The first objective of this study was to compare the cross-sectional areas of muscles and muscle force before and after 6 months of therapeutic electrical stimulation (TES) by using computed tomography (CT), Cybex II, a strain-gauge, and manual muscle test (MMT) in 5 complete paraplegics. The stimulation parameters were a frequency of 20 Hz, a pulse width of 0.2 ms, and an output voltage of -15V. The cross-sectional areas of muscle, the CT numbers, and both the muscle torque and the muscle force increased after TES, but the initial muscle force need to have been greater than a poor-minus level on MMT in order to achieve practical benefits from TES. Therefore TES should be started as early as possible after the onset of paraplegia in order to maintain and improve muscle quality. The second objective of this study was to re-chart the electrical stimulation used for reconstructing the standing-up motion in paraplegics. Twelve healthy subjects were monitored during two different kinds of standing-up motion: 1) standing-up while the arms remained crossed in front of the chest, and 2) hands-assisted standing-up using parallel bars. The electromyogram, joint angle, and the vertical component of the floor reaction force were synchronized with time, and investigated. The main muscles for standing-up are the quadriceps, the tibialis anterior, and the paraspinal muscles. Comparing 1) and 2), the hands-assisted standing-up was performed with less muscle activity except for the rectus femoris and the iliopsoas muscle, and with less maximum vertical floor reaction force. A T6 paraplegic patient could stand-up smoothly from a wheel-chair using the parallel bars after electrical stimulation based on data from the hands-assisted standing-up study on healthy subjects. In comparison with healthy subjects, the knee joints initially flexed before extending, and the ankle joints were more dorsiflexed in the paraplegic patient. The maximum vertical floor reaction force was also less.
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Hear Res
January 2025
Department of Neuroscience, University of Wisconsin-Madison, WI 53706, USA.
We developed an isolated auditory papilla of the crested gecko to record from the hair cells and explore the origins of frequency tuning. Low-frequency cells displayed electrical tuning, dependent on Ca-activated K channels; high-frequency cells, overlain with sallets, showed a variation in hair bundle stiffness which when combined with sallet mass could provide a mechanical resonance of 1 to 6 kHz. Sinusoidal electrical currents injected extracellularly evoked hair bundle oscillations at twice the stimulation frequency, consistent with fast electromechanical responses from hair bundles of two opposing orientations, as occur in the sallets.
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January 2025
Department of Electrical Engineering and ITEMS, University of Southern California, Los Angeles, California, USA.
As the clinical applicability of peripheral nerve stimulation (PNS) expands, the need for PNS-specific safety criteria becomes pressing. This study addresses this need, utilizing a novel machine learning and computational bio-electromagnetics modeling platform to establish a safety criterion that captures the effects of fields and currents induced on axons. Our approach is comprised of three steps: experimentation, model creation, and predictive simulation.
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February 2025
Discipline of Mechanical, Manufacturing and Biomedical Engineering, School of Engineering, Trinity College Dublin, Dublin 2, Ireland.
Peripheral nerve repair (PNR) is a major healthcare challenge due to the limited regenerative capacity of the nervous system, often leading to severe functional impairments. While nerve autografts are the gold standard, their implications are constrained by issues such as donor site morbidity and limited availability, necessitating innovative alternatives like nerve guidance conduits (NGCs). However, the inherently slow nerve growth rate (∼1 mm/day) and prolonged neuroinflammation, delay recovery even with the use of passive (no-conductive) NGCs, resulting in muscle atrophy and loss of locomotor function.
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December 2024
University of Illinois Urbana-Champaign, Urbana, IL, USA; Carle Foundation Hospital, Urbana, IL, USA; Department of Physical Therapy and Human Movement Sciences, Northwestern University, Chicago, IL 60611, USA.
Sensory feedback is crucial for motor control as it establishes the internal representation of motion. This study investigates changes in sensory feedback in hemiparetic stroke by analyzing the laterality index (LI) of somatosensory evoked potentials (SEPs) during movements of the paretic arm, focusing on a shift from the lesioned to the contralesional hemisphere. Three chronic stroke participants performed isometric lifts of their paretic arms at two different levels of their maximum voluntary contraction while receiving tactile finger stimulation.
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