Optimal integration of intraneural somatosensory feedback with visual information: a single-case study

Abstract

Providing somatosensory feedback to amputees is a long-standing objective in prosthesis research. Recently, implantable neural interfaces have yielded promising results in this direction. There is now considerable evidence that the nervous system integrates redundant signals optimally, weighting each signal according to its reliability. One question of interest is whether artificial sensory feedback is combined with other sensory information in a natural manner. In this single-case study, we show that an amputee with a bidirectional prosthesis integrated artificial somatosensory feedback and blurred visual information in a statistically optimal fashion when estimating the size of a hand-held object. The patient controlled the opening and closing of the prosthetic hand through surface electromyography, and received intraneural stimulation proportional to the object’s size in the ulnar nerve when closing the robotic hand on the object. The intraneural stimulation elicited a vibration sensation in the phantom hand that substituted the missing haptic feedback. This result indicates that sensory substitution based on intraneural feedback can be integrated with visual feedback and make way for a promising method to investigate multimodal integration processes.

Quantifying the alignment error and the effect of incomplete somatosensory feedback on motor performance in a virtual brain–computer-interface setup

“…We can infer from our data that the optimal positioning of the end effector probably lies in the range between the translation and the BCI-simulation condition, while some individual variance cannot be excluded. This is supported by research performed by Risso and colleagues, who have shown in a single-case study that integration of both visual and somatosensory information significantly shapes perception 30 . Future research should therefore cover more combinations of rotation angle and displacement to further advise the robot arm placement in BCI-scenarios.…”

A Review of Sensory Feedback in Upper-Limb Prostheses From the Perspective of Human Motor Control

“…However, although these components have been extensively investigated in able-bodied subjects, the literature on how they work in an amputee is nascent. The emerging literature seems to generally confirm what the framework proposesnamely that the computational methods are similar between able-bodied subjects and prosthesis users [e.g., both seem to use Bayesian integration (Risso et al, 2019), internal models (Lum et al, 2014)], but that the parameters (such as control and sensory noise) are different, leading to different internal model uncertainty and ultimately different behaviors and strategies (Johnson et al, 2017a).…”

“…As shown in Markovic et al (2018b), when the supplemental information on the generated force was transmitted through a visual interface after the subjects trained controlling the prosthesis using incidental feedback, the force scaling improved only modestly and mainly at high force levels. It was demonstrated in a recent study (Risso et al, 2019) that an amputee subject with an implanted sensory feedback interface integrated supplementary somatosensory feedback and blurred visual information in a statistically optimal fashion when estimating the size of a hand-held object. If the supplementary feedback is characterized with a higher uncertainty compared to incidental sources, its impact on the control will likely be minimal if any.…”

Sensitivity to temporal parameters of intraneural tactile sensory feedback

“…Additionally, since recently it has been demonstrated that artificial intraneural stimulation was optimally integrated with visual feedback [29], the cross-modal effect of both temporal processing and multisensory integration [24] should be investigated.…”