somatosensory stimulation
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2022 ◽  
Vol 11 (2) ◽  
pp. 425
Author(s):  
Yungon Lee ◽  
Sunghoon Shin

Patients with stroke suffer from impaired locomotion, exhibiting unstable walking with increased gait variability. Effects of rhythmic sensory stimulation on unstable gait of patients with chronic stroke are unclear. This study aims to determine the effects of rhythmic sensory stimulation on the gait of patients with chronic stroke. Twenty older adults with stroke and twenty age- and gender-matched healthy controls walked 60 m under four conditions: normal walking with no stimulation, walking with rhythmic auditory stimulation (RAS) through an earphone in the ear, walking with rhythmic somatosensory stimulation (RSS) through a haptic device on the wrist of each participant, and walking with rhythmic combined stimulation (RCS: RAS + RSS). Gait performance in the stroke group significantly improved during walking with RAS, RSS, and RCS compared to that during normal walking (p < 0.008). Gait variability significantly decreased under the RAS, RSS, and RCS conditions compared to that during normal walking (p < 0.008). Rhythmic sensory stimulation is effective in improving the gait of patients with chronic stroke, regardless of the type of rhythmic stimuli, compared to healthy controls. The effect was greater in patients with reduced mobility, assessed by the Rivermead Mobility Index (RMI).


Neurology ◽  
2021 ◽  
pp. 10.1212/WNL.0000000000013173
Author(s):  
Matthew Stephen Fifer ◽  
David P McMullen ◽  
Luke E Osborn ◽  
Tessy M Thomas ◽  
Breanne P Christie ◽  
...  

Background and Objectives:The restoration of touch to fingers and fingertips is critical to achieving dexterous neuroprosthetic control for individuals with sensorimotor dysfunction. However, localized fingertip sensations have not been evoked via intracortical microstimulation (ICMS).Methods:Using a novel intraoperative mapping approach, we implanted electrode arrays in the finger areas of left and right somatosensory cortex and delivered ICMS over a 2-year period in a human participant with spinal cord injury.Results:Stimulation evoked tactile sensations in 8 fingers, including fingertips, spanning both hands. Evoked percepts followed expected somatotopic arrangements. The subject was able to reliably identify up to 7 finger-specific sites spanning both hands in a finger discrimination task. The size of the evoked percepts was on average 33% larger than a fingerpad, as assessed via manual markings of a hand image. The size of the evoked percepts increased modestly with increased stimulation intensity, growing 21% as pulse amplitude increased from 20µA to 80µA. Detection thresholds were estimated on a subset of electrodes, with estimates of 9.2-35µA observed, roughly consistent with prior studies.Discussion:These results suggest that ICMS can enable the delivery of consistent and localized fingertip sensations during object manipulation by neuroprostheses for individuals with somatosensory deficits.Clinical Trial Information:This study is registered on ClinicalTrials.gov with identifier NCT03161067.


2021 ◽  
Author(s):  
Mirka Buist ◽  
Enzo Mastinu ◽  
Max Ortiz-Catalan

Abstract BACKGROUNDThis study describes the development and validation of a non-invasive wearable device to provide haptic feedback and train sensory discrimination. The ultimate aim of this device is to be used as part of a treatment for functional and/or pain rehabilitation due to sensorimotor impairment.METHODSThe development was guided by a structured design control process to ensure the verifiability and validity of the design outcomes. Two sub-systems were designed to systematically provide various types of somatosensory stimulation: 1) a tactile display for touch and vibration, and 2) a set of bands for sliding, pressure, and strain sensations. The device was designed with a versatile structure that allows for its application on different body parts. We designed an interactive computer program to command the device and enable training sessions. The validation of the device was performed with 11 able-bodied individuals whose upper arm tactile sensitivity was measured over 5 training sessions conducted daily. Tactile discrimination and perception threshold were measured using the standard 2-point discrimination and Semmes-Weinstein monofilament tests, respectively.RESULTSThe development and verification procedures ensured that the device successfully complied with the pre-established requirements, which were selected to enable the device clinical application. The results on tactile discrimination and sensitivity showed high subject-dependent variability but trended towards improvement (p=0.05). This trend was also confirmed by the scores achieved during the training sessions.CONCLUSIONSWe introduced a wearable device to deliver somatosensory stimulation and to train sensory discrimination. The design is versatile enough to allow for its application on different body parts. The device was found robust enough for clinical application, and it showed to increase tactile sensitivity on upper arms of able-bodied individuals. Further studies will be conducted to determine if our current findings transfer to individuals with sensorimotor impairment and if this approach is suitable for functional and/or pain rehabilitation after sensorimotor impairments.


