Sense of Touch Can Be Returned to Spinal Cord Injury Victims

The lack of sensation that accompanies paralysis is an additional burden that has, until now, been a problem that science has not been able to remedy.
 
For the first time, a team of scientists, doctors and researchers led by Battelle and The Ohio State University Wexner Medical Center have demonstrated that a person with a clinically complete spinal cord injury (SCI) can use a brain-computer interface (BCI) to simultaneously reanimate both motor function and sense of touch by using residual touch signaling from his own hand. The findings are reported in the scientific journal Cell.
 
The breakthrough came from analysis of years of data collected from NeuroLife program study participant Ian Burkhart, who suffered a spinal cord injury in 2010 when diving into the ocean, and now lives with paralysis in his hands and legs. “When the chip was placed on the surface of Ian’s motor cortex in 2014, it was not known that the signals related to object touch could be observed because of the paralysis,” said lead author and Battelle Principal Research Scientist Patrick Ganzer. “Furthermore, Ian has a very severe SCI that should essentially block hand touch signals from even reaching the brain.” 
 
However, analysis has shown that subperceptual touch following a spinal cord injury affects Burkhart’s motor cortex even though there is essentially a block from the nerves in his arms and their connection back to the brain. Importantly, this subperceptual signal can be detected in the brain, rerouted via the brain-computer interface and sent back to a wearable haptic system to restore the sense of touch. “It has been amazing to see the possibilities of sensory information coming from a device that was originally created to only allow me to control my hand in a one-way direction,” said Burkhart.
 
Medical technologies like these that provide both movement and sensation back to their users has the potential to improve independence. “Helping people to become more whole again and less dependent on caregivers is a major step in improving quality of life,” said Justin Sanchez, who is a Battelle Life Sciences Technical Fellow.
 
Battelle’s NeuroLife team is currently working toward a take-home BCI system for individuals with tetraplegia that addresses user needs by leveraging the knowledge gained in a five-year clinical study. The goal is to provide technology options to these individuals to improve their everyday lives.
 
“This work represents an important milestone in the development of BCIs for restoring hand functions after SCI,” said Douglas Weber, co-investigator and associate professor of Bioengineering at the University of Pittsburgh. “Ian has demonstrated that by recovering even simple touch sensations, his ability to control his hand through BCI improves dramatically.”
 
Dr. Keith Tansey, professor of Neurosurgery and Neurobiology at the University of Mississippi Medical Center and past president of the American Spinal Injury Association, said the work is important for people who have a spinal cord injury, and for those who care for them. “In this proof of principle report, the authors have leveraged on a rarely appreciated aspect of spinal cord injury to provide a novel and important advancement in neurological functioning using a brain-computer interface. The notion that clinical completeness in spinal cord injury is very often neurophysiologically ‘discomplete’ acknowledges that activity in residual neural circuitry, in this study specifically ascending sensory pathway signals, can be detected and utilized to both augment motor function but also to restore sensory perception from below the level of injury.”
 
Other important findings:

• Regarding active touch, Burkhart cannot detect touching small objects (e.g., shape of a pencil), and is essentially guessing if he is touching larger objects. A computer can be trained to reliably detect subperceptual active touch (using AI / machine learning). When the computer detects subperceptual active touch, it triggers haptic feedback on skin that Ian can feel.
• During real-time BCI operation, touch and movement signals can be reliably separated, or demultiplexed. Using this capability, Burkhart can simultaneously control multiple devices with his brain (haptic feedback sleeve on the arm). This finding leads to improvements in BCI system speed and Burkhart’s overall upper limb function.
• Touch signals from Ian’s brain can also be used to automatically control his grip intensity (so fragile objects are not crushed, and heavy objects are gripped appropriately). It allows Burkhart to multi-task and relieves him from the burden of constantly looking at his hand and thinking of movement for long durations during object manipulation.