Scientists at Duke University wired the brains of adult rhesus macaque monkeys to form a network, or "brainet," and observed them in their separate rooms as they were each given partial control over a virtual arm they could see on a screen.
When the animals worked together, they were able to synchronize their brain activity to guide the arm of an avatar, allowing them to reach for a virtual ball. Their reward was a small drink of juice.
One monkey acting alone could not move the arm in three dimensions, but three working together could control the 3D movements and reach the moving target.
The monkeys were connected only to a computer, but not one another.
However, in a second set of experiments, the team directly wired the brains of four rats together, and to a computer, to allow the animals to transmit neural brain activity to each other.
The team outfitted the animals with multi-electrode arrays in the motor and somatosensory (sense of touch) cortices to capture and transmit their brain activity.
The rats were able to recognize patterns in brain activity and a "brain-to-brain interface" was established.
Solved weather problems
Some of the input, or stimulation, represented data that included temperature and barometric pressure. The rats were then encouraged, through a reward system, to solve a simple weather forecasting problem, such as whether it might rain.
The researchers observed that the rat "brainet" could perform at the same level or better than one rat on its own.
Duke scientists say the results support earlier claims that brainets "may serve as test beds for the development of organic computers created by the interfacing of multiple animal brains with computers."
Lead researcher Duke University Medical Center neurobiologist Miguel Nicolelis reported on the first direct brain-to-brain interface between animals two years ago.
After experimenting with brain-to-machine interfaces for several years, he and his colleagues found the brain was much more plastic than they had thought.
Scientists said that with practice, the monkeys were easily able to mentally controlled two out of three dimensions of the virtual arm.
Applications for disabled people
The Duke researchers have previously built BMIs (brain-machine interfaces) to capture and transmit the brain signals of individual rats, monkeys, and even human subjects to artificial devices.
"This is the first demonstration of a shared brain-machine interface, a paradigm that has been translated successfully over the past decades from studies in animals all the way to clinical applications," said Nicolelis.
The experiments were described in two articles published in Thursday's issue of Scientific Reports.
Nicolelis said the experiments may help neurologically disabled people regain or improve motor skills.
The Brazilian neurobiologist was part of a team of researchers who created a mind-controlled robotic exoskeleton worn by Juliano Pinto as the paraplegic man took part in the kick-off for the 2014 World Cup in Sao Paulo.