Intraneural stimulation elicits discrimination of textural features by artificial fingertip in intact and amputee humans

Abstract

Restoration of touch after hand amputation is a desirable feature of ideal prostheses. Here, we show that texture discrimination can be artificially provided in human subjects by implementing a neuromorphic real-time mechano-neuro-transduction (MNT), which emulates to some extent the firing dynamics of SA1 cutaneous afferents. The MNT process was used to modulate the temporal pattern of electrical spikes delivered to the human median nerve via percutaneous microstimulation in four intact subjects and via implanted intrafascicular stimulation in one transradial amputee. Both approaches allowed the subjects to reliably discriminate spatial coarseness of surfaces as confirmed also by a hybrid neural model of the median nerve. Moreover, MNT-evoked EEG activity showed physiologically plausible responses that were superimposable in time and topography to the ones elicited by a natural mechanical tactile stimulation. These findings can open up novel opportunities for sensory restoration in the next generation of neuro-prosthetic hands.DOI: http://dx.doi.org/10.7554/eLife.09148.001

Pursuing prosthetic electronic skin

“…Intracortical electrode 101,102 Epidural electrode 97,104 Optical fibre [113][114][115] Micro-light-emitting diode 118,120 Magnetic generator for transcranial magnetic stimulation 13,100 Interface with peripheral nervous system Surface electrode 105 Extra-fascicular electrode 106,107 Intra-fascicular electrode 108,109 Surface light pulse 116 Optical nerve cuff 117 Although the number of sensory signals that can be injected into the nervous system is currently limited, even a small number of sensors can substantially improve the utility of prosthetic devices 90,110 . To recover the ability to sense more complex stimuli such as surface textures and object shape, a large number of receptors is necessary.…”

“…6d inset (i)). Recently, the integration of an artificial fingertip tactile sensor with transverse intra-fascicular multichannel electrodes implanted in a patient has been reported, aiming at targeting fewer neurons inside peripheral nerve fascicles 109 . Sensor outputs were converted into biomimetic signals by an external set-up to reflect the different tactile stimuli.…”

Bionic Intrafascicular Interfaces for Recording and Stimulating Peripheral Nerve Fibers

“…This intrafascicular placement of the neural interface can be accomplished by using punctate penetrating arrays such as the Utah Slanted Electrode Array (USEA) [31–37], the transverse intrafascicular multichannel electrode array (TIME) [34,38], individual longitudinal intrafascicular electrodes (LIFEs) [32] or thin-film LIFEs [33,39]. Chronically implanted intrafascicular electrodes can elicit discrete activation of nerve fibers on electrical stimulation, as illustrated by reproducible and localized finger sensations or object discrimination capabilities in amputees [35,37–40].…”

“…Chronically implanted intrafascicular electrodes can elicit discrete activation of nerve fibers on electrical stimulation, as illustrated by reproducible and localized finger sensations or object discrimination capabilities in amputees [35,37–40]. …”

From Extension to Intrusion: A Medial Paradigm Shift?

“…The École Polytechnique Fédérale of Lausanne, as well as several universities in Italy, currently work on the differentiated texture perception by means of artificial fingertips. (Oddo 2016) A bionic hand, developed in Vienna and Göttingen, is not only able to transmit perceptual signals but also to execute commands, (Aszmann 2015) i.e. this method involves both afferent and efferent nerves.…”