Perception caused by current amplitude variation in electro-tactile stimulation

Abstract

Prosthetic hand devices are used to overcome the difficulties accompanying loss of the tactile abilities. We target the recreation of tactile sensations using electric stimulation as part of a feedback system for prosthetic devices. The experiment here described employed electric current with fixed parameters and variable amplitude for the excitation of the nerve fibers attached to the Merkel Disks Receptors of the skin. The amplitude thresholds defining the current interval to work with were determined for 10 subjects. These values ranged between 1.00-3.50 mA and 6.00-15.00 mA, respectively, different among the subjects, which indicated the individual differences in perceptual functioning. The discrimination ability of the subjects, specifying the required amplitude variation between stimuli to be differentiated, was characterized using a linear regression model. The resulting discrimination ability value varied between 1.00-2.50 mA/sensation. A set of tactile descriptors related to the electrically-elicited sensations were quantified in accordance to the number of times they were reported. The result suggested that the elicited- sensations were comparable to the mechanicallygenerated sensations, being also easily describable and localizable. © 2011 Springer-Verlag Berlin Heidelberg.