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Postural reflexes

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https://www.readbyqxmd.com/read/28818139/bed-rest-and-intermittent-centrifugation-effects-on-human-balance-and-neuromotor-reflexes
#1
William H Paloski, Millard F Reschke, Alan H Feiveson
INTRODUCTION: The effects of repeated centrifugation in association with head-down tilt (HDT) bed rest (BR) on the mediation of basic reflexes associated with the major postural muscles was investigated as a potential countermeasure for maintaining balance control and neuromotor reflex function. METHODS: There were 15 male volunteers who were exposed to 21 d of 6° HDT-BR. Eight were treated with daily 1-h artificial gravity (AG) exposures aboard a short radius centrifuge that provided 1-g footward loading at heart level...
September 1, 2017: Aerospace Medicine and Human Performance
https://www.readbyqxmd.com/read/28798718/vestibular-modulation-of-sympathetic-nerve-activity-to-muscle-and-skin-in-humans
#2
REVIEW
Elie Hammam, Vaughan G Macefield
We review the existence of vestibulosympathetic reflexes in humans. While several methods to activate the human vestibular apparatus have been used, galvanic vestibular stimulation (GVS) is a means of selectively modulating vestibular afferent activity via electrodes over the mastoid processes, causing robust vestibular illusions of side-to-side movement. Sinusoidal GVS (sGVS) causes partial entrainment of sympathetic outflow to muscle and skin. Modulation of muscle sympathetic nerve activity (MSNA) from vestibular inputs competes with baroreceptor inputs, with stronger temporal coupling to the vestibular stimulus being observed at frequencies remote from the cardiac frequency; "super entrainment" was observed in some individuals...
2017: Frontiers in Neurology
https://www.readbyqxmd.com/read/28764704/objective-impairments-of-gait-and-balance-in-adults-living-with-hiv-1-infection-a-systematic-review-and-meta-analysis-of-observational-studies
#3
Karina Berner, Linzette Morris, Jochen Baumeister, Quinette Louw
BACKGROUND: Gait and balance deficits are reported in adults with HIV infection and are associated with reduced quality of life. Current research suggests an increased fall-incidence in this population, with fall rates among middle-aged adults with HIV approximating that in seronegative elderly populations. Gait and postural balance rely on a complex interaction of the motor system, sensory control, and cognitive function. However, due to disease progression and complications related to ongoing inflammation, these systems may be compromised in people with HIV...
August 1, 2017: BMC Musculoskeletal Disorders
https://www.readbyqxmd.com/read/28746244/the-effect-of-unicycle-riding-course-on-trunk-strength-and-trunk-stability-functions-in-children
#4
Andrej Kocjan, Nejc Sarabon
PURPOSE: The aim of the study was to assess the effect of unicycling on trunk strength and timing of automatic stability actions of the selected trunk muscles (multifidus, obliquus externus, erector spine). METHODS: Twenty healthy 12-year-old children (12 boys, 8 girls; age 12.1 ± 0.2 yrs; body height 1.57 ± 0.05 m; body mass 52.8 ± 10.6 kg) were assigned to experimental and control group. Experimental group performed a supervised 12-session course of unicycling...
July 24, 2017: Journal of Strength and Conditioning Research
https://www.readbyqxmd.com/read/28743726/why-new-spinal-cord-plasticity-does-not-disrupt-old-motor-behaviors
#5
Yi Chen, Lu Chen, Yu Wang, Xiang Yang Chen, Jonathan R Wolpaw
When new motor learning changes the spinal cord, old behaviors are not impaired; their key features are preserved by additional, compensatory, plasticity. To explore the mechanisms responsible for this compensatory plasticity, we transected the spinal dorsal ascending tract (DA) before or after female rats acquired a new behavior -- operantly conditioned increase or decrease in the right soleus H-reflex - and examined an old behavior - locomotion. Neither DA transection nor H-reflex conditioning alone impaired locomotion...
