Thought-controlled robot arms: Welcome to the future!

It's the year 2012, and while we don't all have jet packs or flying cars, there have been some pretty incredible scientific discoveries as of late. Two amazing studies in particular have come out involving advances in spinal cord injury rehabilitation. The first helped paralyzed rats to walk again, and in the second a tetraplegic woman used a thought-controlled robotic arm to take her first self-directed sip of coffee in 15 years. The first study, published in Science by a Swiss research group, used rats to study physical rehabilitation in paraplegic animals. The researchers partially severed the spinal cords of a group of rats, paralyzing their hind-legs but crucially sparing some of the nerve tracts up to the brain. They then stimulated the spinal cords of these animals in the affected region with an electro-chemical current, hoping to excite the remaining nerve cells. The idea behind this is that if you can activate somatosensory signals (the sensations of touch and position of the body) in the affected limbs, you can help rewire the brain to potentially encourage firing of motor neurons as well.

Researchers also fitted the rats with a prosthetic harness that helped support the animals and placed them on a tiny treadmill, while simultaneously stimulating their injured spinal cords with the electro-chemical signal (the article has amazing videos of this here). By zapping the spine with this current and artificially moving the animals' legs, it is possible that any lingering neurons involved in these motor and sensory regions will be stimulated, and possibly re-wire to facilitate further repair and improve locomotion. Sure enough, after just three weeks of this training program some of the animals were able to take steps voluntarily, and after six weeks all of the rats could walk with help from the stimulation. After two more weeks of training these formerly paralyzed rats were even able to go up stairs and jump over obstacles!

Confirming the researchers' theory of assisted neurogenesis, the rats who had undergone the training program had significantly more new neurons and connections from the spinal cord to the motor area of the brain than animals who had not been trained.

In the second and even more fantastical study, two patients with tetraplegia (complete paralysis of the body) were able to self-direct a robotic arm using only their thoughts. Led by Dr. Leigh Hochberg at Brown University and published in the journal Nature, scientists implanted an electrode into the motor area of the paralyzed individuals' brains. The patients practiced for months, training the computer chip to read their motor neurons' signals by imagining moving their arms in various prescribed motions. The chip learned to decode the relevant firings from these cells, measuring the corresponding output from each neuron for the specified movement, and then used these signals to comunicate with a computer and direct a nearby robotic arm.

Starting with just simple point and touch actions, the patients trained the system on increasingly more difficult motions involving precise speed, force and direction. By the end of the study, the communication and interpretation of one of the patient's thoughts was so well coordinated she was able to use the robotic arm to grasp a cup, raise it to her lips and drink through a straw (there are some pretty amazing images of this as well).

I'm going to repeat that: with the help of science and a microchip, this woman controlled a robot with her mind!

So while I'm still waiting for my jet pack, these studies are pretty exciting examples of advances in health-science research, showing just how far science has come and giving us a glimpse into the next generation of neuro-engineering. Welcome to the future.

Dana Smith

PhD student in Experimental Psychology at the University of Cambridge