Supplemental vibrotactile feedback of real-time limb position enhances precision of goal-directed reaching

Abstract

We examined vibrotactile stimulation as a form of supplemental limb state feedback to enhance planning and ongoing control of goal-directed movements. Subjects wore a two-dimensional vibrotactile display on their nondominant arm while performing horizontal planar reaching with the dominant arm. The vibrotactile display provided feedback of hand position such that small hand displacements were more easily discriminable using vibrotactile feedback than with intrinsic proprioceptive feedback. When subjects relied solely on proprioception to capture visuospatial targets, performance was degraded by proprioceptive drift and an expansion of task space. By contrast, reach accuracy was enhanced immediately when subjects were provided vibrotactile feedback and further improved over 2 days of training. Improvements reflected resolution of proprioceptive drift, which occurred only when vibrotactile feedback was active, demonstrating that benefits of vibrotactile feedback are due, in part to its integration into the ongoing control of movement. A partial resolution of task space expansion persisted even when vibrotactile feedback was inactive, demonstrating that training with vibrotactile feedback also induced changes in movement planning. However, the benefits of vibrotactile feedback come at a cognitive cost. All subjects adopted a stereotyped strategy wherein they attempted to capture targets by moving first along one axis of the vibrotactile display and then the other. For most subjects, this inefficient approach did not resolve over two bouts of training performed on separate days, suggesting that additional training is needed to integrate vibrotactile feedback into the planning and online control of goal-directed reaching in a way that promotes smooth and efficient movement. NEW & NOTEWORTHY A two-dimensional vibrotactile display provided state (not error) feedback to enhance control of a moving limb. Subjects learned to use state feedback to perform blind reaches with accuracy and precision exceeding that attained using intrinsic proprioception alone. Feedback utilization incurred substantial cognitive cost: subjects moved first along one axis of the vibrotactile display, then the other. This stereotyped control strategy must be overcome if vibrotactile limb state feedback is to promote naturalistic limb movements.

Vibration Propagation on the Skin of the Arm

“…We attached a multi-channel feedback interface to the less affected arm, with inter-stimulus distances greater than 8 cm. The interface provided hand position feedback of the more affected arm to the non-moving, less-affected arm [18,43,44]. While the system proved to be effective in improving the accuracy of simple, single-degree-of-freedom movements [45], future work is focused on determining efficacy on multi-degree-of-freedom movements.…”

Supplemental vibrotactile feedback of real-time limb position enhances precision of goal-directed reaching

“…These design choices enabled us to test two main hypotheses: (1) that neurologically-intact humans can learn to use vibrotactile limb state feedback to enhance the on-going control of a moving limb beyond the limits of intrinsic proprioception; and (2) that this training has aftereffects on subsequent movements performed without concurrent supplemental vibrotactile feedback (i.e., that training induces improved proprioceptive control; c.f., Cuppone et al, 2016). Preliminary aspects of this study have been presented in abstract form (Risi et al 2016(Risi et al , 2017.…”

Integrating Tactile Feedback Technologies Into Home-Based Telerehabilitation: Opportunities and Challenges in Light of COVID-19 Pandemic

“…Typically, the actuators used in wearable devices produce vibration at frequencies above 100 Hz, which activates the Pacinian corpuscles mechanoreceptors (Culbertson et al, 2018b ). The most common locations for applying the vibrotactile stimulation are the arm (Bark et al, 2008 ; Huisman et al, 2013 ; Krueger et al, 2017 ; Shah et al, 2018 ; Risi et al, 2019 ) and the torso (Van Erp et al, 2005 ; Lee et al, 2012 ; Ballardini et al, 2020 ). Other locations for stimulation include the hand (Jiang et al, 2009 ; Wan et al, 2016 ) and different locations on the lower limb (Chen B. et al, 2016 ; Shi et al, 2019 ).…”

“…The vibration intensity can be constant or may vary according to the event (Cobus et al, 2018 ). Continuous vibrotactile stimulation is used to convey various types of information to the users, including: (1) state feedback, encoding position and/or velocity of limbs (Ferris and Sarter, 2011 ; Krueger et al, 2017 ; Shah et al, 2018 ; Risi et al, 2019 ), (2) force feedback, encoding the amount of force exerted (Ahmaniemi, 2012 ), and (3) error feedback, encoding information regarding the goal of the task and the state of the end-effector (Wall et al, 2001 ; Cuppone et al, 2016 ; Krueger et al, 2017 ).…”

“…It has been demonstrated that state feedback regarding the force exerted improved the accuracy of force repetition (Ahmaniemi, 2012 ). Other studies used state and/or error feedback to guide upper limb reaching movements in the absence of visual information (Krueger et al, 2017 ; Shah et al, 2018 ; Risi et al, 2019 ) and to reach accuracy levels beyond the limits of natural proprioception (Risi et al, 2019 ). Results from a meta-analysis indicated that vibrotactile feedback was effective in reducing task completion times, but neither forces nor errors were significantly reduced (Nitsch and Färber, 2012 ).…”