Quantitative Biomarkers of Prosthetic Embodiment Based on Rubber Limb Illusion Paradigms

Embodiment, the subjective experience of owning and controlling one's body, is crucial in motor control, rehabilitation, and prosthetic design. Despite its importance, the development of reliable quantitative biomarkers for embodiment remains limited. This study explores quantitative metrics of embodiment using a Rubber Limb Illusion (RLI) paradigm while simultaneously recording electroencephalographic (EEG) activity, heart rate (HR), galvanic skin response (GSR), and pupillometry. Sixteen healthy participants engaged in tasks involving myoelectric prostheses under static, movement, and feedback conditions. Results demonstrated significant modulation of EEG power between conditions: Alpha power in the sensorimotor region was significantly higher in the static and feedback conditions than in movement, suggesting reduced sensorimotor processing during passive sensory input. Frontal beta power followed a similar trend, suggesting lower cognitive load. Autonomic signals revealed increased HR during movement, consistent with greater physical and cognitive demands, while feedback conditions showed moderate engagement. Subjective measures confirmed these results, revealing increased embodiment post-task, particularly in the static condition, and higher mental and physical demands during movement.Clinical relevance- These results seek to establish quantitative biomarkers for embodiment, a key but often overlooked aspect of prosthetic design and rehabilitation. Combining central and autonomic bio-signals provides new insights into assessment tools that can enhance clinical evaluation and improve prosthetic outcomes.