Brain-to-brain interface allows transmission of tactile and motor information between rats

Researchers have electronically linked the brains of pairs of rats for the first time, enabling them to communicate directly to solve simple behavioral puzzles. Credit: Duke University Medical Center

Researchers have electronically linked the brains of pairs of rats for the first time, enabling them to communicate directly to solve simple behavioral puzzles. A further test of this work successfully linked the brains of two animals thousands of miles apart—one in Durham, N.C., and one in Natal, Brazil.

The results of these projects suggest the future potential for linking multiple brains to form what the research team is calling an "organic computer," which could allow sharing of motor and sensory information among . The study was published Feb. 28, 2013, in the journal Scientific Reports.

"Our previous studies with brain-machine interfaces had convinced us that the rat brain was much more plastic than we had previously thought," said Miguel Nicolelis, M.D., PhD, lead author of the publication and professor of at Duke University School of Medicine. "In those experiments, the rat brain was able to adapt easily to accept input from devices outside the body and even learn how to process invisible infrared light generated by an artificial sensor. So, the question we asked was, 'if the brain could assimilate signals from artificial sensors, could it also assimilate information input from sensors from a different body?'"

To test this hypothesis, the researchers first trained pairs of rats to solve a simple problem: to press the correct lever when an indicator light above the lever switched on, which rewarded the rats with a sip of water. They next connected the two animals' brains via arrays of inserted into the area of the that processes motor information.

One of the two rodents was designated as the "encoder" animal. This animal received a visual cue that showed it which lever to press in exchange for a water reward. Once this "encoder" rat pressed the right lever, a sample of its that coded its was translated into a pattern of that was delivered directly into the brain of the second rat, known as the "decoder" animal.

The decoder rat had the same types of levers in its chamber, but it did not receive any visual cue indicating which lever it should press to obtain a reward. Therefore, to press the correct lever and receive the reward it craved, the decoder rat would have to rely on the cue transmitted from the encoder via the brain-to-brain interface.

This video is not supported by your browser at this time.

The researchers then conducted trials to determine how well the decoder animal could decipher the brain input from the encoder rat to choose the correct lever. The decoder rat ultimately achieved a maximum success rate of about 70 percent, only slightly below the possible maximum success rate of 78 percent that the researchers had theorized was achievable based on success rates of sending signals directly to the decoder rat's brain.

Importantly, the communication provided by this brain-to-brain interface was two-way. For instance, the encoder rat did not receive a full reward if the decoder rat made a wrong choice. The result of this peculiar contingency, said Nicolelis, led to the establishment of a "behavioral collaboration" between the pair of rats.

"We saw that when the decoder rat committed an error, the encoder basically changed both its brain function and behavior to make it easier for its partner to get it right," Nicolelis said. "The encoder improved the signal-to-noise ratio of its brain activity that represented the decision, so the signal became cleaner and easier to detect. And it made a quicker, cleaner decision to choose the correct lever to press. Invariably, when the encoder made those adaptations, the decoder got the right decision more often, so they both got a better reward."

In a second set of experiments, the researchers trained pairs of rats to distinguish between a narrow or wide opening using their whiskers. If the opening was narrow, they were taught to nose-poke a water port on the left side of the chamber to receive a reward; for a wide opening, they had to poke a port on the right side.

The researchers then divided the rats into encoders and decoders. The decoders were trained to associate stimulation pulses with the left reward poke as the correct choice, and an absence of pulses with the right reward poke as correct. During trials in which the encoder detected the opening width and transmitted the choice to the decoder, the decoder had a success rate of about 65 percent, significantly above chance.

To test the transmission limits of the brain-to-brain communication, the researchers placed an encoder rat in Brazil, at the Edmond and Lily Safra International Institute of Neuroscience of Natal (ELS-IINN), and transmitted its brain signals over the Internet to a decoder rat in Durham, N.C. They found that the two rats could still work together on the tactile discrimination task.

"So, even though the animals were on different continents, with the resulting noisy transmission and signal delays, they could still communicate," said Miguel Pais-Vieira, PhD, a postdoctoral fellow and first author of the study. "This tells us that it could be possible to create a workable, network of animal brains distributed in many different locations."

Nicolelis added, "These experiments demonstrated the ability to establish a sophisticated, direct communication linkage between rat brains, and that the decoder brain is working as a pattern-recognition device. So basically, we are creating an organic computer that solves a puzzle."

"But in this case, we are not inputting instructions, but rather only a signal that represents a decision made by the encoder, which is transmitted to the decoder's brain which has to figure out how to solve the puzzle. So, we are creating a single central nervous system made up of two rat brains," said Nicolelis. He pointed out that, in theory, such a system is not limited to a pair of brains, but instead could include a network of brains, or "brain-net." Researchers at Duke and at the ELS-IINN are now working on experiments to link multiple animals cooperatively to solve more complex behavioral tasks.

"We cannot predict what kinds of emergent properties would appear when animals begin interacting as part of a brain-net. In theory, you could imagine that a combination of brains could provide solutions that individual brains cannot achieve by themselves," continued Nicolelis. Such a connection might even mean that one animal would incorporate another's sense of "self," he said.

"In fact, our studies of the sensory cortex of the decoder rats in these experiments showed that the decoder's brain began to represent in its tactile cortex not only its own whiskers, but the encoder rat's whiskers, too. We detected cortical neurons that responded to both sets of whiskers, which means that the rat created a second representation of a second body on top of its own." Basic studies of such adaptations could lead to a new field that Nicolelis calls the "neurophysiology of social interaction."

