Restoring the Sense of Touch Using a Sensorimotor Demultiplexing Neural Interface: ‘Disentangling’ Sensorimotor Events During Brain-Computer Interface Control

Abstract

Rationale Paralyzed muscles can be reanimated following spinal cord injury (SCI) using a brain-computer interface (BCI) to enhance motor function alone. Importantly, the sense of touch is a key component of motor function. Simultaneously restoring the sense of touch and movement would meet functional needs for BCI users that seek to enhance upper limb function following SCI. Methods The study met institutional requirements for the conduct of human subjects and is registered on the http://www.ClinicalTrials.gov website (identifier: NCT01997125). The participant was a 27-year-old male with stable, non-spastic C5 quadriplegia resulting from a cervical SCI. The participant underwent implantation of a 96 channel Utah microelectrode recording array (Blackrock Microsystems, Inc.; Salt Lake, Utah) in his left primary motor cortex. The hand area of motor cortex was identified preoperatively by fusing functional magnetic resonance imaging (fMRI) activation maps obtained while the participant attempted movements co-registered to the preoperative planning MRI. During experiments, the participant was either completely blinded to the experimental conditions or given brief instructions to complete the necessary actions. Cue and trial parameters were randomized as needed. Results Results are adapted from (Ganzer PD, Colachis 4th SC, Schwemmer MA, Friedenberg DA, Dunlap CF, Swiftney CE, Sharma G in Restoring the sense of touch using a sensorimotor demultiplexing neural interface. Cell 2020). We demonstrate that a human participant with a clinically complete SCI can use a BCI to simultaneously reanimate both motor function and the sense of touch, leveraging residual touch signaling from their own hand. In primary motor cortex (M1), residual subperceptual hand touch signals are simultaneously demultiplexed from ongoing efferent motor intention, enabling intracortically controlled closed-loop sensory feedback. Using the closed-loop demultiplexing BCI almost fully restored the ability to detect object touch, and significantly improved several sensorimotor functions. Conclusion These results demonstrate that subperceptual neural signals can be decoded from human cortex and transformed into conscious perception, significantly augmenting function.