Interspecies telepathy: human thoughts make rat move

Video: Human moves rat tail using thoughts alone

Telepathic control of another person's body is a small step closer. By linking the technologies of two brain/computer interfaces, human volunteers were able to trigger movement in a rat's tail using their minds.

Recently, researchers linked the brains of two rats so that they worked together to accomplish a task. Such techniques are unlikely to be applied to humans any time soon because they require invasive surgery to implant electrodes into the brain.

Now Seung-Schik Yoo of Harvard Medical School in Boston and colleagues have created a system that connects a human to a rat via a computer, without the need for the human or the rat to have brain implants.

The human volunteers wore electrode caps that monitored their brain activity using electroencephalography (EEG). Meanwhile, an anaesthetised rat was hooked up to a device that made the creature's neurons fire whenever it delivered an ultrasonic pulse to the rat's motor cortex.

Feeling twitchy

When monitoring the human's brain activity, the researchers looked for a specific EEG pattern known to correspond to visual stimulation. As the volunteers watched a strobe light blinking on a computer screen, the EEG wave synchronised to match the frequency of the strobe (see the "SSVEP" line on video, above).

But when they switched to concentrating on moving the rat's tail, the change in their focus disrupted the EEG, triggering a signal to be sent to the computer. The computer translated this signal into an ultrasonic pulse, which stimulated the rat's motor cortex, causing its tail to move. Using this system, all six of the volunteers were able to trigger movement in the rat's tail with little difficulty.

Yoo says it should be possible for two humans to use a similar system in the foreseeable future. Such a system could, for instance, be used to help a paralysed person relearn to use their limbs by having their therapist initially move them with their mind.

Reality check

But Ricardo Chavarriaga at the Swiss Federal Institute of Technology (EPFL) in Lausanne and others say that while the experiment is an interesting application of the two technologies, linking them together does not reveal much about the ability to link two brains.

Because the rat was anaesthetised to isolate the effect of the intervention, he says it is not clear that the experiment realistically models what would happen if a conscious brain was stimulated this way.

More importantly, Chavarriaga says, the experiment will not be meaningful until the human's intention corresponds with the rat's action. For instance, a person might imagine moving their left hand to move the rat's left paw. Yoo's approach would not be of any use for that because it only tells us that a person's mental focus has changed, not what the thought or sensation behind the change is.

Yoo says his group is working on this now, testing other brain activity patterns and monitoring technologies that may convey more information about a person's thoughts and sensations.