Scientists Hacked Monkey Brains to Electronically Control Their Decisions

The new study adds to a growing body of work that suggests brains can be manipulated with a surprising degree of precision.

A rhesus macaque. Image: Peter Nijenhuis/Flickr

While your brain should still be safe from hackers for some time yet, a new study, in which macaques had their choices controlled by electrical impulses, adds to a growing body of work that suggests brains can be manipulated with a surprising degree of precision.

Using electrodes implanted in the ventral tegmental area (VTA), a region deep in the brain associated with the reward circuitry of the brain, researchers were able to fundamentally influence the decision making of macaques. The work was published today in Current Biology.

The study, conducted by a joint team from KU Leuven in Belgium, Massachusetts General Hospital, and Harvard Medical School, consisted first of an A/B test in which macaques were shown a pair of images, and their preference for one or the other recorded. Some monkeys might prefer a picture of a ball, others a star, but in any case, the research team was able to glean a baseline preference for each individual.

Then came the big test: Could electrical microstimulation affect the results? Indeed, by applying small, regular electrical impulses to the VTA, the team "was capable of selectively reinforcing and motivating behavior during operant and Pavlovian conditioning paradigms." In other words, after flipping the switch, macaques that preferred image A picked image B, and vice versa.

I asked Wim Vanduffel, a co-author of the report, if the results suggest that electronically-controlled decision making is possible, to which he emailed, "Certainly so!"

The team used fMRI imaging to guide implantation of the electrodes.

"The data show that the preference of the monkeys changes quite dramatically," he wrote. "The effect was slightly larger in the first compared to the third animal, likely because of the positioning of the electrodes (but that is speculation)."

Of course, it's more complex than simply plugging a wire into a monkey's brain and controlling what it does. For one, the team, led by John Arsenault, still had to convince the macaques to actually go along with the game, which meant adding in an additional juice reward; the animals didn't suddenly turn into robots.

"Indeed, we could not have the monkey 'work' for microstimulation alone," Vanduffel wrote. "In other words, to reinforce the operant behavior we used an additional reinforcer (juice)."

And lest you fear that your brain could be taken over by someone on the street, the effect of electrical stimulation on decision making requires the extremely precise placement of electrodes deep into the brain—something not likely to happen without you knowing.

"The targeting itself is probably 'ever lasting': once the electrodes are in the right locations (and if there are no complications), they probably will work for long periods of time," Vanduffel wrote. "The critical issue is to reach a sufficiently large number of VTA neurons. So positioning is very important—and not trivial."

Postoperative image confirming the planting of electroding in the VTA, deep in the brain.

I particularly like the way Vanduffel put it in a release, saying, "Of course, there is also a potential danger here: The method could be used maliciously to manipulate a person's brain remotely without his knowledge. But as yet, there is no reason to worry. Non-invasive, high-precision methods for stimulating deep brain centers are not yet available."

Regardless, it's more evidence that stimulating the brain is indeed possible. Previous work has focused on optical stimulation, including particularly futuristic research into controlling mice brains with lasers. Deep brain stimulation is already used in humans, but not with the direct decision-making effects of the most recent study. 

Perhaps the closest to the brain hacking concept—albeit for good—is DARPA's interest in developing brain stimulation therapies for treating brain trauma, including PTSD. So while we're a ways off from worrying about people hijacking our brains or an offshoot from the Matrix scenario, it's becoming increasingly apparent that the brain's electrical processes can be manipulated with a fine degree of precision—and, one day, we may even be able to copy them.

"We've known for a long time that the 'working of the brain' can be reduced to the electrical activity of neurons," Vanduffel said. "If one were able to 'mimick' this artificially, one would have a working brain. Obviously, this is purely hypothetical since it seems impossible to mimick ~100 billion neurons, and many more connections between them."

Regardless, that we can tap into the electrical systems of the brain means a future where we can regulate our brains with more control than we can imagine now. It's an area with huge potential for treatment of neurological disorders, as electrical implants could perhaps act with more precision than pharmacological treatmeants—just as long as they don't get hacked.