Would recovering the memories of a deceased person really be a good thing? This is clearly not certain – art has addressed this question more than once. From a scientific point of view, it seems very difficult to hope to extract the entire memory from an individual’s brain. But a partial operation would however be possible in the long term.
In any case, this is what Don Arnold, neuroscientist and professor at the University of Southern California, said, interviewed by the online media Live Science. The academic explains how things could work out. First, it would be a question of identifying all of the neurons which coded a specific memory in the brain, then understanding how they are connected. Then, these cells would have to be activated in order to create an approximate neural network; this artificial reconstruction would make it possible to launch a machine learning process by imitating the functioning of the brain.
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An engram affair
Even if it is technically difficult, such a maneuver is possible, believes Don Arnold. Short- and long-term memories, which form in the hippocampus, are coded by groups of neurons. At the same time, other parts of the brain store different aspects of a memory, such as emotions and other sensory details. Groups of neurons associated with a single memory leave a biological trace in the brain, known as an engram. This can be absolutely essential in the process of retrieving specific memories.
In 2012, in a study published in the journal Nature, American researchers revealed that they had discovered in the engram of a mouse specific brain cells linked to the memory of an experience that provoked a feeling of fear in the animal. If science had a complete model of the human brain, which it doesn’t yet have, it could theoretically identify the location of the memory it wants to revive, says Don Arnold.
Yes, but here’s the thing: human memories can be complex, especially long-term memories that may be tied to places, relationships, or skills. Recovering memories of the deceased is even more complex, because distinct parts of a memory are scattered throughout the brain. For example, sensory details can be stored in both the parietal lobe and the sensory cortex.
According to another study published in March 2023 by the National Library of Medicine, neurons in a given engram are connected by synapses, the spaces between neurons where electrochemical signals flow. When a memory is triggered, it causes a chain of firing synapses between these groups, which may be stored in different parts of the brain. Initially, the neurons that were active during the original event constitute an engram. But over time, memories move to different places as they consolidate in the brain. “You get this sort of cascade of neurons that code for these different things and each one of them is connected in this engram.”specifies Don Arnold.
Could we consider cutting out the cells that form the engram? Not really, explains the neuroscientist: the engram is not really the memory itself, but just the place where the memory is stored. Thus, assuming that the engram is localized – either by modeling, or by an experiment on a person still alive, which to date is unlikely – it would be difficult to recreate the original event as it happened. was experienced by the deceased person. In short, for the moment, you can die in peace: no one seems able to posthumously reconstruct what is in your head.
