Distributed Transcutaneous Electrical Stimulation - Novel Method for Inducing Proprioceptive Illusions
Abstract
Proprioceptive feedback plays a crucial role in motor control, especially in absence of visual feedback and/or tactile feedback. Unfortunately, many people suffer from lack of proprioception by physical injuries or neurodegenerative diseases. Prosthetic limb and telerobotic users also experience proprioceptive mismatch, which limits the control accuracy and intuitiveness. To address the proprioceptive deficit, several invasive and non-invasive approaches have been introduced, via vibration, invasive electrical stimulation, and skin stretch. However, compensating proprioceptive deficit is still challenging as the current solutions have limitations in terms of effectiveness, usability, and consistency.
In this study, we proposed a new way of proprioceptive modulation using transcutaneous electrical stimulation. We hypothesis that transcutaneous electrical stimulation on elbow flexor muscles will augment the spindle afferent and induce illusion of elbow joint extension. Eight human subjects participated in the study to test the hypothesis. We first identified the best location of electrodes to induce the proprioceptive illusions of elbow joint angle, as one electrode on the belly of biceps brachii short head and another on the distal tendon of brachioradialis. Based on the results of two arm matching test and Pinocchio illusion test, we found that 6 of 8 subjects experienced illusion of elbow joint extension by transcutaneous electrical stimulation, which supports our hypothesis. On average, they reported 7.1° angular illusion of elbow joint extension and 1.5x increase of nose height at Pinocchio illusion test. However, 2 of 8 subjects reported illusion of elbow joint flexion by the same transcutaneous electrical stimulation, which falsifies our hypothesis. We interpret this contradictory result as, transcutaneous electrical stimulation can either augment or interfere (i.e., add noise) muscle spindle afferent signal. Note that, the direction of proprioceptive illusion was consistent per subject, and the effect of proprioceptive illusion was clear for all subjects. This result suggests that, transcutaneous electrical stimulation may shed a light to address limitations of current approaches of providing proprioceptive information, by improving effectiveness, usability, and consistency.
Citation
Rangwani, Rohit (2020). Distributed Transcutaneous Electrical Stimulation - Novel Method for Inducing Proprioceptive Illusions. Master's thesis, Texas A&M University. Available electronically from https : / /hdl .handle .net /1969 .1 /191835.