2021 ◽  
Author(s):  
Nahian S Chowdhury ◽  
Nigel C Rogasch ◽  
Alan Chiang ◽  
Samantha K Millard ◽  
Patrick Skippen ◽  
...  

Background: Transcranial magnetic stimulation (TMS) evoked potentials (TEPs) can be used to index cortical excitability. However, it remains unclear to what extent TEPs reflect somatosensory and auditory-evoked potentials which arise from the scalp sensation and click of the TMS coil, as opposed to transcranial stimulation of cortical circuits. Objectives: The present study had two aims; a) to determine the extent to which sensory potentials contaminate TEPs using a spatially matched sham condition, and b) to determine whether sensory potentials reflect auditory or somatosensory potentials alone, or a combination of the two. Methods: Twenty healthy participants received active or sham stimulation, with the latter consisting of the click of a sham coil combined with scalp electrical stimulation. Earplugs/headphones were used to suppress the TMS click noise. Two additional control conditions i) electrical stimulation alone and ii) auditory stimulation alone were included in a subset of 13 participants. Results: Signals from active and sham stimulation were correlated in spatial and temporal domains, especially >70ms post-stimulation. Relative to auditory or electrical stimulation alone, combined (sham) stimulation resulted in a) larger evoked responses b) stronger correlations with active stimulation and c) a signal that could not be explained by the linear sum of electrical and auditory stimulation alone. Conclusions: Sensory potentials can confound data interpretations of TEPs at timepoints >70ms post-TMS, while earlier timepoints appear reflective of cortical excitability. Furthermore, contamination of TEPs cannot be explained by auditory or somatosensory potentials alone, but instead reflects a non-linear interaction between both sources. Future studies may benefit from controlling for sensory contamination using sham conditions that are spatially matched to active TMS, and which consist of combined auditory and somatosensory stimulation.


PLoS ONE ◽  
2021 ◽  
Vol 16 (11) ◽  
pp. e0259015
Author(s):  
Mattia Bruschetta ◽  
Ksander N. de Winkel ◽  
Enrico Mion ◽  
Paolo Pretto ◽  
Alessandro Beghi ◽  
...  

In dynamic driving simulators, the experience of operating a vehicle is reproduced by combining visual stimuli generated by graphical rendering with inertial stimuli generated by platform motion. Due to inherent limitations of the platform workspace, inertial stimulation is subject to shortcomings in the form of missing cues, false cues, and/or scaling errors, which negatively affect simulation fidelity. In the present study, we aim at quantifying the relative contribution of an active somatosensory stimulation to the perceived intensity of self-motion, relative to other sensory systems. Participants judged the intensity of longitudinal and lateral driving maneuvers in a dynamic driving simulator in passive driving conditions, with and without additional active somatosensory stimulation, as provided by an Active Seat (AS) and Active Belts (AB) integrated system (ASB). The results show that ASB enhances the perceived intensity of sustained decelerations, and increases the precision of acceleration perception overall. Our findings are consistent with models of perception, and indicate that active somatosensory stimulation can indeed be used to improve simulation fidelity.


2021 ◽  
Vol 11 (11) ◽  
pp. 1494
Author(s):  
Sho Kojima ◽  
Shota Miyaguchi ◽  
Hirotake Yokota ◽  
Kei Saito ◽  
Yasuto Inukai ◽  
...  

