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Memories Can Be Deleted Without Affecting Others: McGill-Columbia Study

The study tested snails but said similar results were possible in humans.

07/07/2017 16:24 EDT | Updated 07/07/2017 16:33 EDT
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It might be possible to delete traumatic memories without influencing other ones, according to researchers from McGill and Columbia University.

The mind-blowing findings were published last month in Current Biology.

Researchers found that multiple memories can be encoded together during and after emotional or traumatic events. Important details linked to that are characterized as associative memories, but seemingly irrelevant ones — known as incidental memories — can trigger reactions like anxiety attacks.

With the help of medicine, scientists believe they can erase those incidental triggering details from one's memory, something of particular aid to people with anxiety or post-traumatic stress disorder.

"The example I like to give is, if you are walking in a high-crime area and you take a shortcut through a dark alley and get mugged, and then you happen to see a mailbox nearby, you might get really nervous when you want to mail something later on," said Samuel Schacher, a professor of neuroscience at Columbia and a study co-author, in a news release.

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If scientists can delete incidental memories in humans, they could remove the fear of mailboxes but leave the reasonable memory directly associated with the trauma — for example, fear of dark alleys.

Schacher explained the research focuses on strategies to delete "problematic non-associative memories" without hurting "associative memories, which can help people make informed decisions in the future — like not taking shortcuts through dark alleys in high-crime areas."

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Aplysia sea mollusks, similar to this one, were used in the study.

The researchers used Aplysia snails in their tests because their large nervous systems are easy to understand and manipulate, and their neurons are also big.

In experiments on sensory and motor neurons, scientists realized the connections for an associative (unwanted) memory, or a non-associative (necessary) memory in a snail's brain could be deleted by blocking different protein molecules.

Basically, the results suggest that it's possible to eliminate some memories without losing others on the same neuron.

Schacher Lab/Columbia University Medical Center
Two sensory neurons (smaller grey circles) of an Aplysia snail are connected to a motor neuron (which is red because it's been injected with a fluorescent molecule).

Researchers hope the findings will open the doors to new research in human memory because people have similar proteins that help form memories. CTV reported human trials could begin in as little as five years.

"By isolating the exact molecules that maintain non-associative memory, we may be able to develop drugs that can treat anxiety without affecting the patient's normal memory of past events," said co-author Jiangyuan Hu.

He acknowledged that the ethical implications of deleting memories still need to be considered.

This adds to the body of work from Canadians. Earlier this year, researchers at Toronto's Hospital for Sick Children said they were able to isolate and delete fearful memories in lab mice.

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