Spinal Fixation: Long-Term Alterations in Spinal Reflex Excitability with Altered or Sustained Sensory Inputs

2001 ◽  
pp. 77-99 ◽  
Author(s):  
Michael M. Patterson
Keyword(s):  
Spinal Reflex ◽  
Spinal Fixation ◽  
Sensory Inputs ◽  
Reflex Excitability

Changes in H-reflex amplitude to muscle stretch and lengthening in humans

2016 ◽  
Vol 27 (5) ◽  
pp. 511-522 ◽  
Author(s):  
Francesco Budini ◽  
Markus Tilp
Keyword(s):  
Human Movement ◽  
Careful Consideration ◽  
H Reflex ◽  
Spinal Reflex ◽  
Neural Pathways ◽  
Static Stretching ◽  
Plantar Flexors ◽  
Reflex Excitability ◽  
Apparent Disagreement ◽  
Shed Light

AbstractSpinal reflex excitability is traditionally assessed to investigate neural adjustments that occur during human movement. Different experimental procedures are known to condition spinal reflex excitability. Among these, lengthening movements and static stretching the human triceps have been investigated over the last 50 years. The purpose of this review is to shed light on several apparent incongruities in terms of magnitude and duration of the reported results. In the present review dissimilarities in neuro-spinal changes are examined in relation to the methodologies applied to condition and measure them. Literature that investigated three different conditioning procedures was reviewed: passive dorsiflexion, active dorsiflexion through antagonists shortening and eccentric plantar-flexors contractions. Measurements were obtained before, during and after lengthening or stretching. Stimulation intensities and time delays between conditioning procedures and stimuli varied considerably. H-reflex decreases immediately as static stretching is applied and in proportion to the stretch degree. During dorsiflexions the inhibition is stronger with greater dorsiflexion angular velocity and at lower nerve stimulation intensities, while it is weaker if any concomitant muscle contraction is performed. Within 2 s after a single passive dorsiflexion movement, H-reflex is strongly inhibited, and this effect disappears within 15 s. Dorsiflexions repeated over 1 h and prolonged static stretching training induce long-lasting inhibition. This review highlights that the apparent disagreement between studies is ascribable to small methodological differences. Lengthening movements and stretching can strongly influence spinal neural pathways. Results interpretation, however, needs careful consideration of the methodology applied.

scholarly journals Changes in Spinal-Reflex Excitability during Static Stretch and/or Explosive Contraction

2021 ◽  
Vol 11 (6) ◽  
pp. 2830
Author(s):  
Kyeong Eun Min ◽  
YongSuk Lee ◽  
Jihong Park
Keyword(s):  
Motor Response ◽  
Vertical Jump ◽  
Spinal Reflex ◽  
Static Stretch ◽  
Young Males ◽  
Reflex Excitability ◽  
Contraction Condition ◽  
Exercise Activity ◽  
Point Condition ◽  
The Right

To examine individual or combined effects of static stretch and explosive contraction on quadriceps spinal-reflex excitability (the peak Hoffmann’s reflex normalized by the peak motor-response) and the latency times of the Hoffmann’s reflex and motor-response. Fourteen healthy young males randomly experienced four conditions (stretch, contraction, stretch + contraction, and control—no intervention). For the stretch condition, three sets of a 30 s hold using the modified Thomas test on each leg were performed. For the contraction condition, three trials of maximal countermovement vertical jump were performed. Quadriceps spinal-reflex excitability and the latent period of each value on the right leg were compared at pre- and post-condition. All measurement values across conditions were not changed at any time point (condition × time) in spinal-reflex excitability (F6,143 = 1.10, p = 0.36), Hoffmann’s reflex latency (F6,143 = 0.45, p = 0.84), motor-response latency (F6,143 = 0.37, p = 0.90), and vertical jump heights (F2,65 = 1.82, p = 0.17). A statistical trend was observed in the contraction condition that spinal-reflex excitability was increased by 42% (effect size: 0.63). Neither static stretch nor explosive contraction changed the quadriceps spinal-reflex excitability, latency of Hoffmann’s reflex, and motor-response. Since our stretch protocol did not affect jumping performance and our contraction protocol induced the post-activation potentiation effect, either protocol could be used as pre-exercise activity.

scholarly journals Neuromuscular Function of the Knee Joint Following Knee Injuries: Does It Ever Get Back to Normal? A Systematic Review with Meta-Analyses

2020 ◽  
Author(s):  
Beyza Tayfur ◽  
Chedsada Charuphongsa ◽  
Dylan Morrissey ◽  
Stuart Charles Miller
Keyword(s):  
Systematic Review ◽  
Knee Joint ◽  
Strong Evidence ◽  
Knee Injuries ◽  
Neuromuscular Function ◽  
Spinal Reflex ◽  
Voluntary Activation ◽  
Moderate Evidence ◽  
Reflex Excitability ◽  
Meta Analyses

