Is an artificial limb embodied as a hand? Brain decoding in prosthetic limb users.

Roni O Maimon-Mor,Tamar R Makin,Karunesh Ganguly

doi:10.1371/journal.pbio.3000729

Roni O Maimon-Mor, Tamar R Makin + Show 1 more

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https://doi.org/10.1371/journal.pbio.3000729

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Abstract

The potential ability of the human brain to represent an artificial limb as a body part (embodiment) has been inspiring engineers, clinicians, and scientists as a means to optimise human-machine interfaces. Using functional MRI (fMRI), we studied whether neural embodiment actually occurs in prosthesis users' occipitotemporal cortex (OTC). Compared with controls, different prostheses types were visually represented more similarly to each other, relative to hands and tools, indicating the emergence of a dissociated prosthesis categorisation. Greater daily life prosthesis usage correlated positively with greater prosthesis categorisation. Moreover, when comparing prosthesis users' representation of their own prosthesis to controls' representation of a similar looking prosthesis, prosthesis users represented their own prosthesis more dissimilarly to hands, challenging current views of visual prosthesis embodiment. Our results reveal a use-dependent neural correlate for wearable technology adoption, demonstrating adaptive use-related plasticity within the OTC. Because these neural correlates were independent of the prostheses' appearance and control, our findings offer new opportunities for prosthesis design by lifting restrictions imposed by the embodiment theory for artificial limbs.

Highlights

IntroductionThe development of wearable technology for substitution (e.g., prosthetic limbs [1], exoskeletons [2]) and augmentation (e.g., supernumerary fingers and arms [3]) is rapidly advancing
The development of wearable technology for substitution and augmentation is rapidly advancing.Clinical research on prosthetic limbs, the most established form of wearable motor technology to date, teaches us that technological development is necessary but not sufficient for successful device adoption and usage
We pitted the embodiment theory against another prominent theory—the categorisation theory—which is well established in visual neuroscience [43] but to our knowledge has not been explored for wearable devices

Summary

Introduction

The development of wearable technology for substitution (e.g., prosthetic limbs [1], exoskeletons [2]) and augmentation (e.g., supernumerary fingers and arms [3]) is rapidly advancing. Clinical research on prosthetic limbs, the most established form of wearable motor technology to date, teaches us that technological development is necessary but not sufficient for successful device adoption and usage. Only 45% of all arm amputees choose to use their prosthesis regularly [4]. The causes for prosthesis rejection are multiplex and include awkward control over the device, lack of tactile feedback, and complex training requirements [4,5,6].

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