Visual Influence on Postural Reactions to Sudden Antero-posterior Support Surface Movements

1991 ◽  
Vol 111 (4) ◽  
pp. 813-819 ◽  
Author(s):  
T. Ledin ◽  
L. M. Ödkvist
2010 ◽  
Vol 104 (5) ◽  
pp. 2704-2712 ◽  
Author(s):  
Lars B. Oude Nijhuis ◽  
John H. J. Allum ◽  
Josep Valls-Solé ◽  
Sebastiaan Overeem ◽  
Bastiaan R. Bloem

Unexpected support-surface movements delivered during stance elicit “first trial” postural reactions, which are larger and cause greater instability compared with habituated responses. The nature of this first trial reaction remains unknown. We hypothesized that first trial postural reactions consist of a generalized startle reaction, with a similar muscle synergy as the acoustic startle response, combined with an automatic postural reaction. Therefore we compared acoustic startle responses to first trial postural reactions. Eight healthy subjects stood on a support surface that unexpectedly rotated backwards 10 times, followed by 10 startling acoustic stimuli, or vice versa. Outcome measures included full body kinematics and surface EMG from muscles involved in startle reactions or postural control. Postural perturbations and startling acoustic stimuli both elicited a clear first trial reaction, as reflected by larger kinematic and EMG responses. The ensuing habituation rate to repeated identical stimuli was comparable for neck and trunk muscles in both conditions. Onset latencies in neck muscles occurred significantly later for first trial perturbations compared with startle responses, but earlier in trunk muscles. Our results show that platform tilting initially induces reactions larger than needed to maintain equilibrium. For neck and trunk muscles, these first trial postural reactions resembled acoustic startle reflexes. First trial postural reactions may be triggered by interaction of afferent volleys formed by somatosensory and vestibular inputs. Acoustic startle reactions may also be partially triggered by vestibular inputs. Similar muscle activation driven by vestibular inputs may be the common element of first trial postural responses and acoustic startle reactions.


2016 ◽  
Vol 47 ◽  
pp. 96-102 ◽  
Author(s):  
Taylor W. Cleworth ◽  
Romeo Chua ◽  
J. Timothy Inglis ◽  
Mark G. Carpenter

2005 ◽  
Vol 21 ◽  
pp. S43
Author(s):  
M.G. Carpenter ◽  
C.D. Tokuno ◽  
A. Thorstensson ◽  
A.G. Cresswell

2009 ◽  
Vol 29 (4) ◽  
pp. 603-611 ◽  
Author(s):  
Julie N. Côté ◽  
Isabelle Patenaude ◽  
Nancy St-Onge ◽  
Joyce Fung

2020 ◽  
Vol 74 ◽  
pp. 102715
Author(s):  
HaoYuan Hsiao ◽  
Robert A. Creath ◽  
Ozell Sanders ◽  
Mario Inacio ◽  
Brock A. Beamer ◽  
...  

2004 ◽  
Vol 92 (6) ◽  
pp. 3255-3265 ◽  
Author(s):  
M. G. Carpenter ◽  
J. S. Frank ◽  
A. L. Adkin ◽  
A. Paton ◽  
J.H.J. Allum

Previous studies have shown significant effects of increased postural anxiety in healthy young individuals when standing quietly or performing voluntary postural tasks. However, little is known about the influence of anxiety on reactive postural control. The present study examined how increased postural anxiety influenced postural reactions to unexpected surface rotations in multiple directions. Ten healthy young adults (mean age: 25.5 yr, range: 22–27 yr) were required to recover from unexpected rotations of the support surface (7.5° amplitude, 50°/s velocity) delivered in six different directions while standing in a low postural threat (surface height: 60 cm above ground) or high postural threat (surface height: 160 cm above ground) condition. Electromyographic data from 12 different postural leg, hip, and trunk muscles was collected simultaneously. Full body kinematic data were also used to determine total body center of mass (COM) and segment displacements. Four distinct changes were observed with increased postural anxiety: increased amplitude in balance-correcting responses (120–220 ms) in all leg, trunk, and arm muscles; decreased onset latency of deltoid responses; reduced magnitude of COM displacement; and reduced angular displacement of leg, pelvis, and trunk. These observations suggest that changes in dynamic postural responses with increased anxiety are mediated by alterations in neuro-muscular control mechanisms and thus may contribute significantly to the pathophysiology of balance deficits associated with aging or neurological disease.


