A sensorimotor neural interface successfully restored touch sensation in a patient with quadriplegia resulting from spinal cord injury (SCI), researchers report.
“Neurotechnology and brain-computer interfaces are becoming an effective way to leverage residual neural signals for functional benefit following SCI, stroke, and several other dysfunctional states,” Dr. Patrick D. Ganzer of Battelle Memorial Institute, in Columbus, Ohio, told Reuters Health by email.
An estimated 50% of patients with a clinically complete SCI have a “sensory discomplete” SCI, where tactile stimuli that the patients cannot feel nevertheless evoke changes in cortical activity. Brain-computer interfaces (BCIs) can reanimate paralyzed muscles after SCI, but whether they can restore touch was unknown.
Dr. Ganzer and colleagues used a BCI could to simultaneously reanimate both motor function and touch sensation in a chronically paralyzed patient with a clinically complete SCI who could already use a BCI to move the hand.
While the patient was unable to perceive mechanical sensory stimuli below spinal level C6, sensory stimuli to the hand robustly modulated neural activity in the contralateral primary motor cortex (M1).
This residual sensory neural activity was reliably decoded from M1 using a support vector machine (SVM), and a vibrotactile array on the affected bicep enabled sensory feedback that restored conscious touch perception to a detection rate over 90%.
A modified grasp and release test demonstrated real-time sensorimotor demultiplexing where the participant was able to perform the task using the system but not without using the system, the team reports in Cell.
“It was initially surprising when we first discovered the subperceptual touch signal,” Dr. Ganzer said. “The participant has a very severe spinal cord injury that could have blocked this signal traveling from the hand to the brain. These results demonstrate that even a small contingent of spared spinal fibers can be leveraged for functional benefit. Lastly, the study’s overall results are interesting because the brain implant was not originally intended to record both touch and movement neural signals.”
