Learning of Artificial Sensation Through Long-Term Home Use of a Sensory-Enabled Prosthesis.

Upper limb prostheses are specialized tools, and skilled operation is learned by amputees over time. Recently, neural prostheses using implanted peripheral nerve interfaces have enabled advances in artificial somatosensory feedback that can improve prosthesis outcomes. However, the effect of sensory learning on artificial somatosensation has not been studied, despite its known influence on intact somatosensation and analogous neuroprostheses. Sensory learning involves changes in the perception and interpretation of sensory feedback and may further influence functional and psychosocial outcomes. In this mixed methods case study, we examined how passive learning over 115 days of home use of a neural-connected, sensory-enabled prosthetic hand influenced perception of artificial sensory feedback in a participant with transradial amputation. We examined perceptual changes both within individual days of use and across the duration of the study. At both time scales, the reported percept locations became significantly more aligned with prosthesis sensor locations, and the phantom limb became significantly more extended toward the prosthesis position. Similarly, the participant's ratings of intensity, naturalness, and contact touch significantly increased, while his ratings of vibration and movement significantly decreased across-days for tactile channels. These sensory changes likely resulted from engagement of cortical plasticity mechanisms as the participant learned to use the artificial sensory feedback. We also assessed psychosocial and functional outcomes through surveys and interviews, and found that self-efficacy, perceived function, prosthesis embodiment, social touch, body image, and prosthesis efficiency improved significantly. These outcomes typically improved within the first month of home use, demonstrating rapid benefits of artificial sensation. Participant interviews indicated that the naturalness of the experience and engagement with the prosthesis increased throughout the study, suggesting that artificial somatosensation may decrease prosthesis abandonment. Our data showed that prosthesis embodiment was intricately related to naturalness and phantom limb perception, and that learning the artificial sensation may have modified the body schema. As another indicator of successfully learning to use artificial sensation, the participant reported the emergence of stereognosis later in the study. This study provides the first evidence that artificial somatosensation can undergo similar learning processes as intact sensation and highlights the importance of sensory restoration in prostheses.

The benefits of sensation on the experience of a hand: A qualitative case series.

BACKGROUND: The experience of upper limb loss involves loss of both functional capabilities and the sensory connection of a hand. Research studies to restore sensation to persons with upper limb loss with neural interfaces typically measure outcomes through standardized functional tests or quantitative surveys. However, these types of metrics cannot fully capture the personal experience of living with limb loss or the impact of sensory restoration on this experience. Qualitative studies can demonstrate the viewpoints and priorities of specific persons or groups and reveal the underlying conceptual structure of various aspects of their experiences. METHODS AND FINDINGS: Following a home use trial of a neural-connected, sensory-enabled prosthesis, two persons with upper limb loss were interviewed about their experiences using the sensory restoration system in unsupervised, unconstrained settings. We used grounded theory methodology to examine their experiences, perspectives, and opinions about the sensory restoration system. We then developed a model to describe the impact of sensation on the experience of a hand for persons with upper limb loss. CONCLUSIONS: The experience of sensation was complex and included concepts such as the naturalness of the experience, sensation modality, and the usefulness of the sensory information. Sensation was critical for outcome acceptance, and contributed to prosthesis embodiment, confidence, reduced focus and attention for using the prosthesis, and social interactions. Embodiment, confidence, and social interactions were also key determinants of outcome acceptance. This model provides a unified framework to study and understand the impact of sensation on the experience of limb loss and to understand outcome acceptance following upper limb loss more broadly.

Feminine identity and functional benefits are key factors in women's decision making about upper limb prostheses: a case series.

PURPOSE: Although the DEKA Arm promises new abilities, it is unclear if women with upper limb amputation are willing to avail themselves of this new technology. The study purpose was to understand key factors and tradeoffs that shape women's attitudes towards the DEKA Arm. METHODS: This case series includes three women with transradial amputation. Structured surveys and semi-guided interviews were administered after completion of in-laboratory training and a home trial of the DEKA Arm. A constant comparative method with a grounded theory approach was used to generate a model describing women's decision-making related to the DEKA Arm. Quantitative data on prosthetic satisfaction was used to triangulate findings. RESULTS: Factors that enhanced desirability of the DEKA Arm were improved functionality, increased abilities and the availability of someone to service the prosthesis. Factors that detracted from desirability of the device were its appearance, conspicuousness, lifestyle incompatibility, weight, need for service and difficulty of use. Each woman weighted these factors within the larger context of the capabilities of and satisfaction with her personal prostheses, her self-concept and lifestyle needs. Situational demands, particularly the desire to appear feminine and professional or need to perform certain activities, also altered the valuation of these priorities. CONCLUSION: Findings strongly suggest that advanced upper limb prosthetic technologies, like the DEKA Arm, will be better accepted by women if appropriately gendered in appearance and designed with women's priorities in mind. Implications for Rehabilitation Women should be able to derive the functional benefits of advances in upper limb technology without needing to compromise their feminine identity and lifestyle preferences. Advanced upper limb prosthetic technologies will be better accepted by women if they are appropriately gendered.