Genetic switch may erase unpleasant memories: study

Unpleasant memories can be erased by switching off a particular gene, a new study in mice has found.
Dementia, accidents, or traumatic events can make us lose the memories formed before the injury or the onset of the disease, researchers said.
Scientists from KU Leuven in Belgium and Leibniz Institute for Neurobiology in Germany have now shown that some memories can also be erased when one particular gene is switched off.
Researchers trained mice that had been genetically modified in one single gene: neuroplastin. This gene, which is investigated by only a few groups in the world, is very important for brain plasticity.

In humans, changes in the regulation of the neuroplastin gene have recently been linked to decreased intellectual abilities and schizophrenia, researchers said.
For the study, mice were trained to move from one side of a box to the other as soon as a lamp lights up, thus avoiding a foot stimulus. This learning process is called associative learning, they said.

Its most famous example is Pavlov's dog: conditioned to associate the sound of a bell with getting food, the dog starts salivating whenever it hears a bell, researchers said.
When scientists switched off the neuroplastin gene after conditioning, the mice were no longer able to perform the task properly.

They showed learning and memory deficits that were specifically related to associative learning. The control mice with the neuroplastin gene switched on, by contrast, could still do the task perfectly, researchers said.
"We were amazed to find that deactivating one single gene is enough to erase associative memories formed before or during the learning trials," said Detlef Balschun from KU Leuven.
"Switching off the neuroplastin gene has an impact on the behaviour of the mice, because it interferes with the communication between their brain cells," said Balschun.
By measuring the electrical signals in the brain, researchers discovered clear deficits in the cellular mechanism used to store memories.

They found that these changes are even visible at the level of individual brain cells.
The findings were published in the journal Biological Psychiatry.