A recent scientific study has opened up promising prospects for those who have lost their sense of touch as a result of nervous system injuries, after proving the possibility of restoring part of this sense by sending precise electrical pulses to the brain.
The study, conducted by researchers from the Universities of Pittsburgh and Chicago and published in the journal Science Translational Medicine, showed that micro-stimulation within the cerebral cortex has a high degree of long-term safety, a step forward in the development of devices that help people with paralysis or spinal cord injuries regain their sense of touch.
The study included five volunteers with spinal cord injuries who received approximately 168 million brain stimulation pulses via implanted brain-computer interfaces over a total follow-up period of 27 years, without any serious side effects being recorded. This is the first and longest-term study of its kind to evaluate the safety of this type of stimulation in humans.
Robert Gont, associate professor of physical medicine and rehabilitation and a member of the Rehabilitation Neuroengineering Laboratory at the University of Pittsburgh, said the study's findings confirm the safety and effectiveness of using brain-computer interfaces to transmit the sense of touch, and pave the way for their future use in homes, not just in medical centers.
This technology involves implanting tiny electrodes in specific areas of the brain, then sending electrical pulses that stimulate nerve cells to generate a sensation that mimics touch, in a step that is an essential part of developing brain-computer interfaces aimed at helping people regain movement, sensation, and communication.
The researchers concluded that impulses directed to the area responsible for the hand in the somatosensory cortex generate a sensation that remains confined to the hand and does not spread to other areas of the body even after years of use.
The results also showed that the sensation persisting after the stimulation stopped was extremely rare, with researchers recording approximately one case per 23,000 stimulation trials. Most of these cases lasted no more than ten seconds and were neither painful nor did they require any medical intervention.
Although the efficiency of the electrodes gradually decreased over time, about 64% of them continued to function efficiently on average, including 60% of the electrodes in one participant ten years after implantation, although a faster decline in their performance was observed during the final stage of the study.
Work on this technology dates back more than a decade, with a team from the University of Pittsburgh successfully enabling a paralyzed individual to control a robotic arm in 2012 using electrodes implanted in their motor cortex. Three years later, researchers restored the sense of touch by stimulating the sensory cortex, before the University of Chicago joined the project and implanted electrodes in both the motor and sensory cortices of its first participant in 2020.
Charles Grinspoon, an assistant professor of neurosurgery at the University of Chicago, said the study's findings indicate that this technology is no longer just a tool used in laboratories, but is nearing the point of becoming a device that patients can use for extended periods in their homes.
Researchers believe that the importance of these results is not limited to restoring the sense of touch, as the same stimulation techniques are currently being tested in brain regions responsible for vision and hearing, which may pave the way in the future for developing devices that help restore other senses in people who have lost them.
The research teams at the Universities of Pittsburgh and Chicago are continuing to develop this technology by improving the nature of the sensation produced by the stimulation to be closer to natural sensation, along with enhancing the performance of the devices and simplifying their adjustment mechanism, which will facilitate their wider use in the future.
