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Postural Reflex

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https://www.readbyqxmd.com/read/28061922/respiratory-and-pulse-changes-due-to-vestibular-stimulations-in-a-motion-based-simulator
#1
Savas Ilbasmis, Safak Yildiz
INTRODUCTION: One of the mechanisms leading to spatial disorientation (SD) is overstimulation of the vestibular system by various aircraft maneuvers. The objective of this study was to observe respiratory rate and pulse changes during vestibular system stimulations with the help of two selected SD training profiles. METHODS: The respiration and pulse rates of 15 subjects were recorded in response to 2 sequential SD training profiles on a motion-based simulator. The session started with a motionless instruction period (IP), continued with a Coriolis profile (CP) which stimulated the semicircular canals, and ended with a Dark Takeoff profile (DP) which stimulated the otolith organs...
January 1, 2017: Aerospace Medicine and Human Performance
https://www.readbyqxmd.com/read/28061380/postural-response-characterization-of-standing-humans-to-multi-directional-predictable-and-unpredictable-perturbations-to-the-arm
#2
Ali Forghani, Richard Preuss, Theodore Milner
When the arm of a standing human is perturbed in an unpredictable direction, postural muscles are activated at latencies as short as 50-110ms. While the motion of the body clearly progresses in hand-to-leg sequence, there is no systematic muscle activation sequence from the arm to the leg muscles, suggesting that the activation of the muscles is not likely the result of local stretch reflexes. In fact, the lower limb muscles are activated before the upright posture is significantly disturbed. The short-latency activation amplitude and the activation probability are clearly tuned to the direction of the arm perturbation for both rostral and caudal muscles...
December 20, 2016: Journal of Electromyography and Kinesiology
https://www.readbyqxmd.com/read/28054910/examining-effects-of-physical-exertion-on-the-dynamic-visual-acuity-test-in-collegiate-athletes
#3
Jessie N Patterson, Anna M Murphy, Julie A Honaker
BACKGROUND: Acute symptoms of dizziness and/or imbalance commonly experienced in athletes postconcussion are speculated to arise from dysfunction at multiple levels (i.e., inner ear or central vestibular system) to appropriately integrate afferent sensory information. Disruption along any pathway of the balance system can result in symptoms of dizziness, decreased postural control function (vestibulospinal reflex), and reduced vestibulo-ocular reflex function. This may also lead to decreased gaze stability with movements of the head and may account for symptoms of blurred vision or diplopia reported in almost half of athletes sustaining a concussion...
January 2017: Journal of the American Academy of Audiology
https://www.readbyqxmd.com/read/28025116/perceived-timing-of-a-postural-perturbation
#4
Julian Lupo, Michael Barnett-Cowan
Falling down is a common event that threatens the survival of an organism. Simple, yet sophisticated neural mechanisms allow for rapid detection of a fall as well as the generation of compensatory reflexes designed to prevent a fall. Fall awareness and preventative alerting devices could potentially mitigate the likelihood of a fall, however, relatively little is known about the perceived timing of a fall. Common anecdotal reports suggest that humans often describe distortions in their perception of time with very little recollection of what occurred during the fall...
December 24, 2016: Neuroscience Letters
https://www.readbyqxmd.com/read/27911755/transformation-of-vestibular-signals-for-the-control-of-standing-in-humans
#5
Patrick A Forbes, Billy L Luu, H F Machiel Van der Loos, Elizabeth A Croft, J Timothy Inglis, Jean-Sébastien Blouin
: During standing balance, vestibular signals encode head movement and are transformed into coordinates that are relevant to maintaining upright posture of the whole body. This transformation must account for head-on-body orientation as well as the muscle actions generating the postural response. Here, we investigate whether this transformation is dependent upon a muscle's ability to stabilize the body along the direction of a vestibular disturbance. Subjects were braced on top of a robotic balance system that simulated the mechanics of standing while being exposed to an electrical vestibular stimulus that evoked a craniocentric vestibular error of head roll...
