Move over, breast implants, make way for a future where it’s possible to implant something a bit more profound: memories. But hey, you could always implant a memory in which you or your girlfriend is a double D.
Science fiction such as long explored the implications of toying with memories, whether by deleting them, amending them, or creating artificial ones. After all, that what movies like Total Recall, Inception, and Eternal Sunshine of the Spotless Mind, are all about. Building on last year’s work in which scientists from the University of Southern California tried to suppress and implant memories in rats, neuroscientists at MIT have published a study in which they were able to activate artificial memories, using something called an “engram,” in a mouse’s brain. An engram is the trace of a memory that is encoded, or stored, in cerebral neurons. When we remember something, these engrams become active. Failure to recall something specific indicates either some kind of corruption in the engram, or a disruption in the hippocampus, the brain’s control center, when trying to access the memory. Scientists have long believed that stimulation of neurons in an engram provide access to a specific memory.
Now, it doesn’t matter whether that specific memory is real or if it’s been artificially implanted. The researchers were able to make mice remember things that never actually happened. MIT neuroscientist Susumu Tonegawa led the project in which the first step was to genetically engineer mice that expressed a specific protein, ChR2, in hippocampus neurons that help form memories. This created a way for Tonegawa and his team to know exactly which brain cells to work with in order to encode engrams. The ChR2 protein is light-sensitive, which means that light causes the cells that house the protein to activate, allowing the researchers to promote the encoding of new memories.
After performing all these neat genetic tricks on the mice, researchers then put them into a safe chamber, allowing them to encode memories of that space as comfortable and harmless. Then, they put the mice in different chamber, and, employing a technique called optogenetics, used an optical fiber implanted in the brains of the mice to reactivate the engram established in the previous location. While the mice were busy remembering that first, safe space, researchers shocked their feet. Because of the already confirmed ability of mice to be conditioned to recall fear based on a previous painful experience, they wanted to see what would happen if they induced the memory of an experience, rather than the experience or even the setting itself.
The researchers put the rodents back into the first chamber, the safe one, but the mice froze in fear. Despite that the chamber was harmless, recalling that space while being shocked was enough to make the mice believe it wasn’t safe at all—that, in fact, it was the same place where they received the shock. When the mice were put back into the shock chamber, they also experienced fear, but the researchers claim that the fear expressed by the mice when they had their memory of the first space activated and were then put back into it was even greater.
So, what does all of these mean? First, that there are some pretty fucked up mice out there. I hope they get lots of cheese, maybe some foot rubs, and some intense therapy. Second, this may help us explain why memories do funky things, such as conflate. Maybe it’s just because I’m getting old, but I often remember an experience correctly, but misremember the environment or context. Or sometimes two memories merge in my mind for whatever strange reason. The MIT study begins to shed some light on how this happens.
Third, it’s clearly possible to manipulate neural connections and thus, memories. Optogenetics is only one way of altering memories (electrical stimulation and microchips are others). This means that, at least theoretically, people could be programmed to associate places with emotions, even if the places are new, or that a bad experience could, with a little tinkering, activate engrams of positive experiences. While the implications could certainly be useful for people with memory loss, it’s pretty easy to see how memory manipulation could lead to a dystopia where nothing—not even your own recollections—can be trusted. Maybe I’ll just choose to forget this is even possible, while I still can.