Exoskeletons for Mobility after Spinal Cord Injury: A Personalized Embodied Approach

Abstract

Endowed with inherent flexibility, wearable robotic technologies are powerful devices that are known to extend bodily functionality to assist people with spinal cord injuries (SCIs). However, rather than considering the specific psychological and other physiological needs of their users, these devices are specifically designed to compensate for motor impairment. This could partially explain why they still cannot be adopted as an everyday solution, as only a small number of patients use lower-limb exoskeletons. It remains uncertain how these devices can be appropriately embedded in mental representations of the body. From this perspective, we aimed to highlight the homeostatic role of autonomic and interoceptive signals and their possible integration in a personalized experience of exoskeleton overground walking. To ensure personalized user-centered robotic technologies, optimal robotic devices should be designed and adjusted according to the patient's condition. We discuss how embodied approaches could emerge as a means of overcoming the hesitancy toward wearable robots.

Keywords: body image; body representation; cardiovascular; embodiment; exoskeleton; interoception; pain; spinal cord injuries; taVNS.

Figure 1

Embodiment and body ownership examples. (A1) Hand-related neuronal populations that normally react only to visual stimuli near the hand (A2) after repeated tool use and show similar activation patterns for the area surrounding the tool. (B) The classic rubber hand illusion show how artificial objects, using proper stimulation procedures, can be experienced as part of our own body. (C) The appropriate combination of training and features of prosthetic devices can lead to their integration into body representations, allowing for effective interaction with one’s body and environment.

Figure 2

taVNS stimulation of the auricular branch of the vagus nerve (VN) projects to the nucleus tractus solitari (NTS), continuing to the locus coeruleus and parabrachial nucleus. From the parabrachial nucleus, it propagates to various subcortical and cortical brain regions. HTh: hypothalamus; PBN: parabrachial nucleus; LC: locus coeruleus; NTS: nucleus tractus solitary; DMNV: dorsal motor nucleus of the vagus nerve.