Strict actions of the human wrist flexors: A study with an electrical neuromuscular stimulation method

Narita, Aya; Sagae, Masaaki; Suzuki, Katsuhiko; Fujita, Takaaki; Sotokawa, Tasuku; Nakano, Haruki; Sato, Toshiaki; Fujii, Hiromi; Nito, Mitsuhiro; Hashizume, Wataru; Ogino, Toshihiko; Naito, Akira

doi:10.1016/j.jelekin.2015.04.004

Cited by 6 publications

(1 citation statement)

References 24 publications

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“…The surface electrodes in contact with the forehead were made of SUS316, a material commonly used for medical surface electrodes because of its nontoxicity and high biocompatibility [21][22][23][24]. The electrical resistivity of SUS316 was 0.74x10^-6 ohm-cm, the contact area between the electrodes and forehead was 5 mm × 3 mm, and the four corners were rounded.…”

Section: Electrodesmentioning

confidence: 99%

Enhancing Visual Perception for People with Blindness: A Feasibility Study of a 12-Channel Forehead ElectroTactile Stimulator with a Stereo Camera

Shin,

Lee,

Chang

et al. 2024

Preprint

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Background Although many alternative visual technologies for the visually impaired have been studied, no system has been developed that provides distance information on multiple objects in front of a person with blindness while in a walking environment via electrotactile stimulation. Therefore, we studied the feasibility of a 12-channel electrotactile stimulator (Forehead ElectroTactile Stimulator [FETS]) designed for those with visual impairment. It used a stereo camera to capture depth information and adjusted the voltage output for each channel. It also used a deep-learning algorithm to identify objects and converted this information into speech. Methods Medical-grade SUS316 surface electrodes were mounted on a flexible silicone pad to increase the contact area with the forehead. The stimulator delivered pulsed voltages up to ± 25 V, adjustable in 2.5-V increments. The pulsed voltage parameters were set to activate A-beta nerve fibers without activating pain-related A-delta and C nerve fibers. The stereo camera captured depth information from 1 to 3 m, focusing on the proximity to the user. YOLOv8 was used to detect objects from the input video in real-time and convert the results into speech via text-to-speech (TTS). Results The developed FETS could output voltages from 0 to 25 V in 100 steps via Bluetooth communication, and the maximum standard deviation of the actual output voltage from the set voltage was 0.71 V. The FETS output voltage intensity was adjustable in real time according to the distance to the object captured by the stereo camera. The FETS could recognize objects in front of the user upon request and provided voice guidance through TTS. Conclusion We conducted this feasibility study to enhance the vision of people with visual impairment by applying a stereo camera and electrotactile stimulation to their foreheads. Information about the distance to the object acquired through the stereo camera was implemented by adjusting the output voltage according to the distance from the electrotactile stimulator. The object was identified through an artificial-intelligence algorithm and delivered by voice. However, the threshold voltage and just noticeable difference values are not the same for each person; therefore, further research is needed.

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Section: Electrodesmentioning

confidence: 99%

Enhancing Visual Perception for People with Blindness: A Feasibility Study of a 12-Channel Forehead ElectroTactile Stimulator with a Stereo Camera

Shin,

Lee,

Chang

et al. 2024

Preprint

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Facilitation from flexor digitorum superficialis to extensor carpi radialis in humans

et al. 2016

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Effects of low-threshold afferents from the flexor digitorum superficialis (FDS) to the extensor carpi radialis (ECR) motoneurons were examined using a post-stimulus time-histogram (PSTH) and electromyogram-averaging (EMG-A) methods in eight healthy human subjects. In the PSTH study in five of the eight subjects, electrical conditioning stimuli (ES) to the median nerve branch innervating FDS with the intensity below the motor threshold induced excitatory effects (facilitation) in 39 out of 92 ECR motor units. In 11 ECR motor units, the central synaptic delay of the facilitation was -0.1 ± 0.3 ms longer than that of the homonymous facilitation of ECR. Mechanical conditioning stimuli (MS) to FDS with the intensity below the threshold of the tendon(T)-wave-induced facilitation in 51 out of 51 ECR motor units. With the EMG-A method, early and significant peaks were produced by ES and MS in all the eight subjects. The difference between latencies of the peaks by ES and MS was almost equivalent to that of the Hoffmann- and T-waves of FDS by ES and MS. The peak was diminished by tonic vibration stimuli to FDS. These findings suggest that a facilitation from FDS to ECR exists in humans and group Ia afferents mediate the facilitation through a monosynaptic path.

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Oligosynaptic inhibition mediated by group Ia afferents from flexor digitorum superficialis to wrist flexors in humans

et al. 2018

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Effects of low-threshold afferents from the flexor digitorum superficialis (FDS) to the flexor carpi radialis (FCR), flexor carpi ulnaris (FCU) and extensor carpi ulnaris (ECU) motoneurons were examined using a post-stimulus time-histogram (PSTH) and electromyogram-averaging (EMG-A) methods in seven healthy human subjects. Electrical conditioning stimulation to the median nerve branch innervating FDS with the intensity immediately below the motor threshold was delivered. In the PSTH study, the stimulation produced a trough (inhibition) in 19/44 (43%) of FCR and 17/41 (41%) of FCU motor units. Remaining motor units received no facilitatory and inhibitory effects. The central latency of the inhibition was 1.1 ± 0.6 ms (mean ± SD) and 0.6 ± 0.4 ms longer than that of the homonymous monosynaptic Ia facilitation of FCR and FCU, respectively. In the EMG-A study, the stimulation produced a trough (inhibition) in EMG-A of FCR and FCU in all the seven subjects. Amount of the inhibition was 14.5 ± 3.8% (FCR) and 17.9 ± 2.5% (FCU). Since the inhibition diminished after withdrawal of tonic vibration stimuli to the FDS muscle belly, group Ia afferents should be responsible for the inhibition. The stimulation did not produce facilitatory or inhibitory effect on ECU motoneurons in both the PSTH and EMG-A studies. These findings suggest that group Ia afferents from FDS inhibit excitability of motoneurons supplying FCR and FCU through an oligo (di- or tri-) synaptic path in the spinal cord. The reflex arcs would function to prevent wrist flexion during hand grasping movements.

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Strict actions of the human wrist flexors: A study with an electrical neuromuscular stimulation method

Cited by 6 publications

References 24 publications

Enhancing Visual Perception for People with Blindness: A Feasibility Study of a 12-Channel Forehead ElectroTactile Stimulator with a Stereo Camera

Enhancing Visual Perception for People with Blindness: A Feasibility Study of a 12-Channel Forehead ElectroTactile Stimulator with a Stereo Camera

Facilitation from flexor digitorum superficialis to extensor carpi radialis in humans

Oligosynaptic inhibition mediated by group Ia afferents from flexor digitorum superficialis to wrist flexors in humans

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