July 25, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28740669/impact-of-thoracic-surgery-on-esophageal-motor-function-evaluation-by-high-resolution-manometry
#6
Anja Wäsche, Arne Kandulski, Peter Malfertheiner, Sandra Riedel, Patrick Zardo, Thomas Hachenberg, Jens Schreiber
BACKGROUND: Alteration of esophageal function is a potential risk factor for postoperative complications in thoracic surgery. This prospective study investigates esophageal motility and function during and after thoracic procedures via high resolution manometry (HRM) and impedance technology with spatiotemporal representation of pressure data. METHODS: Twelve consecutive patients eligible for elective thoracic surgery underwent preoperative and postoperative (48 hours and 7 days) esophageal HRM...
June 2017: Journal of Thoracic Disease
https://www.readbyqxmd.com/read/28734171/muscle-synergies-reveal-impaired-trunk-muscle-coordination-strategies-in-individuals-with-thoracic-spinal-cord-injury
#7
Matija Milosevic, Hikaru Yokoyama, Murielle Grangeon, Kei Masani, Milos R Popovic, Kimitaka Nakazawa, Dany H Gagnon
Spinal cord injury (SCI) can result in paralysis of trunk muscles, which can affect sitting balance. The objective of this study was to analyze trunk muscle coordination of individuals with thoracic SCI and compare it to able-body individuals. A total of 27 individuals were recruited and subdivided into: (a) high thoracic SCI; (b) low thoracic SCI; and (c) able-body groups. Participants were seated and asked to lean their trunk in eight directions while trunk muscle activity was recorded. Muscle coordination was assessed using the non-negative matrix factorization (NMF) method to extract muscle modules, which are the synergistic trunk muscle activations, and their directional activation patterns...
July 1, 2017: Journal of Electromyography and Kinesiology
https://www.readbyqxmd.com/read/28733210/threat-effects-on-human-oculo-motor-function
#8
E N Naranjo, T W Cleworth, J H J Allum, J T Inglis, J Lea, B D Westerberg, M G Carpenter
Neuro-anatomical evidence supports the potential for threat-related factors, such as fear, anxiety and vigilance, to influence brainstem motor nuclei controlling eye movements, as well as the vestibular nuclei. However, little is known about how threat influences human ocular responses, such as eye saccades (ES), smooth pursuit eye tracking (SP), and optokinetic nystagmus (OKN), and whether these responses can be facilitated above normal baseline levels with a natural source of threat. This study was designed to examine the effects of height-induced postural threat on the gain of ES, SP and OKN responses in humans...
July 18, 2017: Neuroscience
https://www.readbyqxmd.com/read/28723718/three-dimensional-head-mounted-gaming-task-procedure-maximizes-effects-of-vestibular-rehabilitation-in-unilateral-vestibular-hypofunction-a-randomized-controlled-pilot-trial
#9
Alessandro Micarelli, Andrea Viziano, Ivan Augimeri, Domenico Micarelli, Marco Alessandrini
Considering the emerging advantages related to virtual reality implementation in clinical rehabilitation, the aim of the present study was to discover possible (i) improvements achievable in unilateral vestibular hypofunction patients using a self-assessed head-mounted device (HMD)-based gaming procedure when combined with a classical vestibular rehabilitation protocol (HMD group) as compared with a group undergoing only vestibular rehabilitation and (ii) HMD procedure-related side effects. Therefore, 24 vestibular rehabilitation and 23-matched HMD unilateral vestibular hypofunction individuals simultaneously underwent a 4-week rehabilitation protocol...
July 18, 2017: International Journal of Rehabilitation Research. Revue Internationale de Recherches de Réadaptation
https://www.readbyqxmd.com/read/28712015/mechanisms-contributing-to-reduced-knee-stiffness-during-movement
#10
Daniel Ludvig, Maciej Plocharski, Piotr Plocharski, Eric J Perreault
The ability to modulate the mechanical properties of our limbs contributes to our ability to interact with the physical world in a consistent and predictable manner. An individual joint's contributions to whole limb mechanics can be quantified by its joint impedance, which characterizes the torque generated about a joint in response to external perturbations of position. A number of studies have estimated joint impedance during movement and have shown that it can be much lower than it is during posture. However, the mechanisms contributing to these differences remain unknown partly because conditions known to affect impedance, including muscle activation and joint angles, have not been carefully controlled across studies...
