Intracortical Somatosensory Stimulation to Elicit Fingertip Sensations in an Individual With Spinal Cord Injury

Neurology, 2022 · DOI: 10.1212/WNL.0000000000013173 · Published: February 15, 2022

Simple Explanation

This study explores the possibility of restoring the sense of touch to individuals with spinal cord injuries (SCI) using intracortical microstimulation (ICMS). The focus is on eliciting localized fingertip sensations, which are crucial for dexterous object manipulation. Microelectrode arrays were implanted in the somatosensory cortex of a participant with SCI, and ICMS was delivered over a 2-year period. The participant reported tactile sensations in multiple fingers, including the fingertips, across both hands. The study's findings suggest that ICMS can provide consistent and localized fingertip sensations, which could be integrated into neuroprostheses to improve object manipulation for individuals with somatosensory deficits.

Study Duration

2 years

Participants

1 participant with spinal cord injury

Evidence Level

Not specified

Key Findings

1
ICMS evoked tactile sensations in 8 fingers, including fingertips, spanning both hands, following expected somatotopic arrangements.
2
The subject was able to reliably identify up to 7 finger-specific sites spanning both hands in a finger discrimination task, with a mean accuracy of 99.0%.
3
The size of the evoked percepts was on average 33% larger than a finger pad, and increased modestly (21%) with increased stimulation intensity from 20 to 80 μA.

Research Summary

This study investigated the use of intracortical microstimulation (ICMS) to restore fingertip sensations in an individual with spinal cord injury (SCI). Microelectrode arrays were implanted in the somatosensory cortex, and stimulation was delivered over a 2-year period. The results demonstrated that ICMS could elicit tactile sensations in multiple fingers, including fingertips, across both hands. The subject could reliably identify finger-specific stimulation sites, and the evoked percepts were relatively focal. These findings suggest that ICMS has the potential to provide functional tactile feedback during object manipulation with prosthetic hands, improving the outcomes of ICMS-based artificial touch.

Practical Implications

Neuroprosthetic Development

The ability to elicit localized fingertip sensations via ICMS represents a significant advancement in the development of dexterous neuroprostheses. This can lead to improved object manipulation and a greater sense of independence for individuals with sensorimotor dysfunction.

Somatosensory Feedback

Restoring somatosensory feedback is crucial for enhancing the functionality and usability of prosthetic devices. ICMS-based artificial touch can provide real-time sensory information, allowing users to interact with their environment more effectively.

Clinical Applications

This research has the potential to translate into clinical applications for individuals with spinal cord injury and other conditions that result in the loss of touch. By providing a reliable and interpretable tactile feedback system, ICMS can improve the quality of life for these patients.

Study Limitations

1
The study was conducted with only 1 participant, which limits the generalizability of the findings.
2
The participant had a significant degree of retained sensation, which may have affected the cortical touch representations accessible via ICMS.
3
More work is needed to understand the degree of individual variability in the location of fingertip representations relative to the central sulcus.

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