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Remember when Will Smith and Tommy Lee Jones used the neuralyzer to erase people’s memories with blue light in Men in Black? Well, we can’t do that yet, but some scientists have done something remarkably similar. On October 9th, UC Davis announced that researchers there have “erased specific memories” within mice using light.
The secret to the technology lies in a fascinating field called optogenetics, and it’s already started to change how we think about the brain.
What Is Optogenetics?
Optogenetics is a very recent field by scientific standards, having only been around since 2002. If you’re familiar with scientific naming conventions, you’ve probably realized that optogenetics combines light (opto) and genetics — but how this works is surprising (and really cool). First, a quick lesson in neuroanatomy.
The brain is made up of trillions of neurons, each of which is connected to many other neurons, the same structure reflected in artificial neural networks and neuromorphic chips. When a neuron is activated, or “fires,” it communicates with other neurons and creates a cascade of neural activity — this is what causes thought and action (for more details on how the brain works, check out the HowStuffWorks explanation).
So what does light have to do with that? Usually, nothing. However, with a bit of genetic modification, scientists have been able to breed mice whose brains contain neurons that are responsive to light, meaning that when a certain set of neurons are exposed to a very specific wavelength of blue light, they can be turned on or off.
This has been used in small animals, like nematodes and roundworms, to induce muscle action, and it’s even been used to get a mouse to run with the flick of a switch (the link goes to a video of the experiment; it’s pretty cool, but I decided not to embed in case you’d rather not see animal testing in action—that said, it’s not too bad).
When it comes to the brain, however, things like motor activation and neural circuit mapping aren’t as complex as modifying memories. Scientists have been studying memories and cognition for a long time, and there’s still disagreement over how it works and what the relationship is between a neuron or a group of neurons and particular cognitive functions.
“A Standard-Issue Neuralyzer”
The recent UC Davis research accomplished a major breakthrough in optogenetics and memory. To really understand what was going on in that research, I’ll walk you through the experiment.
Long before the experiment, mice were genetically modified so that their neurons could be affected by blue light. A tiny light was implanted in the brain of the mouse to provide the necessary optical stimulation, and then the experiment began. In this particular experiment, the mice were placed in a cage that gave them a small electric shock. Once they had learned the association between the cage and the shock, they would freeze immediately upon being put into that cage; this is called a fear response.
After the mice had learned this response, the researchers triggered the blue light, which was aimed at specific neuronal clusters. The mice, when reintroduced to the shock cage, no longer showed the fear response—they had “forgotten” what they were afraid of.
Of course, saying that the researchers had erased the memories of the mice is a bit of an oversimplification; this was a very simple conditioned memory and response, and it was suppressed by the application of the blue light.
With that said, it’s definitely a step forward in how we understand the brain (if you’re interested in the neuroanatomy of the experiment, it showed that the hippocampus and the cortex are both involved in memory retrieval, and that the cortex can’t do it alone. It also showed that specific parts of the hippocampus are activated during memory retrieval).
While you don’t have to start worrying about someone zapping your brain with blue light and erasing your memories any time soon, this does provoke some very serious questions about the future of optogenetic research. No research has been conducted with humans yet, but recent studies have used primates, so it seems likely that humans are on the schedule. Because of the genetic component, it could be quite a while before this happens (if you want to see it for yourself, you might want to consider putting your brain on ice and checking back in after few decades).
It’s not hard to imagine that someone out there is trying to figure out how to find a wavelength of light that would work without the genetic component. Whether or not this is possible is certainly outside the scope of this article, but it does make for an interesting thought experiment. If scientists figure out how to manipulate neurons without previous genetic manipulation, we could someday see a world straight out of Dollhouse (and if you haven’t seen Dollhouse, I recommend it).
What do you think of this research? Think we could be headed toward pocket-sized neuralyzers? Share your thoughts below!
Image credit: LED background with dozens transparent blue LEDs.