November 9, 2016: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/27898007/limb-remote-ischemic-postconditioning-reduces-ischemia-reperfusion-injury-by-inhibiting-nadph-oxidase-activation-and-myd88-traf6-p38map-kinase-pathway-of-neutrophils
#6
Gangling Chen, Xinyi Ye, Jiangwei Zhang, Tingli Tang, Lin Li, Peirong Lu, Qi Wu, Boyang Yu, Junping Kou
Limb remote ischemic postconditioning (LRIP) has been confirmed to reduce the ischemia-reperfusion injury but its mechanisms are still not clear. This study clarified the mechanism of LRIP based on the nicotinamide-adenine dinucleotide phosphate (NADPH) oxidase and Myeloid differentiation factor 88 (MyD88)-Tumor necrosis factor (TNF) receptor-associated factor 6 (TRAF6)-P38 pathway of neutrophils. Rat middle cerebral artery occlusion (MCAO) model was used in this study. Ischemia-reperfusion injury was carried out by MCAO 1...
November 25, 2016: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/27895569/influence-of-lumbar-muscle-fatigue-on-trunk-adaptations-during-sudden-external-perturbations
#7
Jacques Abboud, François Nougarou, Arnaud Lardon, Claude Dugas, Martin Descarreaux
Introduction: When the spine is subjected to perturbations, neuromuscular responses such as reflex muscle contractions contribute to the overall balance control and spinal stabilization mechanisms. These responses are influenced by muscle fatigue, which has been shown to trigger changes in muscle recruitment patterns. Neuromuscular adaptations, e.g., attenuation of reflex activation and/or postural oscillations following repeated unexpected external perturbations, have also been described. However, the characterization of these adaptations still remains unclear...
2016: Frontiers in Human Neuroscience
https://www.readbyqxmd.com/read/27861895/effects-of-postural-change-from-supine-to-head-up-tilt-on-the-skin-sympathetic-nerve-activity-component-synchronised-with-the-cardiac-cycle-in-warmed-men
#8
Yu Ogawa, Yoshi-Ichiro Kamijo, Shigeki Ikegawa, Shizue Masuki, Hiroshi Nose
KEY POINTS: Humans are unique in controlling body temperature in a hot environment by a large amount of skin blood flow; however, the decrease in total peripheral resistance due to systemic cutaneous vasodilatation and the reduction of venous return to the heart due to blood pooling in the cutaneous vein threatens blood pressure maintenance in the upright position, and occasionally causes heat syncope. Against this condition, cutaneous vasodilatation is reportedly suppressed to maintain arterial pressure; however, the nerve activity responsible for this phenomenon has not been identified...
November 8, 2016: Journal of Physiology
https://www.readbyqxmd.com/read/27848255/prognostic-predictors-for-ambulation-in-children-with-cerebral-palsy-a-systematic-review-and-meta-analysis-of-observational-studies
#9
Orawan Keeratisiroj, Nuanlaor Thawinchai, Wantana Siritaratiwat, Montana Buntragulpoontawee, Chayanin Pratoomsoot
PURPOSE: The purpose of this study is to investigate the prognostic predictors for ambulation in children with cerebral palsy using meta-analysis of observational studies. METHOD: Electronic searches were conducted in PubMed, SCOPUS, CINAHL, ProQuest, Ovid, Wiley InterScience, and ScienceDirect databases from their start dates to December 2015. RESULTS: Of the 1123 identified articles, 12 met the inclusion criteria for qualitative synthesis, eight of which were deemed appropriate for meta-analysis...
November 16, 2016: Disability and Rehabilitation
https://www.readbyqxmd.com/read/27834670/resistance-training-with-instability-is-more-effective-than-resistance-training-in-improving-spinal-inhibitory-mechanisms-in-parkinson-s-disease
#10
Carla Silva-Batista, Eugenia Casella Tavares Mattos, Daniel M Corcos, Jessica M Wilson, Charles J Heckman, Hélcio Kanegusuku, Maria Elisa Pimentel Piemonte, Marco Túlio de Mello, Cláudia Forjaz, Hamilton Roschel, Valmor Tricoli, Carlos Ugrinowitsch
: This study assessed 1) the effects of 12 wk of resistance training (RT) and resistance training with instability (RTI) on presynaptic inhibition (PSI) and disynaptic reciprocal inhibition (DRI) of patients with Parkinson's disease (PD); 2) the effectiveness of RT and RTI in moving PSI and DRI values of patients toward values of age-matched healthy controls (HC; Z-score analysis); and 3) associations between PSI and DRI changes and clinical outcomes changes previously published. Thirteen patients in RT group, 13 in RTI group, and 11 in a nonexercising control group completed the trial...
