad memories in humans is still many years away.
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