July 15, 2017: Experimental Brain Research. Experimentelle Hirnforschung. Expérimentation Cérébrale
https://www.readbyqxmd.com/read/28649196/estimation-of-time-varying-intrinsic-and-reflex-dynamic-joint-stiffness-during-movement-application-to-the-ankle-joint
#11
Diego L Guarín, Robert E Kearney
Dynamic joint stiffness determines the relation between joint position and torque, and plays a vital role in the control of posture and movement. Dynamic joint stiffness can be quantified during quasi-stationary conditions using disturbance experiments, where small position perturbations are applied to the joint and the torque response is recorded. Dynamic joint stiffness is composed of intrinsic and reflex mechanisms that act and change together, so that nonlinear, mathematical models and specialized system identification techniques are necessary to estimate their relative contributions to overall joint stiffness...
2017: Frontiers in Computational Neuroscience
https://www.readbyqxmd.com/read/28638331/monosynaptic-stretch-reflex-fails-to-explain-the-initial-postural-response-to-sudden-lateral-perturbations
#12
Andreas Mühlbeier, Christian Puta, Kim J Boström, Heiko Wagner
Postural reflexes are essential for locomotion and postural stability, and may play an important role in the etiology of chronic back pain. It has recently been theoretically predicted, and with the help of unilateral perturbations of the trunk experimentally confirmed that the sensorimotor control must lower the reflex amplitude for increasing reflex delays to maintain spinal stability. The underlying neuromuscular mechanism for the compensation of postural perturbations, however, is not yet fully understood...
2017: Frontiers in Human Neuroscience
https://www.readbyqxmd.com/read/28626326/effects-of-measurement-posture-and-stimulation-intensity-on-the-nociceptive-flexion-reflex-riii-reflex
#13
Jeong-Woo Lee, Se-Won Yoon
[Purpose] The purpose of this study was to examine the effects of the measurement posture and stimulation intensity on the nociceptive flexion reflex (RIII reflex). [Subjects and Methods] Thirty normal female adult subjects were selected for this study. Their RIII reflexes were measured in three positions and with three degrees of stimulation intensity. The measurement posture was randomly selected. The analysis items were the stimulation intensity of the induced RIII reflex, the amplitude of the RIII reflex, and the numeric rating scale (NRS)...
June 2017: Journal of Physical Therapy Science
https://www.readbyqxmd.com/read/28610582/behavioral-and-neural-adaptations-in-response-to-five-weeks-of-balance-training-in-older-adults-a-randomized-controlled-trial
#14
Jan Ruffieux, Audrey Mouthon, Martin Keller, Michael Wälchli, Wolfgang Taube
BACKGROUND: While the positive effect of balance training on age-related impairments in postural stability is well-documented, the neural correlates of such training adaptations in older adults remain poorly understood. This study therefore aimed to shed more light on neural adaptations in response to balance training in older adults. METHODS: Postural stability as well as spinal reflex and cortical excitability was measured in older adults (65-80 years) before and after 5 weeks of balance training (n = 15) or habitual activity (n = 13)...
June 13, 2017: Journal of Negative Results in Biomedicine
https://www.readbyqxmd.com/read/28589244/does-spinal-excitability-scale-to-the-difficulty-of-the-dual-task
#15
Devon M Day, Mario T Boivin, Allan L Adkin, Craig D Tokuno
PURPOSE: This study examined whether spinal excitability, as measured by the soleus Hoffmann reflex (H-reflex), is scaled to the difficulty level of the dual-task being performed. METHODS: Twenty-two participants completed a combination of three balance task and three secondary cognitive (visuo-motor) task difficulty levels for a total of nine dual-task conditions. An additional eight participants were tested while performing the same three balance task difficulty levels on its own (i...
