Study of Electrical Neural Stimulation Effects Using Extraneural and Intraneural Electrodes

Sensory feedback restoration in upper-limb neuroprosthetics can significantly enhance amputees' quality of life. Neural interfaces allow the elicitation of sensory information through current stimuli. Stimulation studies can be useful to evaluate the electric potential distribution into the nerve in response to a current stimulus and therefore the activation of fibers. In this paper, hybrid FEM-Neuron computational models are used to study nerve fiber activation in different nerve models that resemble the human median nerve. To conduct a comprehensive study, the variability in fascicular topography and different configurations of active sites of two types of electrodes (intraneural and extraneural) has been considered. Furthermore, the simulation results (in terms of the percentage of fiber activation in nerve fascicles, their location in the nerve section models, and the order of their activation when the stimulus increases) are evaluated according to the sensation intensity perceived by a human amputee in an experimental trial. The obtained results let us infer the effect of using intraneural and extraneural electrodes on the number and position of activated fascicles when the minimum values of electric charges considered in the experimental trial are used, and the dependence of the order of fiber activation into the fascicles on the current stimulus.