Scientists Assert They Will Soon be Able to Edit Human Memories

A new study of snail neurons suggests memories that trigger anxiety, PTSD could be ‘erased’ without affecting normal memory of past events.

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Scientists Assert They Will Soon be Able to Edit Human Memories
Two Aplysia sensory neurons with synaptic contacts on the same motor neuron in culture after isolation from the nervous system of Aplysia. The motor neuron has been injected with a fluorescent molecule that blocks the activity of a specific Protein Kinase M molecule. Credit: Schacher Lab/Columbia University Medical Center

Scientists recently discovered that two different memory use completely different processes in the same nerves. And the most fascinating is that the finding could challenge earlier research that had suggested human memories of traumatic events used the same nerves in the same ways, making them impossible to physically distinguish.

Scientists at the Columbia University Medical Center (CUMC) along with McGill University analyzed neurons from a marine snail called an Aplysia in order to test a hypothesis. This could explain why memories of incidents surrounding a bad experience can themselves trigger anxiety.

An experience that could harm an organism becomes encoded as an associative memory as the connections between neurons strengthen. They also are not always quite so cut and dried. For example, an organism might touch a hot surface as it hears a bell, or hear a dog bark nearby as they are assaulted. Sometimes the bell sound might be related but neurons still record the information in case it’s necessary.

And thus, some incidental human memories doesn’t do the individual any favors. They trigger anxieties that do little to help prevent them from future harm. They can interfere with a person’s life as encounters with similar innocuous mail-boxes produces a stress response, while offering no advantage in avoiding muggings in the future.

Researcher Samuel Schacher from CUMC said, “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.”

The synaptic tagging hypothesis asserts a weak stimulus that also can create a long-term memory if it’s paired with a stronger stimulation entering the nerve through a different synapse.

It will just require some changes to store the memory sparked by chemicals called plasticity-related proteins. They are tagged in some way at each synapse.

If these tags get separated, they would provide a physical property that could be exploited.

Schacher said, “One focus of our current research is to develop strategies to eliminate problematic non-associative human memories that may become stamped on the brain during a traumatic experience without harming associative memories, which can help people make informed decisions in the future like not taking shortcuts through dark alleys in high-crime areas.”

For consideration, scientists took a pair of snail sensory neurons connected to a single motor neuron. They stimulated one sensory neuron in a way that represented a strong associative memory. Additionally, the other neuron was stimulated to induce an incidental, non-associative memory.

By doing this, researchers found that the strength of the connections at each synapse was the result of two different types of protein called a kinase. They observed that blocking just one of these kinases prevented that particular experience from etching itself onto the neuron. Meanwhile, it could virtually erase the specific memory.

Mammals also have similar versions for these kinases. Means, our brains work in rather similar ways.

Jiangyuan Hu from CUMC said, “Memory erasure has the potential to alleviate PTSD and anxiety disorders by removing the non-associative memory that causes the maladaptive physiological response.”