Researcher(s)
- Lindsay Munyaka, Biomedical Engineering, University of Delaware
Faculty Mentor(s)
- Fabrizio Sergi, Biomedical and Mechanical Engineering, University of Delaware
Abstract
Methodological limitations have prevented direct in vivo measurement of reticulospinal tract (RST) function in humans. The RST is believed to amplify the long latency response (LLR), a characteristic response observed in stretched muscles, when participants resist an imposed perturbation. Hence employing functional magnetic resonance imaging (fMRI) during robot-induced LLRs under different task conditions could offer a means to assess motor-related RST function. Previous research conducted in the lab led to the development of the Dual Motor StretchWrist (DMSW), a new MR-compatible robotic perturbation system, and validated its functionality via experiments that used electromyography and fMRI. The DSMW evokes LLRs under different task conditions as a way to assess motor-related RST function. This project aimed to (1) comprehensively document the existing DSMW to enhance operator understanding and (2) develop a replica of the DSMW to enable simultaneous data collection across multiple studies. The documentation included a detailed catalog of both the mechanical parts of the DSMW and the control box which contains the electronics utilized to control the robot, an instructional video on the stringing of the robot, and assembly and control box setup documents outlining the process of constructing the DSMW. To validate the functionality of the developed replica, perturbation tests were conducted, during which the two robot motors moved together at 150 deg/s for 200ms. First, the motors were tested while connected to the robot transmission. Next, the robot was tested with a passive hand, and finally, with a hand applying a 0.2Nm background torque before the participant was asked to either “yield” or “resist” the perturbation. The maximum difference in position between the two motors during all tested perturbations was 0.360 deg, within the ±1 deg tolerance required to validate functionality. Thus, we established that the developed replica of the DMSW functions within specifications, and can be used in future studies that aim to elucidate the neural control of human movements.