The concept of implanting a person with false memories has been featured in many a science fiction franchise. Between Philip K. Dick’s “We Can Remember it for you Wholesale” (which was the basis for Total Recall), the cult-hit Dark City, and the more recent Inception, the idea that memories could be tampered with – thus showing how reality and experience are subjective – has a long history.
And now it seems that once again, science fiction has proven to be the basis of science fact. As a result ongoing collaboration between the Japanese Riken Brain Science Institute and MIT’s Picower Institute for Learning and Memory, a process has been devised for planting specific false memories into the brains of mice.
This breakthrough, in addition to being mind-blowing and kind of scary, is also likely to seriously extend our understanding of memory. The ability to learn and remember is a vital part of any animal’s ability to survive, but with human beings, it also plays a major role in our perception of what it is to be human. What’s more, disorders effecting the human brain and memory have been growing considerably in recent decades.
These range from Alzheimer’s disease, where the abilities to make new memories and to place one’s self in time are seriously disrupted, to Post-Traumatic Stress Disorder, in which a memory of a particularly unpleasant experience cannot be suppressed. Such disorders are a powerful force driving research into discovering how healthy memory functions so that we can diagnose and treat problems before they become too serious.
In their previous work, researchers from the Picower Center for Neural Circuit Genetics were able to identify an assembly of neurons in the brain’s hippocampus that held a memory engram – a cell containing data about a sequence of events. In recalling a memory, the brain uses this data to reconstruct the associated events, but this reconstruction often varies from what actually occurred.
Working from this, the researchers were able to locate and identify the neurons encoding a particular engram (a specific set of memories) through the use of optogenetics. This technique is a relatively new neuromodulation process that uses a combination of genetic modification and optical stimulation to control the activity of individual neurons.Afterward, they were able to genetically engineer the hippocampal cells of a new strain of mouse so that the cells would form a light-sensitive protein called a channelrhodopsin (ChR). These proteins activate neurons when stimulated by light, thus ensuring that specific memories could be triggered by exposing someone implanted with them to a light source.
Next, the researchers conducted a series of behavioral experiments in order to identify the set of brain cells that were active only when a mouse was learning about a new environment. The genes activated in those cells were then coupled with the light-sensitive ChR and monitored during the next phase of the experiment, where the mice were placed in a series of boxes.
In the first box, the mice were exposed to a safe environment, during which time the neurons that were actively forming memories were labelled with ChR, so they could later be triggered by light pulses. In the second box, mice were treated to a series of mild foot shocks, which created a negative association, while at the same time, a pulsing light was used to trigger their memories of being in the first box.
When the mice were returned to the first box, in which they had only pleasant experiences, they clearly displayed fear/anxiety behaviors. In short, the fear that they had learned in a separate environment was now falsely associated with the safe environment. Whats more, the false fear memory could be reactivated at will in any environment by triggering the neurons associated with that false memory.
What this demonstrated was that the recall of this false memory drove an active fear response that was indistinguishable from a real memory. And according to Steve Ramirez, a graduate student in the Tonegawa lab and the lead author of the paper, the experiment provided some real insight into the nature of memory:
These kinds of experiments show us just how reconstructive the process of memory actually is. Memory is not a carbon copy, but rather a reconstruction of the world we’ve experienced. Our hope is that, by proposing a neural explanation for how false memories may be generated, down the line we can use this kind of knowledge to inform, say, a courtroom about just how unreliable things like eyewitness testimony can actually be.
Granted, it might not sound like Total Recall or Inception, but the basic premise is the same. And note how in those movies, no explanation was given as to how these false memories were fashioned – nor could they be, since no means yet existed. But now, using this technique, memories could be fashioned in one person, and then implanted in another.
Frightened yet? Well, you should be! If memory is one of the very things that define us as human beings, and we can’t be sure if the memories we have are real, our own, or someone else’s, then how can we be sure of anything? How do we even know who we are? Man, I’d be writing this into a story outline right now if it hadn’t already been done to death!
Until next time, guard your experiences and memories jealously! You never know when someone might try to come along and steal them…