August 2017: European Journal of Applied Physiology
https://www.readbyqxmd.com/read/28586619/role-of-stretching-exercises-in-the-management-of-constipation-in-spastic-cerebral-palsy
#16
Waqar Ahmed Awan, Tahir Masood
BACKGROUND: Constipation is considered as one of the most common non-motor manifestations in cerebral palsy (CP). Along with other reasons, spasticity also contributes in developing constipation in CP, by decreasing mobility of trunk and lower extremities and abdominal viscera. Stretching exercises of upper extremities, trunk and lower extremities are routine management of spasticity in CP children. The objective of the study was to determine the role of stretching exercises in improving constipation symptoms in children with spastic cerebral palsy and to explore the association between spasticity and constipation among cerebral palsy children...
October 2016: Journal of Ayub Medical College, Abbottabad: JAMC
https://www.readbyqxmd.com/read/28582897/reflex-mediated-dynamic-neuromuscular-stabilization-in-stroke-patients-emg-processing-and-ultrasound-imaging
#17
Hyun S Yoon, Joshua Sung H You
BACKGROUND: Postural core instability is associated with poor dynamic balance and a high risk of serious falls. Both neurodevelopmental treatment (NDT) and dynamic neuromuscular stabilization (DNS) core stabilization exercises have been used to improve core stability, but the outcomes of these treatments remain unclear. OBJECTIVE: This study was undertaken to examine the therapeutic effects of NDT and DNS core stabilization exercises on muscular activity, core stability, and core muscle thickness...
July 20, 2017: Technology and Health Care: Official Journal of the European Society for Engineering and Medicine
https://www.readbyqxmd.com/read/28515977/establishing-normative-change-values-in-visual-acuity-loss-during-the-dynamic-visual-acuity-test
#18
Chris Marquez, Monica Lininger, Scot Raab
BACKGROUND: Baseline visual acuity (VA) loss from static to dynamic head conditions assessed using the Dynamic Visual Acuity Testing (DVAT) have not been established in NCAA football players. DVAT assesses the Vestibulo-Ocular Reflex (VOR) which is measured in Logarithm of the Minimum Angle of Resolution (logMAR). Decreased VA beyond baseline measures may detect VOR impairment and impact treatment protocols and assist in return to play decisions post-concussion. HYPOTHESIS/PURPOSE: To establish normative VA mean scores during a static head posture as well as dynamically during the DVAT with a head speed of 150 deg/s in the pitch (vertical) and yaw (horizontal) planes rotating 20 degrees in each direction...
April 2017: International Journal of Sports Physical Therapy
https://www.readbyqxmd.com/read/28495941/pontomesencephalic-atrophy-and-postural-instability-in-wilson-disease
#19
J Kalita, S Naik, S K Bhoi, U K Misra, A Ranjan, S Kumar
BACKGROUND AND PURPOSE: The MR Parkinsonism index helps in differentiating progressive supranuclear palsy from Parkinson disease and multisystem atrophy. Pontomesencephalic involvement is common in neurologic Wilson disease, but there is no prior study evaluating the MR Parkinsonism index and its indices in Wilson disease. We report the MR Parkinsonism index and its indices in Wilson disease and correlate these changes with clinical severity and postural reflex. MATERIALS AND METHODS: Thirteen individuals with neurologic Wilson disease were included, and their clinical details, including neurologic severity, postural reflex abnormality, and location of signal changes on MR imaging, were noted...
May 11, 2017: AJNR. American Journal of Neuroradiology
https://www.readbyqxmd.com/read/28462674/validity-and-reliability-of-smartphone-applications-for-clinical-assessment-of-the-neuromusculoskeletal-system
#20
Aliaa Rehan Youssef, Mohammed Gumaa
Clinicians increasingly use smartphone medical applications. There is no evidence to support the validity and reliability of applications used to assess the neuromusculoskeletal system. The aim of this study was to systematically review the quality of studies as well as the validity and reliability of using a smartphone as a clinical assessment tool for the neuromusculoskeletal system. Areas covered: PubMed, CINAHL and Embase were searched. A manual search was also conducted. Additionally, forward snowballing of relevant articles was performed in Scopus and Web of Science...
June 2017: Expert Review of Medical Devices
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