January 1, 2017: Journal of Applied Physiology
https://www.readbyqxmd.com/read/27834583/spinal-cord-injury-and-seated-postural-control-a-test-of-the-rambling-and-trembling-hypothesis
#11
Sunghoon Shin, Jacob J Sosnoff
Rambling-trembling analysis separates the center of pressure (COP) into two components: the rambling component (RM: supraspinal) and trembling component (TM: muscle stiffness/reflex). We hypothesized that persons with spinal cord injury (SCI) would demonstrate decreased RM resulting from altered supraspinal processing and increased TM resulting from increased muscle stiffness. We also anticipated that the TM component would be greater in SCI patients with Harrington rods than in those without them. The seated postural control was assessed in 18 persons with spinal cord injury (SCI), comprising of 12 with and 6 without Harrington rods, and 18 age-matched controls...
November 11, 2016: Motor Control
https://www.readbyqxmd.com/read/27803120/cardiovascular-autonomic-neuropathy-and-cardiovascular-outcomes-in-the-diabetes-control-and-complications-trial-epidemiology-of-diabetes-interventions-and-complications-dcct-edic-study
#12
Rodica Pop-Busui, Barbara H Braffett, Bernie Zinman, Catherine Martin, Neil H White, William H Herman, Saul Genuth, Rose Gubitosi-Klug
OBJECTIVE: To examine whether cardiovascular autonomic neuropathy (CAN) is an independent risk factor of cardiovascular disease (CVD) events during DCCT/EDIC. RESEARCH DESIGN AND METHODS: Standardized cardiovascular autonomic reflex tests (R-R response to paced breathing, Valsalva maneuver, postural changes in blood pressure) were performed at DCCT baseline, every 2 years throughout DCCT, and at two time points in EDIC. CVD events were ascertained throughout the study and adjudicated by a review committee...
January 2017: Diabetes Care
https://www.readbyqxmd.com/read/27788536/improving-the-identification-of-neonatal-encephalopathy-utility-of-a-web-based-video-tool
#13
Autumn S Ivy, Catherine L Clark, Sarah M Bahm, Krisa P Van Meurs, Courtney J Wusthoff
Objective This study tested the effectiveness of a video teaching tool in improving identification and classification of encephalopathy in infants. Study Design We developed an innovative video teaching tool to help clinicians improve their skills in interpreting the neonatal neurological examination for grading encephalopathy. Pediatric residents were shown 1-minute video clips demonstrating exam findings in normal neonates and neonates with various degrees of encephalopathy. Findings from five domains were demonstrated: spontaneous activity, level of alertness, posture/tone, reflexes, and autonomic responses...
October 27, 2016: American Journal of Perinatology
https://www.readbyqxmd.com/read/27783419/effects-of-compression-stockings-on-ankle-muscle-h-reflexes-during-standing
#14
Loic Espeit, Sebastien Pavailler, Thomas Lapole
INTRODUCTION: Wearing compression stockings (CS) may improve postural stability through additional cutaneous feedback. The aim of this study was to further determine how wearing CS could influence spinal excitability by investigating ankle muscle H-reflexes. METHODS: Fifteen subjects were asked to stand barefoot on a rigid floor with their eyes open. H-reflex amplitude was measured in the soleus (SOL), fibularis longus (FL), and tibialis anterior (TA) muscles, with and without CS...
October 26, 2016: Muscle & Nerve
https://www.readbyqxmd.com/read/27780044/evolution-of-biological-image-stabilization
#15
REVIEW
Ben J Hardcastle, Holger G Krapp
The use of vision to coordinate behavior requires an efficient control design that stabilizes the world on the retina or directs the gaze towards salient features in the surroundings. With a level gaze, visual processing tasks are simplified and behaviorally relevant features from the visual environment can be extracted. No matter how simple or sophisticated the eye design, mechanisms have evolved across phyla to stabilize gaze. In this review, we describe functional similarities in eyes and gaze stabilization reflexes, emphasizing their fundamental role in transforming sensory information into motor commands that support postural and locomotor control...
