Researchers report today in the journal Science Translational Medicine that they'll do something similar: stimulating areas of a human test subject’s brain with electrodes can recreate the perception of touch in a robotic hand.
About 280,000 people in the United States alone are with a spinal cord injury, according to the National Spinal Cord Injury Statistical Center. This season Determined by the severity, damaged nerve connections lead to effects that range from a partial lack of feeling to entire lack of motion in different limbs.
Handle fragile objects such as eggs and to safely socialize with other human beings, more than just control–they should have the ability to change control based on touch comments is needed by individuals.
In the May 2016 issue of IEEE Spectrum technology which allows amputees to feel a robotic arm, prosthesis was, described by Dustin Tyler, head of the Practical Neural Interface Laboratory at Case Western Reserve University in Cleveland. That technique relied on electrically stimulating peripheral nerves using electrodes implanted into the user’s arm. The subtle movement capabilities improved in a robotic arm. But the technology doesn’t work if the link between limbs and brain is absent, such as with spinal cord injuries, Gaunt says.
“We’re going right to the mind,” he says.
In the early 20th century, surgeons began sparking the cortex of the human brain to help treat epilepsy and understand motor function. Research published in Nature in 1997 suggested that animals exposed to electric stimulation in particular regions of the brain respond like their hands were excited, but even with follow-up studies, precisely what creatures feel remained a mystery. In several experiments where scientists electrically stimulated human brains, for example, 2013 research in the Journal of Neural Engineering, participants reported sensations that felt like they were coming in the hands, but described the feelings a more of a buzzing or the tingling sensation, like when your foot falls asleep.
In the new research, Gaunt and his team ran a six-month experiment on a man who suffered a spinal cord injury about ten years earlier. They created a map linking finger sensations and brain regions, which they used to model touch in a robotic hand.
But where to put them?
The researchers began the experiment by monitoring the magnetic fields coming in the brain’s neurons when Nathan Copeland, the test subject, envisioned something touching different parts of his hand. By combining the readings with magnetic resonance imaging, they created a map of groups of neurons in the S1 cortex related to feeling in the thumb, index finger, little finger, and palm.
Directed by the map, the researchers cut into the test subject’s brain, fitting the implants about a sheet of paper away from the neurons that are important. The microelectrode arrays linked up to alloy pedestals that adhered outside his skin for connection to an external electric stimulator.
For the first number of weeks after the surgery, Copeland described tingling in the hands, then after just throughout the entire body. It was caused by random neurons firing, which finally died down.
The team connected Copeland’s implants via cables to some micro stimulation system. They started exciting neurons with small pulses of electricity and tracked the subject’s results.
During stimulation, over the next few weeks, the patient reported variations of shakings, touches, pressure, and tingles that felt as if they occurred at joints and below your skin of hand. The mappings between brain areas and hand senses were pretty consistent over the six months, Gaunt says.
For the test that was grand, they blindfolded the subject and hooked him up into a robotic hand. When they pressed the fingers of the hand, it communicated with the implant, which fired the neurons in the area of the brain corresponding. At first, the patient managed to accurately identify the place about 85 percent of the time. Subsequently, as he got used to it, he reached 100 percent.
The mapping between sensations and brain areas and their place on the hand could be unique to each person. Or they could change day by day, demanding distinct calibration, but “I completely expect it to work in others,” says a Case Western Reserve University neuroengineer who was not involved in the study, Bolu Ajiboye. He’s working on a clinical trial to restore movement, not sense, via microelectrode stimulation of the mind.
There are several limits to the system, Gaunt notes. For one, the evaluation subject described some of the senses as regular but others as electric tingles.
Also, the team can barely duplicate the actions in all parts of the hand the points of fingers. Gaunt suggests that the implant’s electrodes may not have already been placed in quite a perfect area to stimulate the needed neurons.
The research is a “proof of principle,” that “maybe natural perceptions” can appear after stimulation, says Zelma Kiss, a neurosurgeon and specialist in deep-brain microstimulation at the University of Calgary in Alberta, Canada, who was also not involved.
More wires, the more implants, and the more arrays wanted.
Gaunt says his team is currently focusing on exploring how the implant can help with delicate movement tasks alongside a motion control implant as well as improving functionality.
But improvement will probably be slow. “It ’s important to remember that these experiments are hard,” Ajiboye says.