Highly integrated bionic prostheses resolve the thermal asymmetry between residual amputated and contralateral limbs.

Residual limbs after amputation present colder temperatures than unaffected contralateral limbs. This temperature asymmetry has been attributed to autonomic and cognitive factors, such as changes in body representation. An ideal limb replacement should restore the body representation and resolve the temperature asymmetry, but conventional prostheses, commonly characterized as disembodied, fail to do so. Neuromusculoskeletal prostheses are a new concept of artificial limbs that directly interface with the user's nerves, muscles, and skeleton, and are operated in daily life by bidirectionally transferring control and somatosensory information. Here, we show that the temperature asymmetry commonly found in people with amputations is resolved when using a neuromusculoskeletal prosthesis but reappears when it is removed. A potential explanation for this phenomenon might be the increased embodiment reported by users of neuromusculoskeletal prostheses, which in turn would suggest unconscious perceptual mechanisms mediating the temperature asymmetry commonly found between intact and residual limbs after amputation.

Hand Temperature Is Not Consistent With Illusory Strength During the Rubber Hand Illusion.

The rubber hand illusion is known to invoke a sense of ownership of a rubber hand when a person watches the stroking of the rubber hand in synchrony with their own hidden hand. Quantification of the sense of ownership is traditionally performed with the rubber hand illusion questionnaire, but the search for reliable physiological measurements persists. Skin temperature has been previously suggested and debated as a biomarker for ownership. We investigated hand temperature as a measure of rubber hand illusory strength via thermal imaging of the hand during the rubber hand experiment. No relationship was found between reported illusory strength and skin temperature.Clinical Relevance- Our results indicate that skin temperature is not a suitable biomarker for rubber hand illusory strength.

Mathematical and Computational Models for Pain: A Systematic Review.

OBJECTIVE: There is no single prevailing theory of pain that explains its origin, qualities, and alleviation. Although many studies have investigated various molecular targets for pain management, few have attempted to examine the etiology or working mechanisms of pain through mathematical or computational model development. In this systematic review, we identified and classified mathematical and computational models for characterizing pain. METHODS: The databases queried were Science Direct and PubMed, yielding 560 articles published prior to January 1st, 2020. After screening for inclusion of mathematical or computational models of pain, 31 articles were deemed relevant. RESULTS: Most of the reviewed articles utilized classification algorithms to categorize pain and no-pain conditions. We found the literature heavily focused on the application of existing models or machine learning algorithms to identify the presence or absence of pain, rather than to explore features of pain that may be used for diagnostics and treatment. CONCLUSIONS: Although understudied, the development of mathematical models may augment the current understanding of pain by providing directions for testable hypotheses of its underlying mechanisms. Additional focus is needed on developing models that seek to understand the underlying mechanisms of pain, as this could potentially lead to major breakthroughs in its treatment.