stretch reflex

..A mean stretch reflex (SR) amplitude ((-)SRA), i.e...

..However, these results support the theory that the interaction of central mechanisms and peripheral events may be responsible for clonus...

Spasticity is a disorder of hypertonus associated with neurological diseases, characterized by a decrease in stretch reflex threshold...

..These results provide evidence that the gain of the gamma loop is increased during fatigue, indicating possible peripheral neural compensation to the motor neuron pool in order to preserve force output...

..With pain in the soleus muscle the mechanical stretch reflex response (ankle torque) increased significantly (P = 0.0007) as compared to before pain...

..of the human medial gastrocnemius (MG) muscle was monitored to evaluate possible input from the short-latency stretch reflex (SLR) during the stance phase of running and to examine its timing at various running speeds...

..in contraction intensity in the human triceps surae and to relate fascicle stretch responses to short-latency stretch reflex behavior...

..Unilateral lesions of the dorsolateral funiculus (DLF) produced significant ipsilateral decreases in stretch reflex threshold and increases in reflex gain, measured as incremental dynamic stiffness (IDS)...

The aim of the study was to measure stretch reflex latencies of the lumbar paraspinal muscles...

The purpose of this study was to investigate the effects of hip proprioceptors on soleus stretch reflex excitability in standing humans...

..activation of nociceptive muscle afferent fibers would be linked to an increased excitability of the human jaw-stretch reflex and whether this process would be sensitive to length and velocity of the stretch...

A long-latency stretch reflex (LLSR) has been described in the human masseter muscle, but its pathway remains uncertain...

..perturbations were delivered during slow voluntary finger movements with the aim of exploring the role of the stretch reflex in generating the 8-10 Hz discontinuities that characterize these movements...

..of this study was to determine which afferents contribute to the medium latency response of the soleus stretch reflex resulting from an unexpected perturbation during human walking. 2...

..controversy within the literature regarding the influence of task instruction on the size of the long-latency stretch reflex (M2) elicited by a joint displacement...

Irvin M. Korr, PhD, hypothesized that sensitivity of the monosynaptic stretch reflex (ie, deep tendon reflex) plays a major role in the restriction-of-motion characteristic of somatic dysfunction, and that restoration of range of motion ..

..These afferents are activated preferentially as muscles are stretched to near maximum length, and they appear to have potent reflex effects in spinal cord injury...

Spasticity is defined/assessed in resting limbs, where increased stretch reflex activity and mechanical joint resistance are evident...

..These changes affect not only MEPs and SEPs but also EMG responses to more 'natural' inputs involved in transcortical stretch reflexes...

..reflexes where excellent temporal resolution is required to identify the different latency components, and on the tonic stretch reflex (tonic SR) response to an ongoing perturbation that characteristically has a low signal to noise ratio.

Different neural pathways are proposed to mediate the long-latency stretch reflex response (M2) in muscles spanning distal and proximal joints of the upper limb...

..It was concluded that the stretch duration effect of the M2 likely originates from the proposed Ia afferent mediated mechanism...

..To review and characterise biomechanical approaches for the measurement of spasticity as one component of the upper motor neurone syndrome...

The modulation of the short latency stretch reflex of the soleus muscle during walking was investigated in seven spastic multiple sclerosis (MS) patients and nine healthy control subjects...

1. The human stretch reflex is known to produce a phase advance in the EMG reflexly evoked by sinusoidal stretching, after allowing for the phase lag introduced by simple conduction...

..The purpose of this study was to investigate the specificity of stretch reflex modulation during interactions with mechanical environments that challenge arm stability...

..active muscle system around the joint (termed the non-reflex component), ii) the mechanical importance of the stretch reflex in the stretched and unloaded muscles, and iii) the supraspinal control of the stretch reflex...

..This study investigated the effects of phase of the cardiac cycle and arousal on the muscle stretch reflex components M1, M2, and M3...

..b>Stretch reflex sensitivity increased significantly in all muscles during interactions with the compliant environment and ..

..suggest that an increase in sympathetic outflow can depress muscle spindle sensitivity and thus modulate the stretch reflex response...

..It is concluded that reflex stiffness can be large enough to be important functionally, but that its effects will depend strongly upon the particular conditions...

This paper reports an investigation of the magnitude and timing of the stretch reflex over the full range of activation of flexor carpi radialis...

..05). The decrease in MVC during post-test(1) was attributed to changes in the mechanical properties of PF and not to reduced muscle activation...

