A man approaches the bedside of his elderly mother, now (perhaps) unconscious. He would like to tell her so many things, but above all he would like her to be able to share with him one last memory, one last precious image of her life. Until a few years ago, it would have been impossible: but the extraordinary progress of neuroscience are opening up scenarios that until yesterday were pure science fiction. The recovery of memories from the brain of a person in a coma, or even deceased is no longer just a novel idea, but a real scientific challenge, even if it is still to be won.
Because our memories are much more than simple “files” stored in a biological memory: they are experiences, emotions, relationships that define us as individuals. And perhaps, one day, they could be our most precious legacy.
Mind, the final frontier
Imagine being able to relive the most precious memories of a loved one who is no longer with us. Being able to hear from their voice the story of that unforgettable vacation, of that first kiss, of that immense joy at the birth of a child. It seems like a dream, yet science is beginning to explore the possibility of memory recovery directly from the brains of deceased people.
This is both exciting and disturbing, because while it would represent an incredible step forward in our understanding of the human mind, it also raises profound ethical and philosophical questions. But how exactly does our memory work? And what obstacles will researchers have to overcome to access the memories stored in a brain that has ceased to live?
Neurons, Synapses and Memory Traces
In our brain, every experience, every face, every emotion leaves a physical trace, a sort of "fingerprint" called engram. This is a set of neurons interconnected via synapse, which are activated together every time we recall that particular memory. A sort of “unique combination” for any fragment of our experience.
Scientists have been able to identify these clusters of neurons in certain areas of the brain, such as the hippocampus, seat of short- and long-term memory. Theoretically, if we had a complete “map” of the human brain, we could locate the engram corresponding to a specific memory we wanted to retrieve.
Recovery mission in a web of memories
The problem of the memory, as mentioned, is that our memories (especially the long-term ones) are not static “files” stored in a specific point, but complex experiences scattered across different brain areas. Sensory details in one part, associated emotions in another, the space-time context in yet another (as a well-known study has agreed published in Nature in 2012).
Every time we recall a memory, the engram neurons activate like a sort of “cascade”, reconstructing the original experience from these scattered fragments. Not only that: as time passes, memories migrate, transform, mix with others in an increasingly dense web. In short, our memory is more like a Spider web than to an orderly archive.
The Challenge of Recovering Post-Mortem Memories
Even if scientists could precisely map the location of engrams in a living person’s brain, recovering memories after death would present several technical challenges. It would not be enough to “extract” neurons, because the engram itself is not the memory, but only the “place” where it is stored.
It would take a even more complete model of the brain of that person, taking into account all the synaptic connections formed during his or her life. A task at the limits of current technological capabilities and perhaps impossible without a “chronology” of brain scans performed when he or she was still alive.
To remember is to imagine
Then there is a deeper obstacle, which has to do with the very nature of our memory. As the neuroscientist explains Charan Ranganath ofUniversity of California,
In reality, with our memories we do not review the past, but we imagine how it could have been.
Our memories, in essence, are not a faithful recording of events but a influenced reconstruction from our state of mind, from our beliefs, from hindsight. Every time we recall them we reshape them, adding meanings and nuances. In a certain sense, remembering is always a bit of reinventing.
The Last Secret of the Mind
In short, the complete recovery of memories from the brain of a deceased is an undertaking that, at present, seems destined only for science fiction. But research goes on, driven by the hope of revealing the last, the most intimate of the mysteries of the human mind.
Perhaps, one day far away, we will have a gadget to wear on important occasions, to record all the paths of our brain in those moments. And someone will really be able to relive our memories, bringing back to life for an instant our voice, our smile, our gaze. Or perhaps, more simply, we will learn to accept that certain things (the most precious, the most personal) are destined to fade away with us.
And that's what makes them unique.
