Barbara J. King
You may have heard about last week's announcement that scientists implanted false memories in laboratory mice. The paper, published by Nobel Laureate Susumu Tonegawa and co-authors in the journal Science, explains how mice were caused to "remember" a scary an environment that was actually neutral.
Here's the procedure in a nutshell: Hippocampus neurons of mice firing to make memories in a non-scary environment were labeled, then activated with light when the animals were put into a second, different environment. In this second location, during the neurons' forced activation — when the act of remembering the first environment was underway — the mice received mild foot shocks.
Later when the mouse was put back into the first environment, it showed behavioural signs of fear, indicating it had formed a false fear memory for the first environment, where it was never shocked in reality.
This is a significant development in neuroscience, though clearly aversive for the mice. But I want to wander a bit afield from the empirical work itself, and consider some of its potential implications for our own species.
Scientists have known for a long time that human memory is both unreliable and reconstructive, that is, we modify our memories heavily as we revisit them. But why would evolution have allowed the brain to be built in such a way? What's the benefit?
Speaking to the The New York Times, study scientist Tonegawa speculated that the benefit may have to do with the creativity that underlies human artistic and scientific endeavors, which depends on thinking freely about both real and imagined events. This thought makes sense to a biological anthropologist like me.
Of course, other animals may think, and may imagine. We know that wild and captive chimpanzees play games of imagination, for instance, and that traumatized elephants may dream, apparently re-living nightmarish events that are not happening in present time.
During human evolution, though, the ability for creativity of this sort soared to unprecedented levels. All cultures routinely spin yarns to each other, creating worlds of fiction through story telling by way of a dynamic social process that emerges from interactions with relatives, friends, rivals, allies and more. As someone who works intensively with evidence of thinking and feeling in non-human animals, I know this unprecedented ability of ours doesn't make us somehow superior creatures — nor of course does it make us more evolved. It does make us different.
But will this special brand of creativity, coupled with modern scientific advances, tumble us into uncharted ethical waters faster than anyone has realized? Steve Ramirez, a co-author on the Science paper, and Mark Mayford, a neuroscientist who works with memory, hinted as much in an interview last week for NPR's Science Friday.
Using techniques grounded in the rodent false-memory work, they suggest, we may soon be able to alter the emotional valence of human PTSD-like memories, or even significantly reconfigure the stuff of human mood disorders.
It's clear to me that memories, though, don't live on only in our brains. Just as our story telling and the making of new worlds emerge in a rich social dynamic, so does the process of altering our memories by revisiting them. It is as we talk, laugh, revisit the past, argue and tell jokes with others that our memories alter. And as they alter, might not the ongoing interactions and relationships sometimes alter too?
As my 13.7 co-blogger Alva NoŽ wrote here last month, it's not our brains that make meaning — it's we ourselves, fully embedded in our social networks:
How could brains make meaning? They can't ... . Our brains carry information and significance only thanks to the way they, and we, are embedded in complex causal networks.
We like to think that our thoughts are inside. We reveal them to others by making them external in the form of action, words, writings, messages and the like. That's all well and good for describing ordinary life. We can keep secrets. We can publicize our deepest yearnings.
But actually, there is no inside. Or rather, use any device you like — from the scalpel to the brain scan — and you won't find meaning, significance, value, in the head ... . The very inside/outside distinction breaks down.
And so, what would happen — or might happen — when a scientific team tweaks the emotional valence of a memory for another person? There's an irony here: As good as our brains are at imagining new worlds, are they good enough? Can we foresee the potentially cascading effects of making a stressful memory a bit less stressful, or of extinguishing a nasty memory altogether?
This is what my brain wonders today.