..first to compare the kinematic parameters of imposed ankle mobilizations measured during Ashworth or isokinetic tests and, second, to better understand why the stretch reflex was more or less easily elicited by one method or the other.

..neurophysiological methods to assess spasticity with respect to mechanisms and methodology, and to describe the three most commonly used methods: the Hoffmann reflex (H-reflex), the Tendon reflex (T-reflex), and the Stretch Reflex (SR).

..Part III explores the proposed sensorimotor mechanisms underlying the control of landing. The review concludes with as yet unresolved questions and directions for future research...

AIM: To examine whether the stretch reflex excitability of the soleus muscle changes with age, stretch reflexes at rest (REST) and during weak voluntary contractions (ACT) were elicited in 18 older and 14 younger subjects...

..Results agree with a simple systems model of the neuromechanical feedback behavior. The relative contribution of the reflex dynamics to spinal stability must be investigated in future research...

..It was also concluded that this control strategy was near optimal when mediated by joint afferents...

..Both active models and the passive model use separate parameters of stiffness and damping for the agonist and antagonist muscles...

..Further, following contraction of a stretched muscle, inhibition of the stretch reflex response lasts only 1 s...

..In addition, altered material properties seem to affect proprioceptive feedback and, therefore, the motor unit activation in proportion to the contractile failure...

The purpose of this study was to investigate the transcortical nature of the long-latency stretch reflex (M3) in the human tibialis anterior muscle...

..Possible mechanisms underlying these changes in neural organization are discussed. SPONSORSHIP: This study was supported by Spinal Cord Research Foundation, the Paralyzed Veterans of America...

..limit of range of motion, gravitational field, and muscular torques due to voluntary activation as well as to stretch reflex depending on fusal afferences...

..This study implemented a unique hydraulic actuator to study the contributions of the knee extensor stretch reflex to the overall knee joint torque...

..Such markers could have diagnostic and prognostic value in relation to the recovery of locomotion in patients with central motor lesions...

..The reasons for a differential impairment of intrafusal and extrafusal muscle fibers and the clinical implications of the present results are discussed...

..Frequency of occurrence and latency of stretch reflex (SR) and ShoRe, and RTs were measured from the electromyograms (EMG) of wrist flexor (FCR) and extensor (ECR) ..

..of joints to passive rotation and the possible origin of this increased resistance in the induced tonic stretch reflex (TSR)...

A rupture of the anterior cruciate ligament (ACL) usually leads to an altered stretch reflex excitability of the thigh muscles that stabilize the knee. The purpose of this study was to quantitatively assess reflex activity in the m...

The influence of pedaling frequency and crank load on the sensitivity of the soleus short latency stretch reflex (SLR) was examined in nine healthy subjects during pedaling by the use of a custom-built robotic actuator...

..The results indicate that the anticipation of an applied perturbation torque decreases the onset time of the reflex response in the Bb and Tb...

..We conclude that the X-VR-D is safe and effective to elicit consistent and reproducible muscle activity in trunk and leg muscles in healthy subjects and thus can be used as a training method...

..Results from this case study support clinically identified task-specific feature of focal hand dystonia...

..Thus, we conclude that the CNS can control reflex stiffness independently and so has great flexibility in adjusting the mechanical properties of a joint to meet functional requirements...

..The SOL short-latency stretch reflex was facilitated in the patients (1.4 +/- 0.3) compared with the healthy volunteers (1.0 +/- 0.3, P = .05)...

..These results suggest that age-specific muscle activation patterns as well as mechanical behaviors exist during DJs...

..Evidence of stretch reflex facilitation post-SCI may reflect changes in underlying neuronal properties and provide insight into the ..

..To evaluate the effect of massage on force production and neuromuscular recruitment...

..The first is reduced excitability of monosynaptic connections in the motor neuron pool, which is related to weakness. The other is the presence of ILR as an indicator of interneuronal hyper-excitability, which is not related to weakness...

It is known that the short-latency stretch reflex (SLSR) is modulated by the background muscle activity when it is elicited at matched torque levels...

..However, they are compatible with the idea of peripheral factors, such as peripheral muscle and tendon elasticity, playing a major potentiating role in the SSC...

..Next, multiple elements in the sensorimotor circuit of the stretch reflex were examined in both the PNS and CNS...

..the effects of selective anesthetic blocks of motor nerve branches to the triceps surae muscle on lower limb stretch reflex in patients with spastic equinus foot...

..It would minimize this inhibition during the stance phase of walking and might enhance soleus muscle activity via this reflex pathway for the support of weight...