Such complex experiments will be enabled by the laboratory's ability to record brain signals from almost 2,000 brain cells at once. The researchers hope to record the electrical activity produced simultaneously by 10-30,000 cortical neurons in the next five years.

Such massive brain recordings will enable more precise control of motor neuroprostheses—such as those being developed by the Walk Again Project—to restore motor control to paralyzed people, Nicolelis said.

The Walk Again Project recently received a $20 million grant from FINEP, a Brazilian research funding agency, to allow the development of the first brain-controlled whole-body exoskeleton aimed at restoring mobility in severely paralyzed patients. A first demonstration of this technology is scheduled for the opening game of the 2014 Soccer World Cup in Brazil.

Related Stories

Unlocking the secrets of our compulsions

Dec 08, 2010

Researchers have shed new light on dopamine's role in the brain's reward system, which could provide insight into impulse control problems associated with addiction and a number of psychiatric disorders.

Israeli researchers create artificial rat cerebellum

Sep 28, 2011

(Medical Xpress) -- Taking another step towards creating devices that could be meshed with brain function to help those with brain damage, or perhaps one day, to improve on abilities, researchers at Tel Aviv ...

Recommended for you

Surprising new role for calcium in sensing pain

8 hours ago

When you accidentally touch a hot oven, you rapidly pull your hand away. Although scientists know the basic neural circuits involved in sensing and responding to such painful stimuli, they are still sorting ...

Neurons in human skin perform advanced calculations

Sep 01, 2014

Neurons in human skin perform advanced calculations, previously believed that only the brain could perform. This is according to a study from Umeå University in Sweden published in the journal Nature Ne ...

Memory in silent neurons

Aug 31, 2014

When we learn, we associate a sensory experience either with other stimuli or with a certain type of behavior. The neurons in the cerebral cortex that transmit the information modify the synaptic connections ...

User comments

Adjust slider to filter visible comments by rank

Display comments: newest first

SoylentGrin
5 / 5 (6) Feb 28, 2013
...holy cow. This technology is further than I thought. I guess I blinked too long or something.
Tausch
1 / 5 (2) Feb 28, 2013
A pattern (signal) is recognized (decoded) with 100% certainty when the noise (carrier)is identical in both bio-entities.

In decision making (recognizing), the noise (carrier) determines the outcome.

If this is so, what significance does a signal (pattern) have? To shape the noise (carrier).

78% pattern recognition is quite modest. De-emphasizing the signal and 'predicating' the noise leads to (theoretically) 100% pattern recognition.

Making noise identical sounds paradoxical. (Making noise no longer random.) The apparent paradox is a fictional one.
travisr
5 / 5 (5) Feb 28, 2013
The interesting part of this is that this peers down into science fiction more than any other article I've ever read on this site. While the technology is shaky, I believe this has the chance of changing the very fundamentals of society. The ethical questions this brings to mind immediately are topics like becoming beings beyond the body, a type of immortality, super-human intelligence, telepathy, and overall a level of connectedness that could not be rivaled.

Again it's a small start, but imagine the fidelity and advancement in 15-20 years if this is pursued aggressively...

What an exciting time we are a part of...
Donutz
5 / 5 (1) Feb 28, 2013
Resistance is futile. You will be assimilated.
fmfbrestel
5 / 5 (4) Feb 28, 2013
I feel a little like being "that" guy today, so I'm going to be the one to say it: Porn. Think about it.
Tausch
1.7 / 5 (3) Feb 28, 2013
An object which has had all its component parts replaced remains fundamentally the same object. - Ship of Theseus

My antimatter self and I have the same thoughts.
If you do not accept this, then rewrite physics.

A thought has no sense of ownership.
(No ethics here - having thoughts indistinguishable from any thought having less character than the character of god is a thought, not an act of god or nature.)

Quantum information theory.
No Hide.
No Clone.
No Delete.

This guarantees that thought (information) was never created, destroyed, copied, or lost.

Your 'science fiction' has biblical age.
And has no bearing on the reality nature provides.

Yes. We will experience a universe without rivalry.
You get a five. I recognize your state. A changing state.

antialias_physorg
5 / 5 (2) Mar 01, 2013
The ethical questions this brings to mind immediately are topics like becoming beings beyond the body, a type of immortality, super-human intelligence, telepathy, and overall a level of connectedness that could not be rivaled.

The interbrain/intermind as succssor of the internet? Sounds interesting (but also a little bit scary)
the researchers placed an encoder rat in Brazil, at the Edmond and Lily Safra International Institute of Neuroscience of Natal (ELS-IINN), and transmitted its brain signals over the Internet to a decoder rat in Durham, N.C.

I wonder what protocol they used. Probably an unencrypted one for the first test. I wonder how hard it would be to hack such a signal. Thought-injection, anyone?

Tausch
4 / 5 (1) Mar 01, 2013
..how hard...to hack... such a signal.AP

lol
Half as hard as an encrypted one. Without detection. Because you underestimated the impossible.
rko_pec
not rated yet Mar 03, 2013
Wonder what results would look like with different schedules of reinforcement
gmungra
not rated yet Mar 08, 2013
1. I wonder if the decoder rat was really only decoding or also learning. After a learning period the decoder rat could have just remembered which lever to pull for his reward. I suspect that the decoder rat was also remembering, as part of the normal neural process in any brain.
2. But the behavior of the encoder rat based on the communication feedback would still demonstrate proof a paired brain interaction.