Neural interfaces for somatosensory feedback

Abstract

Purpose of review-When an individual loses a limb, he/she loses touch with the world and with the people around him/her. Somatosensation is critical to the feeling of connection and control of one's own body. Decades of attempts to replace lost somatosensation by sensory substitutions have been ineffective outside of the laboratory. This review discusses important recent results demonstrating chronic somatosensory restoration through direct peripheral nerve stimulation.Recent findings-Stimulation of peripheral nerves results in somatosensory perception on the phantom limb. Sensations are localized to several independent and functionally relevant locations, such as the fingertips, thenar eminence, ulnar border and dorsal surface. Patterns in stimulation intensity change the perception experience by the user, opening new dimensions on neuromodulation.Summary-Neural interfaces with sophisticated stimulation paradigms create a user's perception of his/her hand to touch and manipulate objects. The pattern of intensity and frequency of stimulation is critical to the quality and intensity of perceived sensation. Restoring feeling has allowed the individuals to, 'feel [my] hand for the first time since the accident,' and 'feel [my] wife touch my hand'. Individuals using a prosthetic hand with sensation can pull cherries and grapes from the stem, open water bottles and move objects without destroying these objects -all while audio and visually deprived. After regaining sensation, phantom pain is eliminated in individuals that had frequent, sometimes debilitating, pain following limb loss. With over 5 subject-years of experience, this work is leading the evolution of a new era in prostheses. Somatosensory prosthetics as a standard procedure to augment and restore somatosensation are now within our reach.

Evoked haptic sensations in the hand via non-invasive proximal nerve stimulation

“…Upper limb amputation results in a loss of both motor and sensory function [1]. While recent technological advancements have resulted in substantial improvements in the mechanics and control of prosthetic devices, incorporating sensory feedback into these systems remains a largely unmet need [2]. A lack of sensory feedback to the users can drastically impact the usability of a prosthetic limb or hand.…”

Imaging fast neural traffic at fascicular level with electrical impedance tomography: proof of principle in rat sciatic nerve

“…These two techniques permit identification of anatomical organisation of fascicles but not their functional activity. This has been extensively studied using microelectrodes or, more recently, multielectrode arrays which are linear or 2D [7][8][9][10]. However, these only provide a limited subset of spiking activity from the several thousand axons present in most peripheral nerves, according to the chance apposition of the recording contacts.…”

On the Reliability of Chronically Implanted Thin-Film Electrodes in Human Arm Nerves for Neuroprosthetic Applications

“…Therefore, chronic stability of implanted PNIs is the ultimate prerequisite. By now, a limited amount of PNIs proved stability over a long period [3,19] like years.…”

“…Several research groups developed technological solutions to provide sensory feedback for bidirectional prosthetic limb control [1][2][3][4][5] to reduce rejection of prosthesis use [6,7], improve user's quality of life and increase dexterity [1,2,[8][9][10][11][12] as well as embodiment with a positive impact on that distressing condition named phantom limb pain (PLP) [11,[13][14][15][16]. In order to achieve optimal performance, peripheral nerve interfaces (PNIs) need to exhibit high spatial resolution, must show a limited foreign body reaction and must not exceed the electrochemical safe limits of stimulation [17].…”