Authors of the paper accepted to PNAS, "Neural Interfacing Architecture Enables Enhanced Motor Control and Residual Limb Functionality Post Amputation," include: Shriya S. Srinivasan, Samantha Gutierrez-Arango, Ashley Chia-En Teng, Erica Israel, Hyungeun Song, Zachary Keith Bailey, Matthew J. Carty, Lisa E. Freed, and Hugh Herr.
The research was funded by the MIT Media Lab Consortia, the National Institute of Child Health and Human Development of the National Institutes of Health, the National Center for Medical Rehabilitation Research of the National Institutes of Health, and the Congressionally Directed Medical Research Programs of the US Department of Defense.
Persons with amputation face a significant loss in mobility, independence, and quality of life. Neuroprosthetic control offers a solution to address these challenges, but is constrained by current surgical techniques for amputation. To overcome these challenges, the Biomechatronics lab and clinical collaborators have developed the Agonist-Antagonist Myoneural Interface (AMI), a novel surgical amputation paradigm that mimics natural neuromuscular dynamics and enables easier communication between the human body and prostheses.
Over the past few years, we have conducted a clinical trial to compare the level of motor control and sensation afforded by residual limb musculature in persons that have undergone the below knee AMI amputation and persons who have undergone a standard below knee amputation.
We found that the AMI amputation offered people greater motor coordination when compared to traditional amputation, as well as greater precision over a larger range of motion. Our study links this to the mechanistic basis of the AMI through comparisons of muscle activity (electromyography) and muscle strain, indicating a greater ability for proprioceptive sensory feedback.
Additionally, AMI subjects reported higher phantom limb sensation with decreased levels of phantom limb pain. Most importantly, AMI subjects are able to produce neural signals that are much clearer to read from the surface of the skin and be used to control prosthetic robots.
Clinically, decreased phantom limb pain with increased phantom limb sensation indicate improvements in neurological health that are important for patients’ quality of life. Our results significantly influence the improvement of the current amputation stand-of-care while also progressing the usability of neuroprostheses.