ERI: A Model-Based Approach to Capture Upper Limb Tremor Propagation Mechanisms and Identify Main Tremorogenic Muscles

About This Grant

Tremors are involuntary, rhythmic movements that make daily activities like eating, writing, or dressing very difficult for millions of people, especially those with Parkinson's disease or essential tremor. Current treatments such as medications and surgeries are often not effective because how tremors originate and spread through the body is not completely understood. This project will pinpoint primary tremor-generating muscles and expose how upper limb tremors start and move through muscles and joints of the arm and hand by developing computer models of the human-arm musculoskeletal system. This critical knowledge will inform the design of more effective tremor-reducing devices, such as wearable orthoses or muscle stimulators, ultimately improving quality of life for those affected. The project share findings with the public, develop educational modules for undergraduate courses, and train students to expand a future STEM workforce. These efforts will raise awareness and foster the next generation of scientists and innovators to accelerate new solutions for individuals living with movement disorders. Leveraging musculoskeletal modeling (MSM) and system dynamics approaches, this project will advance the understanding of upper limb tremor propagation mechanisms and identify the key muscles contributing to tremor genesis. Existing models are limited by linear and simplified assumptions, which fail to accurately capture the complex, nonlinear interactions between neural drive, muscle activity, joint displacements, and fatigue. To address these limitations, this research will enrich a publicly available upper limb MSM with muscle-fatigue components that will enable simulations of tremor transmission across the upper limb’s joints and muscles. The work focuses on developing dynamic models of tremorogenic muscles and computer simulations for tremor suppression devices, including wearable orthoses and functional electrical stimulation systems. The research postulates that the interplay between neural signals, muscle activation patterns, and joint mechanics significantly influences tremor propagation and that insights from simulations can guide the design of more targeted, effective intervention devices. This project will employ OpenSim simulations and numerical analysis to identify the principal tremorogenic muscles, elucidate the tremor-fatigue relationship, and develop strategies for tremor reduction. The outcomes will contribute substantially to the field by providing a more accurate, scalable MSM, advancing the mechanistic understanding of tremor disorders, and informing the next generation of neuromuscular therapeutic interventions. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.