Story highlights Rats have collaborated telepathically from U.S. to Brazil in experiment

First use of neurotechnology to transmit thoughts directly between animal brains

experiments could lead to the creation of a biological computer -- or "brain-net"

Results of linking of multiple brains published in the journal Scientific Reports

Rats have collaborated telepathically across continents in the first use of neurotechnology to transmit thoughts directly between animals' brains.

Scientists trained rats in Durham, North Carolina and Natal, Brazil to work together to solve problems in return for a drink of water. In the first experiment they had to press the correct lever corresponding to a particular indicator light; in the second they had to distinguish between wide and narrow openings.

Electrodes picked up the brain activity of the first rat, the "encoder", and fed it over the internet into the brain of its partner, the "decoder", which had the same levers in its cage but received no visual cues about which one to press. The best decoder rats correctly mimicked their corresponding encoder partners 70 per cent of the time.

Miguel Nicolelis, a pioneer of research into brain-computer interfaces at Duke University in North Carolina, worked on the experiments with scientists at the Safra International Institute for Neuroscience of Natal in his native Brazil. Their results were published on Thursday in the journal Scientific Reports.

Prof Nicolelis said the experiments could lead to the creation of a biological computer -- or "brain-net" -- linking multiple brains. "We cannot even predict what kinds of emergent properties would appear when animals begin interacting as part of a brain-net," he said. "In theory, you could imagine that a combination of brains could provide solutions that individual brains cannot achieve by themselves. One animal might even incorporate another's sense of self."

The collaboration worked not only when both rats were in the same lab, but also when one was at Duke and the other in Brazil. "Even though the animals were on different continents, with the resulting noisy transmission and signal delays, they could still communicate," said Miguel Pais-Vieira, another member of the team. "This tells us that we could create a workable network of animal brains distributed in many different locations."

Previous research has shown that visual and tactile information can be fed into and out of a rat's brain using microscopic electrodes implanted in the cortex -- most recently when the animals learnt to "feel" invisible infrared radiation.

In Prof Nicolelis' first experiment, the encoder rat got a bigger reward if the decoder also made the right choice, leading to two-way neural collaboration between the two rats. "We saw that when the decoder rat committed an error, the encoder basically changed both its brain function and behaviour to make it easier for its partner to get it right," he 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."

In the second experiment, a scan of the decoder's brain showed that it began to represent the encoder's whiskers as well as its own whiskers in the tactile cortex. "The rat created a representation of a second body on top of its own," said Prof Nicolelis.

Professor Christopher James, an expert on brain-computer interfacing at Warwick University in the UK, said the Duke team's plans for multi-brain networks might work in animals but, for ethical and practical reasons, would not be appropriate for humans in the foreseeable future. "The system would require placing invasive electrodes in participants and the visual and tactile brain signals involved are quite crude," Prof James noted. "You could not exchange abstract thoughts."