11/24/2023 0 Comments Incontrol medical electrodeThe relevance of the upper-limb loss in the international scenario motivates the flourishing research in the field of upper-limb prosthetics. The hand loss causes severe impairment for the amputee and can significantly reduce quality of life. Restoration of afferent information in case of missing hand could thus be grounded on the substitution of the signal transduction system with artificial sensors on the prosthesis and the stimulation of peripheral nerves or higher order structures through neural interfaces (as detailed in Section Hand Sensorization). Transmission of sensory information from the hand to the brain relies on signal transduction at the skin surface and signal transmission to the brain cortex through first order and second order somatosensory neurons, via the dorsal-column medial lemniscal pathway. Pacinian corpuscles (PC), respond to high-frequency vibration they have large receptive fields and produce transient responses ( Saal and Bensmaia, 2014). Meissner corpuscles, associated with rapidly adapting (RA) fibers, respond to low-frequency skin vibrations and movements across the skin they have small receptive fields and produce transient responses at the onset and offset of stimulation. Ruffini endings, connected to slowly adapting type 2 (SA2) fibers, respond to skin stretch they have large receptive fields and produce sustained responses to static stimulation. Merkel discs, innervated by slowly adapting type 1 (SA1) afferents, underlie the perception of form and roughness they have small receptive fields and produce sustained responses to static stimulation. In physiological tactile sensation, there are four types of mechanoreceptors in glabrous skin that respond to mechanical pressure or distortion and send projections to the central nervous system via large-diameter nerve fibers. Individuals with intact upper-limb and motor pathways, deprived of somatosensory feedback, are characterized by slow and clumsy movements ( Sainburg et al., 1993) and experience the impossibility of attending to complex tasks, such as buttoning a jacket ( Sainburg et al., 1995). Proprioceptive and sensory feedback are of paramount importance in all the activities of daily living ( Johansson and Flanagan, 2009 Saal and Bensmaia, 2015). Intrinsic muscles, innervated by terminal branches of median and ulnar nerves, are responsible for fine motor control of the individual fingers, while extrinsic muscles, mostly innervated by median and radial nerves, produce gross flexion/extension movements of the whole hand and forceful grip. In the intact subject, hand movements are produced by more than thirty individual muscles located within the hand (intrinsic muscles) or forearm (extrinsic muscles). The complex mechanical structure, the composite sensory system, and the bidirectional communication between hand and brain make the human hand the most complex organ of the human body after the brain. The paper finally proposes a number of suggestions for designing the prosthetic system able to re-establish a bidirectional communication with the PNS and foster the prosthesis natural control. Special emphasis is then dedicated to the recent studies on the restoration of tactile perception in amputees through neural interfaces. Pros and cons of adopted technologies, signal processing techniques and motion control solutions are investigated. The study opens with an in-depth analysis of control solutions and sensorization features of research and commercially available prosthetic hands. This paper intends to provide a critical review of the literature on the technological issues on control and sensorization of hand prostheses interfacing with the Peripheral Nervous System (i.e., PNS), and their experimental validation on amputees. 3Institute of Neurology, Università Campus Bio-Medico di Roma, Roma, Italy.2INAIL Centro Protesi, Vigorso di Budrio, Italy.1Unit of Biomedical Robotics and Biomicrosystems, Department of Engineering, Università Campus Bio-Medico di Roma, Roma, Italy.Anna Lisa Ciancio 1 * Francesca Cordella 1 Roberto Barone 1 Rocco Antonio Romeo 1 Alberto Dellacasa Bellingegni 1 Rinaldo Sacchetti 2 Angelo Davalli 2 Giovanni Di Pino 3 Federico Ranieri 3 Vincenzo Di Lazzaro 3 Eugenio Guglielmelli 1 † Loredana Zollo 1 †
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