by Abbey Perreault '16
Remember the movie Inception? Well, ladies and gentlemen, the moment you’ve been waiting for has finally arrived: inception is real…except this time, the protagonists are a little less hunky. Last year at the Picower Institute for Learning and Memory at MIT, a group of researchers successfully used a technique called optogenetics to plant false thoughts in the minds of rats. (And, believe it or not, it was all accomplished without any dream-infiltrating espionage courtesy of Leonardo DiCaprio!)
How, you ask? The rats were first placed in one context (context A) and allowed to explore their environment. By monitoring neural activity, the researchers tracked and labeled the cells that were activated as the rats familiarized themselves with this context. Most of these activated neurons were located in the dentate gyrus of the hippocampus, the “memory center” of the brain.
The rats were then placed in a different context (context B). Here, the researchers administered a series of foot shocks to the rats. During this fear conditioning, researchers used optogenetic stimulation to “recreate” the experience of being in context A. In other words, they inserted an optic fiber into the dentate gyrus of the hippocampus. By shining light on the neurons that were tagged in context A, the researchers activated neural circuitry associated with context A. Essentially, the rats were optogenetically induced to re-experience context A while being shocked in context B. When placed back in context A, the rats exhibited fearful freezing behavior, as if they had actually been fear conditioned in this environment.
Think of it this way: you love nothing more than spending your Sunday afternoons reading the paper at your favorite coffee shop. Across the street, there’s a mad scientist who owns a teahouse that is never frequented (probably because he is a mad scientist and people fear that he serves non-FDA-approved chemical concoctions in his tea). He monitors your hippocampal activity while you enjoy your cozy coffee shop experience, and then, when you’re least expecting it, snatches you and brings you across the street. In his lab, he shows you pictures of terrifying clowns while stimulating the hippocampal neurons that code for “Sunday coffee shop.” Next Sunday, you enter the coffee shop only to find yourself racked with fear and pervasive, horrifying clown imagery. You infer that something terrible has happened to you here and decide to resituate yourself in the teashop across the street to read your morning paper. The mad scientist laughs maniacally as he serves you chemical-filled tea.
Unfortunately for him—and quite fortunately for you—the study has only been successfully completed using rodent subjects. If it were to be replicated using human subjects, the implications would be nearly inconceivable and, quite frankly, terrifying. What would it mean to have the ability to artificially create false associations that are functionally real? Could a replication of this technique using pleasurable rather than fearful stimuli offer a promising mechanism to deal with phobias or other forms of anxiety-related mental suffering? Or—let me get all George Orwell on you for a moment—could this ever be abused for something like thought-control tactics in our society?
Perhaps not. Perhaps this could never be successful with human subjects in the first place. But as the field of neuroscience continues to rapidly advance, optogenetic artificial thought manipulation certainly seems like a feasible possibility. Who knows—perhaps poor DiCaprio can employ these mechanisms of optogenetics off-screen to convince the Oscar Panel to finally let him win…
1. Liu X, Ramirez S, Pang PT, Puryear CB, Govindarajan A, Deisseroth K, et al. (2012). Optogenetic stimulation of a hippocampal engram activates fear memory recall. Nature [Internet]. 2012 April [cited 2014 March 12];484:1-5. Available from http://www.nature.com/nature/journal/v484/n7394/full/nature11028.html