Generation of a Synthetic Memory Trace
Blade Runner and the Phillip K. Dick novel that it’s based on have as one of their central themes the philosophically intriguing idea of “implanted” memories. That is, androids “born” days ago could have years and years of memories implanted in them about their lives – lives which are completely artificial, designed by android engineers to make them feel and seem more human.
While implanting realistic life-history memories in humanoid robots is still science fiction (unfortunately?), implanting simple artificial memory traces in lab mice is, now, not. (OK, so I overdid it with the whole “Scientists Are Making Blade Runner Real” thing, but now that I have your attention, here’s some cool research.)
Mark Mayford and his colleagues at Scripps Univeristy in California, successfully created a “hybrid memory” – part natural, part artificial – in awake-behaving mice. Their research, published in the journal Science, is pretty amazing.
We investigated the effect of activating a competing, artificially generated, neural representation on encoding of contextual fear memory in mice. We used a c-fos–based transgenic approach to introduce the hM3Dq DREADD receptor (designer receptor exclusively activated by designer drug) into neurons naturally activated by sensory experience. Neural activity could then be specifically and inducibly increased in the hM3Dq-expressing neurons by an exogenous ligand. When an ensemble of neurons for one context (ctxA) was artificially activated during conditioning in a distinct second context (ctxB), mice formed a hybrid memory representation. Reactivation of the artificially stimulated network within the conditioning context was required for retrieval of the memory, and the memory was specific for the spatial pattern of neurons artificially activated during learning. Similar stimulation impaired recall when not part of the initial conditioning.
Mayford’s team created a strain of genetically engineered mice that had receptors in certain areas of their hippocampus (the brain region mostly responsible for the creation and storage of memories). The researchers could “mark” a memory using molecules that bind to the receptors, which eventually allowed them to reactivate a targeted memory. The marked memory for their mice subjects was of a harmless white room. The unmarked memory was of a black and white room, where the mice were electrically shocked.
When the mice were put in the hazardous second room, the marked memory was reactivated at the same time, creating a semi-artificial “hybrid” memory. The mice associated the shocks with this hybrid memory, and only showed fear reactions in the black and white room when the old memory was activated with the normal one. That is, some kind of imaginary hybrid room came to exist in their brains, and it was the artificial memory of such a room that they associated with shocks, rather than the sight of the black and white room alone, which elicited fear reactions in normal mice.
So, what’s the point of this experiment?
Well, first of all, the genetic technology they developed can further our general understanding of memory. Any tool that can (literally) highlight the active formation of a memory can help researchers learn how memories form, how they are maintained, how they are reinforced or forgotten, and even what happens to them in pathologies like Alzheimer’s. Secondly, the ability to alter, and in this case, create, memories has huge experimental potential, just as being able to alter an animal’s neurobiology with drugs and surgeries has immense experimental utility – it always helps to be able to precisely change variables.
Oh yeah, and we have to prepare ourselves for the android-filled future so we have the tools to control and create all kinds of goofy characters with made-up life histories. Right.
By Sam McDougel