Virtual Neuroprosthesis: Restoring a Sense of Touch to Amputees

Not Applicable

Completed

Brief Summary: The overall goal of this project is to develop a virtual neuroprosthesis in which a facsimile of a neural implant is externalized and housed in a well-controlled microfluidic chamber, thereby abating the intrinsic limitations of highly invasive studies with neural implants. Able-bodied and upper limb amputee subjects will be recruited to control a dexterous artificial hand and arm with electromyogram signals while electroencephalogram (EEG) signals are simultaneously measured. Robotic grip force measurements will be biomimetically converted into electrical pulses similar to those found in the peripheral nervous system to catalyze in vitro nerve regeneration after neurotrauma. The synergistic contributions of this multidisciplinary project will lead to a transformative understanding of the symbiotic interaction of neural plasticity within human-robotic systems. Currently, there is no systematic understanding of how tactile feedback signals can contribute to the neural regeneration of afferent neural pathways to restore somatosensation and improve motor function in amputees fitted with neuroprosthetic limbs. Tackling this problem will be a significant breakthrough for the important field of neuroprosthetics.

Detailed Description: Over one week, neurobehavioral processes will be examined in people controlling a robotic arm and hand to perform simple motor tasks (e.g. fragile object transportation), while a virtual peripheral nerve regeneration protocol provides users with biologically-realistic, idiosyncratic parameters for the restoration of haptic sensation (in double-blind fashion, the cellular neurophysiologists characterizing neural regeneration with microscopy are unaware of subjects' name and condition; and the human-subject experimenters are unaware of the haptic feedback parameter that will be used in the experiment each day, which is entered by the neurophysiologist in a black-box section of the software in the case of microscopic evaluation of nerve regeneration (early part of the project), or which is automatically input by the system in the case of real time impedimetric measurements (later part of the project)).

The main experimental factors are 'haptic feedback', with three modalities: full, partial (nerve-regeneration dependent) and null; and to challenge human control strategy and impose demand on haptic information, the 'transported object weight' (heavy, medium and lightweight).

Recording techniques: Subjects' electroencephalography (EEG), electromyography (EMG) and behavioral performance.

Recruitment & Eligibility

Inclusion Criteria

Exclusion Criteria

Arm && Interventions

Group	Intervention	Description
Nerve Growth During Prosthesis Control	Sensory Restoration During Prosthesis Control	Determine the optimum conditions that promote sensory restoration in limb-absent people, with an adaptive haptic feedback control law that mimics the experience of neural plasticity. The intervention Sensory Restoration During Prosthesis Control will be used.

Primary Outcome Measures

Name	Time	Method
Artificial Hand Grasp Performance Metrics	1 week	The percentage that grasped objects are successfully transported without slip or drop when controlled by amputees using an artificial hand.

Secondary Outcome Measures

Name	Time	Method
Dorsal Root Ganglia Neurite Regeneration	1 week	The length of neurite regeneration 1 week post-axotomy will be quantified. The dorsal root ganglia will be cultured in vitro in a multichannel microelectrode array. The neural culture will be electrically stimulated based on the touch sensations from the artificial hand that is used by amputees. The fingertip touch sensations will be biomimetically converted into pulses that resemble action potentials for the electrical stimulation. The length of neurite regeneration was quantified using NeuronJ to compare images at the beginning and endpoints of the study.