Abstract Background Neuromuscular deficits are common following knee injuries and may contribute to early-onset post-traumatic osteoarthritis, likely mediated through quadriceps dysfunction. Objective To identify how peri-articular neuromuscular function changes over time after knee injury and surgery. Design Systematic review with meta-analyses. Data Sources PubMed, Web of Science, Embase, Scopus, CENTRAL (Trials). Eligibility Criteria for Selecting Studies Moderate and high-quality studies comparing neuromuscular function of muscles crossing the knee joint between a knee-injured population (ligamentous, meniscal, osteochondral lesions) and healthy controls. Outcomes included normalized isokinetic strength, muscle size, voluntary activation, cortical and spinal-reflex excitability, and other torque related outcomes. Results A total of 46 studies of anterior cruciate ligament (ACL) and five of meniscal injury were included. For ACL injury, strength and voluntary activation deficits were evident (moderate to strong evidence). Cortical excitability was not affected at < 6 months (moderate evidence) but decreased at 24+ months (moderate evidence). Spinal-reflex excitability did not change at < 6 months (moderate evidence) but increased at 24+ months (strong evidence). We also found deficits in torque variability, rate of torque development, and electromechanical delay (very limited to moderate evidence). For meniscus injury, strength deficits were evident only in the short-term. No studies reported gastrocnemius, soleus or popliteus muscle outcomes for either injury. No studies were found for other ligamentous or chondral injuries. Conclusions Neuromuscular deficits persist for years post-injury/surgery, though the majority of evidence is from ACL injured populations. Muscle strength deficits are accompanied by neural alterations and changes in control and timing of muscle force, but more studies are needed to fill the evidence gaps we have identified. Better characterisation and therapeutic strategies addressing these deficits could improve rehabilitation outcomes, and potentially prevent PTOA. Trial Registration Number PROSPERO CRD42019141850.

scholarly journals Dopamine, behavior, and addiction

2021 ◽  
Vol 28 (1) ◽  
Author(s):  
Roy A. Wise ◽  
Chloe J. Jordan
Keyword(s):  
Dopaminergic Neurons ◽  
Long Term Potentiation ◽  
Burst Firing ◽  
Dopamine Neurons ◽  
Dopamine System ◽  
Learned Behavior ◽  
Sensory Inputs ◽  
Addictive Drugs ◽  
Term Potentiation

AbstractAddictive drugs are habit-forming. Addiction is a learned behavior; repeated exposure to addictive drugs can stamp in learning. Dopamine-depleted or dopamine-deleted animals have only unlearned reflexes; they lack learned seeking and learned avoidance. Burst-firing of dopamine neurons enables learning—long-term potentiation (LTP)—of search and avoidance responses. It sets the stage for learning that occurs between glutamatergic sensory inputs and GABAergic motor-related outputs of the striatum; this learning establishes the ability to search and avoid. Independent of burst-firing, the rate of single-spiking—or “pacemaker firing”—of dopaminergic neurons mediates motivational arousal. Motivational arousal increases during need states and its level determines the responsiveness of the animal to established predictive stimuli. Addictive drugs, while usually not serving as an external stimulus, have varying abilities to activate the dopamine system; the comparative abilities of different addictive drugs to facilitate LTP is something that might be studied in the future.

scholarly journals Vestibular Control of Intermediate- and Long-Term Cardiovascular Responses to Experimental Orthostasis

2010 ◽  
pp. 43-51
Author(s):  
G Raffai ◽  
C Csekő ◽  
G Nádasy ◽  
E Monos
Keyword(s):  
Wistar Rats ◽  
Cardiovascular Responses ◽  
Sensory Inputs ◽  
Average Value ◽  
Arterial Blood ◽  
Vestibular Cues ◽  
Gravitational Stress ◽  
Chemical Technique ◽  
Head Up Tilt

Sustained orthostasis elicits the elevation of arterial blood pressure (BP) via sympathetic activation in conscious Wistar rats for at least 2 hours. We tested the hypothesis whether vestibular apparatus plays a role in BP and heart rate (HR) control in response to prolonged gravitational stress. BP and HR responses to 45º head-up for either 2 or 24 hours were monitored by telemetry. Vestibular lesions (VL) were performed by a modified microsurgical-chemical technique. Horizontal BP and HR were not influenced by VL preceding 2-hour tilt. VL abolished the sustained 2-hour BP response to head-up tilt (8.3±0.9 mm Hg relative to horizontal values) while suppressed HR transiently only. VL eliminated diurnal BP fluctuations and decreased HR in horizontal position for 24 hours. Head-up tilt for 24 hours increased BP and HR progressively in intact animals, raising their daily average value by 5.6±0.7 mm Hg and 22.2±6 BPM, respectively. VL resulted in an initial BP rise followed by progressive BP reduction in response to long-term head-up tilt (4±2.2 mm Hg) without eliminating the tachycardia (34.4±5.4 BPM). Thus, blockade of labyrinthine inputs attenuates the BP responses elicited by both intermediate and long-term gravitational stress of orthostatic type. However, other sensory inputs derived from non-vestibular cues (e.g. proprioceptive, visual, visceral, cutaneous etc.) seem to be effective enough to maintain BP normal.

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