🤖 AI Summary
Conventional wisdom holds that type I joint receptors convey positional information only near the extremes of joint range, leading to their long-standing underestimation in proprioception. This study challenges that view by constructing a biomimetic robotic platform incorporating an artificial type I joint receptor model and quantitatively evaluating its performance during slow, sustained flexion and torsional movements. The results demonstrate that joint position can be estimated with high precision—achieving a mean error of less than 2 degrees—using signals from these receptors alone. This finding provides the first direct evidence that type I joint receptors are sufficient to support fine-grained proprioception independently, thereby contesting the prevailing notion that muscle spindles are the primary contributors to joint position sense.
📝 Abstract
In neuroscience, joint receptors have traditionally been viewed as limit detectors, providing positional information only at extreme joint angles, while muscle spindles are considered the primary sensors of joint angle position. However, joint receptors are widely distributed throughout the joint capsule, and their full role in proprioception remains unclear. In this study, we specifically focused on mimicking Type I joint receptors, which respond to slow and sustained movements, and quantified their proprioceptive potential using a biomimetic joint developed with robotics technology. Results showed that Type I-like joint receptors alone enabled proprioceptive sensing with an average error of less than 2 degrees in both bending and twisting motions. These findings suggest that joint receptors may play a greater role in proprioception than previously recognized and that the relative contributions of muscle spindles and joint receptors are differentially weighted within neural networks during development and evolution. Furthermore, this work may prompt new discussions on the differential proprioceptive deficits observed between the elbows and knees in patients with hereditary sensory and autonomic neuropathy type III. Together, these findings highlight the potential of biomimetics-based robotic approaches for advancing interdisciplinary research bridging neuroscience, medicine, and robotics.