Motor evoked potentials (MEPs) evoked by transcranial magnetic stimulation (TMS) a few milliseconds after this cortical activity following electrical stimulation (ES) result in an inhibition comparable to that by TMS alone; this is called short-latency afferent inhibition (SAI). Cortical activity is observed after mechanical tactile stimulation (MS) and is affected by the number of stimuli by ES. We determined the effects of somatosensory stimulus methods and multiple conditioning stimuli on SAI in 19 participants. In experiment 1, the interstimulus intervals between the conditioning stimulation and TMS were 25, 27 and 29 ms for ES and 28, 30 and 32 ms for MS. In experiment 2, we used 1, 2, 3 and 4 conditioning stimulations of ES and MS. The interstimulus interval between the ES or MS and TMS was 27 or 30 ms, respectively. In experiment 1, MEPs were significantly decreased in both the ES and MS conditions. In experiment 2, MEPs after ES were significantly decreased in all conditions. Conversely, MEPs after MS were significantly decreased after one stimulus and increased after four stimulations, indicating the SAI according to the number of stimuli. Therefore, the somatosensory stimulus methods and multiple conditioning stimuli affected the SAI.


2021 ◽  
Author(s):  
Sanne Kikkert ◽  
Harshal Arun Sonar ◽  
Patrick Freund ◽  
Jamie Paik ◽  
Nicole Wenderoth

The exact somatotopy of the human facial representation in the primary somatosensory cortex (S1) remains debated. One reason that progress has been hampered is due the methodological challenge of how to apply automated vibrotactile stimuli to face areas in a manner that is: 1) reliable despite different curvature depending on the face location; and 2) MR-compatible and free of MR-interference artefacts when applied in the MR head-coil. Here we overcame this challenge by using soft pneumatic actuator (SPA) technology. SPAs are made of a soft silicon material and can be in- or deflated by means of airflow, have a small diameter, and are flexible in structure, enabling good skin contact even on curved body surfaces (as on the face). Here, we aimed to provide a methodological advance by providing automated tactile vibration stimulation inside the head-coil of the MRI. As a sanity check, we first mapped the well-characterised S1 finger layout using this novel device. We found that tactile stimulation of the fingers elicited characteristic somatotopic finger activations in S1, validating the use of our SPA-setup to map somatotopic representations. Ultimately, we used the device to automatically and systematically deliver somatosensory stimulation to different face locations. We found that the forehead representation was least distance from the representation of the hand. Within the face representation, we found that the lip representation is most distant from the forehead representation, with the chin represented in between. Together our results show that, by providing vibrotactile stimulation using the SPA-technology, we are able to reveal clear somatotopic representational patterns.


2021 ◽  
Vol 18 (5) ◽  
pp. 051003
Author(s):  
Jimmy Petit ◽  
José Rouillard ◽  
François Cabestaing

Abstract A brain–computer interface (BCI) aims to derive commands from the user’s brain activity in order to relay them to an external device. To do so, it can either detect a spontaneous change in the mental state, in the so-called ‘active’ BCIs, or a transient or sustained change in the brain response to an external stimulation, in ‘reactive’ BCIs. In the latter, external stimuli are perceived by the user through a sensory channel, usually sight or hearing. When the stimulation is sustained and periodical, the brain response reaches an oscillatory steady-state that can be detected rather easily. We focus our attention on electroencephalography-based BCIs (EEG-based BCI) in which a periodical signal, either mechanical or electrical, stimulates the user skin. This type of stimulus elicits a steady-state response of the somatosensory system that can be detected in the recorded EEG. The oscillatory and phase-locked voltage component characterising this response is called a steady-state somatosensory-evoked potential (SSSEP). It has been shown that the amplitude of the SSSEP is modulated by specific mental tasks, for instance when the user focuses their attention or not to the somatosensory stimulation, allowing the translation of this variation into a command. Actually, SSSEP-based BCIs may benefit from straightforward analysis techniques of EEG signals, like reactive BCIs, while allowing self-paced interaction, like active BCIs. In this paper, we present a survey of scientific literature related to EEG-based BCI exploiting SSSEP. Firstly, we endeavour to describe the main characteristics of SSSEPs and the calibration techniques that allow the tuning of stimulation in order to maximise their amplitude. Secondly, we present the signal processing and data classification algorithms implemented by authors in order to elaborate commands in their SSSEP-based BCIs, as well as the classification performance that they evaluated on user experiments.


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