Karl Zimmer in the NYTimes (emhasis mine):
Dr. Nicolelis and his colleagues began by implanting two sets of electrodes in the brains of four rats. One set delivered a signal into one part of each brain, while the other eavesdropped on a different brain patch.
The four rats received the same signal, and then a computer monitored how their brains responded. If all four rats produced synchronized signals in their brains, they were rewarded with a sip of water.
Through trial and error, the rats learned how to consistently synchronize their brains, making it possible for the rats to act like a simple computer. In one experiment, the animals learned how to produce different brain responses to two different signals: a single burst of electric pulses, or four bursts.
The rats learned how to produce synchronized brain activity in response to one of the signals, and unsynchronized activity in the other. Their collective response was correct as often as 87 percent of the time — substantially better than an individual rat learning on its own.
And of course monkeys can do it:
Dr. Nicolelis and his colleagues then turned from rats to monkeys, with a new twist on earlier experiments in which individual monkeys learned to control a robot arm. This time the scientists implanted electrodes into two monkeys instead of one.
Each monkey looked at a computer screen on which there were images of an arm and a ball. The computer combined the brain signals from both monkeys to move the arm. The two monkeys learned to work together to reliably move the arm to the ball, which produced a reward.
In another trial, one monkey learned to control the horizontal movement of the arm while the other monkey controlled its vertical movement by means of electrical brain impulses. In an even more ambitious test, the scientists programmed a virtual arm in three-dimensional space, allowing three monkeys to share control of different aspects of its movement.
Once again, the monkeys learned to move the arm to the ball. Even when one of the monkeys did a bad job of controlling the arm, the other two compensated to keep it on track.
Think about shared culture in the context of this remark:
Dr. Nicolelis speculated that our brains can naturally join together when we share the same experiences. “When people are watching television — millions of people watching the same images — we may be synchronizing millions of brains,” he said.