Year: 2020
Type: article
Abstract: CUBEROVICIn upper limb amputation, sensory feedback from the hand is lost, significantly reducing users' ability to interact with the environment, even with a prosthesis.Sensation location, one of four basic dimensions of somatosensation, provides valuable information about how the hand interacts with objects or the environment.Location is encoded by the receptive fields of individual axons and then cortically processed to create the perception of touch in the intact system.We hypothesized that artificial somatosensory locations are encoded, processed, and utilized similarly to intact somatosensory locations.We quantified the effects of various electrical and functional conditions on the location and functional use of evoked sensory percepts.Patient-specific computational and statistical models probed the underlying mechanisms driving experimental outputs.We found that peripheral nerves of the upper arm retain a somatotopic organization proximal to the elbow.Consequently, cuff electrodes, which recruit spatially grouped axon populations, encode focal percepts across targeted regions of the hand independent of placement along the peripheral nerve.However, functional use of the arm can induce some variability to the cuff-nerve interface.This changes the size of the active axon population and, correspondingly, the size of the perceived sensation location, as a prosthesis is actively used.xvi We also found that perception of artificial sensation is not solely dependent on the active axon population.Instead, like intact perception, top-down modulators influence tactile perception.Perceived sensory locations are more stable and more aligned with expected sensory locations when tested in a functional context.Further, this alignment becomes permanent with prolonged exposure to functionally-relevant artificial somatosensation over months of take-home usage.Such changes are dependent on the transduction of meaningful information through the percept; sensory locations associated with malfunctioning or non-informative prosthesis sensors actually become less aligned with their prosthesis sensors with usage.Finally, we found that the ability to use information from artificial somatosensory feedback depends on the colocalization of sensory feedback with the expected information.Specifically, participants can use and generalize the provided information more efficiently when the artificial sensory feedback is spatially aligned with the prosthesis.This work is the first to demonstrate that artificial sensory locations are encoded, processed, and utilized similarly to intact somatosensation.Functional sensory locations can be encoded using peripheral nerve stimulation throughout the upper limb and undergo integrative processing to create a conscious percept.Consequently, discrepancies between expected and artificial sensory feedback can be minimized through extant cortical processing.Finally, using artificial sensory locations in a way that takes advantage of pre-existing hand representations in the brain can increase information provided and ensuing functional benefit to users.
Author: Cuberovic, Ivana
Language: English
Subfield: Cellular and Molecular Neuroscience
Field: Neuroscience
Domain: Life Sciences
Open Access status: green
Award: G4915592993
OpenAlex ID: W7025212618