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Abstract
Background and Objectives The restoration of touch to fingers and fingertips is critical to achieving dexterous neuroprosthetic control for individuals with sensorimotor dysfunction. However, localized fingertip sensations have not been evoked via intracortical microstimulation (ICMS).
Methods Using a novel intraoperative mapping approach, we implanted electrode arrays in the finger areas of left and right somatosensory cortex and delivered ICMS over a 2-year period in a human participant with spinal cord injury.
Results Stimulation evoked tactile sensations in 8 fingers, including fingertips, spanning both hands. Evoked percepts followed expected somatotopic arrangements. The subject was able to reliably identify up to 7 finger-specific sites spanning both hands in a finger discrimination task. The size of the evoked percepts was on average 33% larger than a finger pad, as assessed via manual markings of a hand image. The size of the evoked percepts increased modestly with increased stimulation intensity, growing 21% as pulse amplitude increased from 20 to 80 µA. Detection thresholds were estimated on a subset of electrodes, with estimates of 9.2 to 35 µA observed, roughly consistent with prior studies.
Discussion These results suggest that ICMS can enable the delivery of consistent and localized fingertip sensations during object manipulation by neuroprostheses for individuals with somatosensory deficits.
ClinicalTrials.gov Identifier NCT03161067.
Glossary
- BiCNS=
- Investigation on the Bidirectional Cortical Neuroprosthetic System;
- ECoG=
- electrocorticographic;
- FDA=
- Food and Drug Administration;
- ICMS=
- intracortical microstimulation;
- IQR=
- interquartile range;
- NHP=
- nonhuman primate;
- SCI=
- spinal cord injury;
- 3D-1U=
- 3 down–1 up;
- 2AFC=
- 2-alternative forced-choice
Footnotes
Go to Neurology.org/N for full disclosures. Funding information and disclosures deemed relevant by the authors, if any, are provided at the end of the article.
↵* These authors contributed equally to this work as first authors.
Editorial, page 261
- Received May 24, 2021.
- Accepted in final form November 19, 2021.
- © 2021 American Academy of Neurology
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