Exploring Synergy Between Tactile Perception and Arm Usage of Stroke Patients: a Pilot Study on Healthy Subjects

Abstract

Stroke causes severe tactile deficiencies, affecting motor control during object grasping and lifting. Understanding the fundamental neural disorders associated with tactile deficits is crucial for developing effective rehabilitation and treatment plans. Previous studies have investigated the dynamics between finger grasping behavior and arm muscle activation in stroke patients. However, the exact neuromuscular synergy between tactile perception and arm usage remains unexplored. In this study, we designed a comprehensive experimental platform and tested potential synergies in 12 healthy young adults, serving as a control group to establish a foundation for future studies on stroke patients. The experimental platform consists of a lever arm on which torques can be applied to the subject's arm. The end effector is equipped with a special ultrasonic friction modulation plate that can reduce apparent friction by up to 63%, simulating real-world grasping tasks in a controlled setting. The experiments were conducted under varying conditions of friction and arm usage. Results indicate significant effects of tactile stimulation on grasping force adaptation (p < 0.05 in 8 of 12 experimental conditions). In contrast, arm usage did not show significant synergy with tactile perception (p = 0.44 for grasping force adaptation amplitude, and p = 0.73 for reflex delay). These findings demonstrate that the experimental platform can provide insights into human tactile behaviors, which is critical for studying the synergy between tactile sensory and motor control. The results will lay the groundwork for future research on underlying pathologies and rehabilitation strategies for stroke patients.