Telepathy is near: rat brains were connected for the first time, in a breakthrough "telepathy" experiment that allowed two rats to directly share brain signals through an online electronic link across continents.

The scientists behind the project made science fiction a reality, creating an unprecedented rat-brain interface that allowed the rats to transmit "thoughts" to each other through brain implants so that one rat could help the other instantly solve puzzles.

This might seem unbelievably enough like telepathy, but the two mind-connected rats were not even in the same place - one was in Brazil and the other was thousands of miles away in North Carolina. The signals from one rat brain implant to the other were transmitted through the Internet.

The rat-brain-interface worked by first training an "encoder" rat in a behavioral task that required it to choose between two choices of tactile or visual stimuli by pressing one of two levers. One of the choices gave the rat a reward of water, and with practice the encoder rat learned to make the correct selections that delivered rewards.

A brain implant recorded neural signals from the encoder rat's motor and somatosensory cortices (the brain areas involved in movement and touch), and transmitted the signals electronically to a similar electrode implant in the same regions of the "decoder" rat brain.

The decoder rat in Brazil, receiving brain signals "telepathically" from the encoder rat in North Carolina through a computer, learned to press the same levers when given the behavioral task even though it had never been trained before.

The rats even learned to share information both ways. Initially, the encoder rat was rewarded for performing its own task correctly. The encoder rat was then given larger rewards when the decoder also made the right choice, so when the decoder got the task wrong, the encoder would move more accurately the next time so its brain activity became clearer for the decoder the next time.

Overall, the decoder rat pressed the right lever in the task seven out of 10 times - not as successful as the 95% accuracy of the encoder rats, but still far better than chance.

You can watch a video explaining the rat brain "telepathy" study, which was published in Scientific Reports on February 28, on Youtube:

 

The experiment was led by Duke neuroscientist Miguel Nicolelis, a pioneer of brain-machine interfaces (BMIs). Nicolelis's team first created international waves in neuroscience in 2011, when his team created a brain-machine interface that allowed a monkey to control a robotic arm with its thoughts through an Internet-linked brain implant. Earlier this month, Nicolelis led a project that rewired rat brains to detect infrared light through their sense of touch.

The groundbreaking experiment marks a major progression in the field, allowing the real-time sharing of neural sensorimotor information between two living beings in a feat that, to the layman, sounds just like telepathy.

It's unclear how the decoder rats combined their natural sensory observations with the virtual information from their brain implants, which is an aspect Nicolelis plans to investigate in future work.

The system is not quite the same as telepathy: "It's not the Borg," said Nicolelis to Nature's Ed Yong. "But we created a new central nervous system made of two brains."

Nicolelis believes that this rat brain-to-brain interface is the first step towards the creation of an "organic computer" that uses linked animal brain networks to solve tasks. Far before actual telepathy exists, a more immediately foreseeable application could be to rehabilitate damaged human brains of people who have lost sensorimotor function after strokes or movement disorders.

Some neuroscientists are unfazed by the experiment, playing down claims that telepathy is at hand.

Lee Miller, a physiologist at Northwestern University, told Nature that the current paper is like a "poor Hollywood science-fiction script," and that it's unclear "to what end the effort is really being made."

Andrew Schwartz, a neurobiologist at the University of Pittsburgh, added:

"Although this may sound like 'mental [telepathy]', it was a very simple demonstration of binary detection and binary decision-making," he says. "To be of real interest, some sort of continuous spectrum of values should be decoded, transmitted and received."

Among his supporters is Ron D. Frostig, a neuroscientist at the University of California, Irvine. "I think it's an amazing paper," said Frostig to the New York Times, describing it as a "beautiful proof of principle."

"We can't yet say how this will help people," Frostig added to Slate. "But this is the first time that it's been proven that something like this can be done at all. I think it's wonderful."

Meanwhile, Nicolelis is already working on extending the rat brain-to-brain interface to link four rat brains, and plans to start the even more groundbreaking project of connecting the brain activity of paired monkeys in a virtual game.

"Rats don't have a sense of self so it's hard to say what the effect on the animals are," said Nicolelis to Nature, "but monkeys can collaborate in a much more complex way."

He envisions a kind of monkey "Second Life," which sounds even more like telepathy:

"We are now working with monkeys and training them in pairs to control [computer-generated] body avatars," he told the Guardian. "They will meet in a virtual space and learn to play a game. They'll have to share the rules by direct brain-to-brain interaction, and combine their brain activity to complete the game."

As researchers develop brain-machine interfaces that transmit increasingly complex information, Nicolelis expects to eventually see a kind of human telepathy "brain net" in the future, if not in his lifetime.

He explains in his book "Beyond Boundaries" that such a brain-machine connection would enable multiple, interconnected human brains to work collectively to solve problems - like the Internet, but with your brain directly connected.

That sounds as ethically complicated as it is ambitious. Christopher James, an expert on computer-brain interfaces at Warwick University in the United Kingdom, said that multi-human brain interfaces would not be practically or ethically appropriate in the foreseeable future, whether they're as simple as the one in Nicolelis's experiment or can actually be called telepathy.

"The system would require placing invasive electrodes in participants and the visual and tactile brain signals involved are quite crude," James told CNN. "You could not exchange abstract thoughts."

It's likely that Nicolelis is already looking to transmit more complicated signals than just visual and tactile thoughts. Even if communicating abstract human thoughts through electronic telepathy is far in the future, it's clear that technological change with brain-machine interfaces is happening much sooner than we expect, with rat brains and other animals.

"We cannot predict what kinds of emergent properties would appear when animals begin interacting as part of a brain-net," Nicolelis said in a statement. "In theory, you could imagine that a combination of brains could provide solutions that individual brains cannot achieve by themselves."