October 24, 2016: Current Biology: CB
https://www.readbyqxmd.com/read/27775527/identification-of-a-time-varying-box-jenkins-model-of-intrinsic-joint-compliance
#16
Diego L Guarin, Robert E Kearney
The mechanical properties of a joint are determined by the combination of intrinsic and reflex mechanisms. However, in some situations the reflex contributions are small so that intrinsic mechanisms play the dominant role in the control of posture and movement. The intrinsic mechanisms, characterized by the joint compliance, can be described well by a second order, linear model for small perturbations around an operating point defined by mean position and torque. However, the compliance parameters depend strongly on the operating point...
October 19, 2016: IEEE Transactions on Neural Systems and Rehabilitation Engineering
https://www.readbyqxmd.com/read/27734621/clinical-approach-to-autonomic-dysfunction
#17
R Wells, A Tonkin
Patients with autonomic dysfunction may present with a variety of seemingly unrelated symptoms, both generalised and involving specific systems, including fatigue, difficulty concentrating, orthostatic intolerance, palpitations, constipation or diarrhoea, early satiety, urinary retention or incontinence and erectile dysfunction. Failure to connect the diverse symptoms with a single underlying mechanism may lead to incorrect diagnoses, inappropriate interventions and frustration on the part of both doctors and patients...
October 2016: Internal Medicine Journal
https://www.readbyqxmd.com/read/27720003/epidemiology-of-parkinson-disease
#18
REVIEW
Andrea Lee, Rebecca M Gilbert
Parkinson disease (PD) is a common progressive neurodegenerative condition, causing both motor and non motor symptoms. Motor symptoms include stiffness, slowness, rest tremor and poor postural reflexes, whereas nonmotor symptoms include abnormalities of mood, cognition, sleep and autonomic function. Affected patients show cell loss in the substantia nigra pars compacta, and accumulation of aggregated alpha-synuclein into intracellular structures called Lewy bodies, within specific brain regions. The main known non modifiable risk factor is age...
November 2016: Neurologic Clinics
https://www.readbyqxmd.com/read/27718070/neurological-assessment-of-chinese-infants-with-positional-plagiocephaly-using-a-chinese-version-of-the-infant-neurological-international-battery-infanib
#19
Xue-Qing Zhao, Li-Yan Wang, Cong-Min Zhao, Qing Men, Zhi-Feng Wu, Yu-Ping Zhang
PURPOSE: Positional plagiocephaly (PP) is the most common subtype of asymmetric deformity in the infant skull. Cumulative evidence has demonstrated that PP is associated with abnormal neuromotor development; however, neurological assessment scores of infants with PP have not been well established, and PP has not attracted sufficient attention in China. This study used a Chinese version of the Infant Neurological International Battery (INFANIB) to identify neurological abnormalities among infants with PP and to determine the differences between infants with different (mild, moderate, and severe) degrees of PP...
October 7, 2016: Child's Nervous System: ChNS: Official Journal of the International Society for Pediatric Neurosurgery
https://www.readbyqxmd.com/read/27702647/effect-of-acute-lateral-hemisection-of-the-spinal-cord-on-spinal-neurons-of-postural-networks
#20
P V Zelenin, V F Lyalka, G N Orlovsky, T G Deliagina
In quadrupeds, acute lateral hemisection of the spinal cord (LHS) severely impairs postural functions, which recover over time. Postural limb reflexes (PLRs) represent a substantial component of postural corrections in intact animals. The aim of the present study was to characterize the effects of acute LHS on two populations of spinal neurons (F and E) mediating PLRs. For this purpose, in decerebrate rabbits, responses of individual neurons from L5 to stimulation causing PLRs were recorded before and during reversible LHS (caused by temporal cold block of signal transmission in lateral spinal pathways at L1), as well as after acute surgical LHS at L1...
December 17, 2016: Neuroscience
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