What if you could control somebody's desires using a wireless device? It's not a Larry Niven novel — it's today's science. Researchers used a remote controller to stimulate neurons in mice that release the reward chemical dopamine. As a result, they changed the behavior of the mice, from a distance, in the absence of any tangible reward.
And they did it using optogenetics, an emerging field of research in which living, cortical neurons and other cells can be manipulated or controlled with optical technology (typically with fiber optic cables). It’s only been tested in nonhuman animals like rodents and monkeys, but it could eventually be used to treat such things as heart conditions, paralysis, and even diabetes.
But now, as new research from Washington University School of Medicine in St. Louis and the University of Illinois at Urbana-Champaign has shown, optogenetics could also be used to stimulate the brain's reward and pleasure pathways — all without unwieldy wires or cables stuck into the brain.
In the new study, which has now been published in Science, a research team co-led by Washington University’s Michael R. Bruchas demonstrates how optogenetic effects can be triggered over wireless.
To make it happen, the researchers developed multicolored microscale, inorganic light-emitting diodes (µILEDs) that are just 6.45 microns thick (that's thinner than a human hair and about the size of an individual neuron). The µILEDs were implanted into the brains of mice who were genetically engineered to have parts of their brain responsive to light. It was the first time these devices were used in an optogenetics experiment for the purpose of testing on freely moving animals.
Once the implants were inserted deep inside a mouse’s brain (nailing the exact location, or pathway, was critical), it was placed in a specially designed maze outfitted with a series of holes. But each time it poked its nose through one hole in particular, the cellular-sized µILEDs stimulated dopamine-producing cells in its brain (all the other holes did nothing). As a result, the mouse was rewarded for its behavior in the same way that we would be “rewarded” after biting into, say, a piece of chocolate.
Dopamine makes us feel good, which can in turn reinforce (or condition) a particular behavior. In this case, the mice experienced pleasure each time they poked their noses through one specific hole — and all without receiving any real kind of reward (like food or visual stimulation).
As a result, the researchers "taught" the mice to poke their heads through the one hole, while disregarding the others.
Interestingly, the scientists also observed that the mice developed an associated preference for the area near the hole and they preferred to hang around that part of the maze.
Though this experiment might seem a bit bizarre, the researchers are hoping to see these technologies applied to humans for pain management and the treatment of brain disorders like depression, anxiety, addiction, and sleep disorders. These implants could also be used to trigger specific responses in other organ systems.
“We believe these devices will allow us to study complex stress and social interaction behaviors,” Bruchas explained through a statement. “This technology enables us to map neural circuits with respect to things like stress and pain much more effectively.”
Read the entire paper at Science: “Injectable, Cellular-Scale Optoelectronics with Applications for Wireless Optogenetics.”
Supplementary source: Washington University in St. Louis.
Top image: MIT McGovern Institute & MIT Synthetic Neurobiology Group; interior images: Washington University.