Robotics ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 101
Author(s):  
Lara A. Thompson ◽  
Mehdi Badache ◽  
Joao Augusto Renno Brusamolin ◽  
Marzieh Savadkoohi ◽  
Jelani Guise ◽  
...  

For the rapidly growing aging demographic worldwide, robotic training methods could be impactful towards improving balance critical for everyday life. Here, we investigated the hypothesis that non-bodyweight supportive (nBWS) overground robotic balance training would lead to improvements in balance performance and balance confidence in older adults. Sixteen healthy older participants (69.7 ± 6.7 years old) were trained while donning a harness from a distinctive NaviGAITor robotic system. A control group of 11 healthy participants (68.7 ± 5.0 years old) underwent the same training but without the robotic system. Training included 6 weeks of standing and walking tasks while modifying: (1) sensory information (i.e., with and without vision (eyes-open/closed), with more and fewer support surface cues (hard or foam surfaces)) and (2) base-of-support (wide, tandem and single-leg standing exercises). Prior to and post-training, balance ability and balance confidence were assessed via the balance error scoring system (BESS) and the Activities specific Balance Confidence (ABC) scale, respectively. Encouragingly, results showed that balance ability improved (i.e., BESS errors significantly decreased), particularly in the nBWS group, across nearly all test conditions. This result serves as an indication that robotic training has an impact on improving balance for healthy aging individuals.


Nanomaterials ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 187
Author(s):  
Daria Chernysheva ◽  
Ludmila Pudova ◽  
Yuri Popov ◽  
Nina Smirnova ◽  
Olga Maslova ◽  
...  

A series of NiO/C nanocomposites with NiO concentrations ranging from 10 to 90 wt% was synthesized using a simple and efficient two-step method based on non-isothermal decomposition of Nickel(II) bis(acetylacetonate). X-ray diffraction (XRD) measurements of these NiO/C nanocomposites demonstrate the presence of β-NiO. NiO/C nanocomposites are composed of spherical particles distributed over the carbon support surface. The average diameter of nickel oxide spheres increases with the NiO content and are estimated as 36, 50 and 205 nm for nanocomposites with 10, 50 and 80 wt% NiO concentrations, respectively. In turn, each NiO sphere contains several nickel oxide nanoparticles, whose average sizes are 7–8 nm. According to the tests performed using a three-electrode cell, specific capacitance (SC) of NiO/C nanocomposites increases from 200 to 400 F/g as the NiO content achieves a maximum of 60 wt% concentration, after which the SC decreases. The study of the NiO/C composite showing the highest SC in three- and two-electrode cells reveals that its SC remains almost unchanged while increasing the current density, and the sample demonstrates excellent cycling stability properties. Finally, NiO/C (60% NiO) composites are shown to be promising materials for charging quartz clocks with a power rating of 1.5 V (30 min).


2013 ◽  
Vol 2013 ◽  
pp. 1-15 ◽  
Author(s):  
Karolina Szwarc-Rzepka ◽  
Filip Ciesielczyk ◽  
Teofil Jesionowski

Alkoxysilane-grafted silica/polyhedral oligomeric silsesquioxane with methacryl substituents (SiO2/silane/POSS) hybrid material was synthesized according to hydrolyzation and condensation reactions in the so-called “bifunctionalization process.” It is a new attractive system because of its physicochemical, especially thermal and structural, properties. This innovative method of preparation as well as specific physicochemical and useful properties determine the potential applications of such products in many industries. The structure and physicochemical parameters of obtained hybrid systems were characterized using infrared spectroscopy (FTIR),13C and29Si solid-state nuclear magnetic resonance (CP MAS NMR), and thermal analysis. The mechanism of bifunctionalization reaction was proposed. The chemical immobilization of silane coupling agent and Methacryl POSS onto silica support surface was noted during the study. Those changes caused a significant increase in the hydrophobic character of fillers obtained. Moreover, changes in thermal stability of SiO2/silane/POSS hybrid systems in comparison to pure POSS modifier were also observed.


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