Restoring Finger-Specific Sensory Feedback for Transradial Amputees via Non-Invasive Evoked Tactile Sensation

Abstract

This study assessed the feasibility to restore finger-specific sensory feedback in transradial amputees with electrical stimulation of evoked tactile sensation (ETS). Methods: Here we investigated primary somatosensory cortical (SI) responses of ETS using Magnetoencephalography. Results: SI activations revealed a causal correlation with peripheral stimulation of projected finger regions on the stump skin. Peak latency was accountable to neural transmission from periphery to SI. Peak intensity of SI response was proportional to the strength of peripheral stimulation, manifesting a direct neural pathway from skin receptors to SI neurons. Active regions in SI at the amputated side were consistent to the finger/hand map of homunculus, forming a mirror imaging to that of the contralateral hand. With sensory feedback, amputees can recognize a pressure at prosthetic fingers as that at the homonymous lost fingers. Conclusions: Results confirmed that the direct neural pathway from periphery to SI allows effective communication of finger-specific sensory information to these amputees. INDEX TERMS Evoked tactile sensation (ETS), magnetoencephalography (MEG), prosthetic hand, sensory feedback, transcutaneous electrical nerve stimulation (TENS). IMPACT STATEMENT This study substantiated the neural basis and feasibility that electrically evoked tactile sensation can afford a non-invasive neural interface capable of restoring finger-specific sensory ability to transradial amputees.

Next-Generation Prosthetic Hand: from Biomimetic to Biorealistic

“… Noninvasive tactile sensory feedback: we have demonstrated the feasibility to utilize an electrically evoked tactile sensation (ETS) as a natural way to furnish sensory information to amputee's brain. This sensory feedback technique is noninvasive, has long-term stability, and can supply finger-specific, multiple modalities of natural sensory information to amputees [ 5 , 20 ]. This technology is currently undergoing evaluation of functional benefits in amputee subjects.…”

“…Past research has accumulated a large body of knowledge on human sensorimotor system [ 9 , 23 – 26 ]. It is now technologically mature to translate this body of knowledge to design biorealistic prosthetic hands that restore neuromuscular mechanics [ 6 ], spinal reflexes [ 13 ], and tactile feedback [ 3 – 5 , 7 ]. This may result in not only superior performance but also a new generation of prosthetic hands.…”

Effects of electrical stimulation on skin surface

“…16 a. Besides, Hao et al [ 111 ] show that electrical stimulation can also induce tactile sensation, thereby providing sensory feedback treatment for amputees. Most of the above studies are unilateral control, and the current interactive EMS research has gradually attracted attention.…”

Modulation Ranges of Different Sensations for Coding Electrically Evoked Tactile Sensory Feedback

“…The interface, the implanted location, and current parameters used in invasive techniques could affect the perceptual qualities [9], [10], [15] and multiple sensory modalities [8], [16]- [18]. While studies of peripheral nerve electrical stimulation show the sophisticated sensory function [17], [19], [20] with a relatively long time [11], [12], [21], non-invasive sensory feedback studies are still relatively limited in the use of sensation qualities [22], [23].…”