Deep-seated fears, like the memory of a death or war-time trauma, can be crippling. They’re also notoriously hard to study and treat, says neuroscientist Ossama Khalaf, Ph.D. But finally, we’re making progress. In a Science paper published Thursday, Khalaf and his team show new evidence suggesting fearful memories that dwell deep in the brain’s neural circuitry don’t have to be a burden forever. It’s possible, the paper suggests, that they can be rewired.
The paper is rooted in the science of engrams — the idea that memories leave a physical trace in the brain. In this case, Khalaf, a researcher at École Polytechnique Fédérale de Lausanne, and his team traced deep-seated memories of fear of fear of fear of fear in rats back to the activity of specific neurons. They found that the way those neurons fire — and thus the fearful memory they encode — can be reprogrammed.
“In our study, we are providing the first experimental evidence that fear memory attenuation is mediated by the re-engagement of the original fear rewriting it towards safety,” Khalaf tells Inverse via email.
First, Khalaf and his team wanted to know what types of neurons fire when a deep-seated trauma — maybe a memory of a near-death experience — is remembered. They did this by traumatizing rats by repeatedly putting them in a box where they received mild electric shocks to their feet. Unsurprisingly, the rats eventually learned to fear the box — the experimental equivalent to a human having a deep-seated fear memory. Looking at the rat brains showed that these fears were associated with a specific pattern of neuron firing.
Then, they tried to rewrite those memories.