Supplemental vibrotactile feedback control of stabilization and reaching actions of the arm using limb state and position error encodings

Abstract

BackgroundDeficits of kinesthesia (limb position and movement sensation) commonly limit sensorimotor function and its recovery after neuromotor injury. Sensory substitution technologies providing synthetic kinesthetic feedback might re-establish or enhance closed-loop control of goal-directed behaviors in people with impaired kinesthesia.MethodsAs a first step toward this goal, we evaluated the ability of unimpaired people to use vibrotactile sensory substitution to enhance stabilization and reaching tasks. Through two experiments, we compared the objective and subjective utility of two forms of supplemental feedback – limb state information or hand position error – to eliminate hand position drift, which develops naturally during stabilization tasks after removing visual feedback.ResultsExperiment 1 optimized the encoding of limb state feedback; the best form included hand position and velocity information, but was weighted much more heavily toward position feedback. Upon comparing optimal limb state feedback vs. hand position error feedback in Experiment 2, we found both encoding schemes capable of enhancing stabilization and reach performance in the absence of vision. However, error encoding yielded superior outcomes - objective and subjective - due to the additional task-relevant information it contains.ConclusionsThe results of this study have established the immediate utility and relative merits of two forms of vibrotactile kinesthetic feedback in enhancing stabilization and reaching actions performed with the arm and hand in neurotypical people. These findings can guide future development of vibrotactile sensory substitution technologies for improving sensorimotor function after neuromotor injury in survivors who retain motor capacity, but lack proprioceptive integrity in their more affected arm.Electronic supplementary materialThe online version of this article (doi:10.1186/s12984-017-0248-8) contains supplementary material, which is available to authorized users.

Spatial and Temporal Influences on Discrimination of Vibrotactile Stimuli on The Arm

“…A second tactor was attached to the other indicated location. The two tactors were always placed at least 8cm apart, as results of pilot testing on the propagation of vibrations across the arm revealed that cross-coupling of vibration across stimulation sites was negligible with tactor separations greater than 6 cm [data not shown; see also (Krueger, Giannoni, Shah, Casadio, & Scheidt, 2017;Cipriani, D'Alonzo, & Carrozza, 2012)]. Participants completed 110 trials during each block, where they verbally indicated which of the two tested locations received the more "intense" stimulation.…”

“…Witteveen et al (2015) increased accuracy of grip force and hand aperture in prosthetic users by providing information about grip force and hand aperture with vibrotactile feedback. In our earlier work (Krueger, Giannoni, Shah, Casadio, & Scheidt, 2017), we investigated the use of vibrotactile sensory augmentation for upper extremity motor control. We applied vibrotactile feedback to the non-moving arm, conveying either limb-state or error information about the moving arm, leading to significant improvements in reaching and stabilization.…”

“…Various approaches to the development of sensory BMIs have included auditory, haptic, vibratory, and electro-stimulation [c.f., (Mussa-Ivaldi & Miller, 2003;Casadio, Ranganathan, & Mussa-Ivaldi, 2012)]. Vibrotactile feedback is an inexpensive and noninvasive method for displaying detailed sensory information to a user without taxing visual or auditory attention, while also improving environment exploration and motor control (Sienko, Balkwill, Oddsson, & Wall, 2008;Krueger, Giannoni, Shah, Casadio, & Scheidt, 2017;Tzorakoleftherakis, Murphey, & Scheidt, 2016;Cipriani, D'Alonzo, & Carrozza, 2012;An, Matsuoka, & Stepp, 2011).…”

“…Our investigations characterized the just noticeable differences of vibrotactile stimuli delivered to the arm and identified the effects of stimulus timing on vibrotactile perception. The results will advance the development of BMIs by enhancing the utility of information encoded within vibrotactile feedback, such as force sensation for upper extremity amputees (An, Matsuoka, & Stepp, 2011), kinesthetic information for survivors of stroke (Krueger, Giannoni, Shah, Casadio, & Scheidt, 2017), or the offloading of visual attention in spinal cord injury patients (Cincotti, et al, 2007).…”

Joint Speed Discrimination and Augmentation For Prosthesis Feedback

“…Sensory feedback remains a research priority for prosthesis users 6 . Several feedback methods have been proposed over the past decades, including vibrotactile [7][8][9][10][11] , electrotactile 8 , skin stretch 7 , audio [12][13][14] and visual 15 modalities 16,17 . More complex feedback modalities like peripheral nerve stimulation 18 and vibration-induced illusory kinesthesia 19 have also been introduced to great effect.…”