Coordinated hand movement sensation revealed through an implanted magnetic prosthetic kinesthetic interface.

Muscle contractions to control prosthetic hands do not feel like those to control natural hands because amputation decouples movement sense (kinesthesia) from movement execution. The myokinetic kinesthetic interface (MKkI) uses remote vibration of permanent magnets implanted in amputated forearm muscles to restore kinesthesia. A participant reported coordinated finger movements of hand closing and opening, constrained within physiological bounds, with stereotypical conformations and dynamics. Aggregated unstructured explorations and systematic psychophysics exposed unreported perceptual sensitivity at vibration frequencies that trigger kinesthetic sensations. Complex coordinated grip sensations elicited from single forearm muscles reveal that kinesthetic brain representations are likely rooted in perception of synergistic movement production. By leveraging the natural synergistic features of kinesthesia, the MKkI will help link perception and action to functionally elevate emerging intuitive bidirectional human-machine interfaces.