..The EMD, as a component of the stretch reflex, is important for the utilization of the stored energy in the series elastic component and thus, optimal ..

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..of this study was to compare the influence of prolonged vibration of a hand muscle on the amplitude of the stretch reflex, motor unit discharge rate, and force fluctuations during steady, submaximal contractions...

..The EMG driven model predicted well for all non-SSC trials, but significantly underestimated the work for SSC tasks, suggesting that the contractile component is directly involved in optimising muscle work during SSC tasks...

..to establish whether spastic hypertonia results from changes in intrinsic muscle properties or from altered stretch reflex properties...

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..CONCLUSIONS: It is concluded that the integrity of the Ia-motoneuron synapse as measured with a PD protocol, is different between young and elderly subjects, but that this difference is not related to postural sway...

..investigation examined the effect of various types of background muscle contractions on the short-latency stretch reflex (SLR) elicited from the soleus muscle while subjects were in a sitting position...

..The objective of this study was to investigate the contribution of load receptor feedback to the compensatory stretch reflex response...

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..Our results indicate that vestibular influences are earlier for the pitch plane and are directed to leg muscles, whereas roll control is later and focused on trunk muscles...

..valgus joint deflection in the vasti muscles had longer onset latencies (range: 83-92ms) than did the stretch reflex in the same muscles (latencies: 29-31ms)...

..The possibility that a mental computation task may also operate by reducing the level of presynaptic inhibition is discussed on the basis of H-reflex facilitation...

..falling torque) during the later part of an eccentric movement would not have occurred if a stabilizing stretch reflex had been present...

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..Later excitatory and inhibitory reflexes with central delays of up to 15 ms also occurred. The probability of evoking excitation or inhibition in Tri or Bi changed with the different elbow positions...

..This is a unique demonstration of how a stretch reflex operates to maintain posture under entirely natural conditions.

Operant conditioning of the spinal stretch reflex or its electrical analog, the H-reflex, produces spinal cord plasticity and can thereby affect motoneuron responses to primary afferent input...

Operant conditioning of the H-reflex, the electrical analog of the spinal stretch reflex, is a simple model of skill acquisition and involves plasticity in the spinal cord...

Operant conditioning of the spinal stretch reflex or its electrical analog, the H-reflex, is a new model for exploring the mechanisms of long-term supraspinal control over spinal cord function...

..excessive sympathetic activation, increased respiratory tidal volume, and fainting involving the pulmonary stretch reflex. We studied 18 patients 13-21 yr old, 11 who fainted within 10 min of upright tilt (fainters) and 7 healthy ..

..The trunk extended backwards at 80 ms, which was followed by forward flexion. The absent stretch reflex and weaker balance-correcting responses in patients produced changed trunk velocity profiles (mainly a reduced ..

Operant conditioning of the H-reflex, the electrical analog of the spinal stretch reflex, in freely moving rats is a relatively simple model for studying long-term supraspinal control over spinal cord function...

In comparison to the H-reflex, the task dependency of the human stretch reflex during locomotive and postural tasks has not received a great deal of attention in the literature...

..major spinal cord tracts, prevents down-conditioning of the H-reflex, the electrical analog of the spinal stretch reflex. This study set out to determine whether the loss of the capacity for H-reflex down-conditioning caused by CST ..

..Operant conditioning of the H-reflex, the electrical analog of the spinal stretch reflex (SSR), is a relatively simple model for exploring the spinal cord plasticity underlying this functional change ..

Rats, monkeys, and humans can alter the size of their spinal stretch reflex and its electrically induced analog, the H-reflex (HR), when exposed to an operant conditioning paradigm...

..Operant conditioning of the H-reflex, the electrical analogue of the spinal stretch reflex, is a simple model for investigating these mechanisms...

..Static stretch reflex gain decreased significantly at higher torque levels after fatigue, indicating that the isometric fatiguing ..

The effects of electrical stimulation of the sciatic nerve on background electromyographic and static stretch reflex activity of the trunk muscles were studied.

..6. The relatively large H reflex recorded during the stance phase in running indicates that the stretch reflex may influence the muscle mechanics during the stance phase by contributing to the motor output and enhancing ..

The motor system responds to perturbations with reflexes, such as the vestibulo-ocular reflex or stretch reflex, whose gains adapt in response to novel and fixed changes in the environment, such as magnifying spectacles or standing on a ..

..by the rectosigmoid pacemaker, while that of the circular muscle fibers is believed to be initiated by the stretch reflex induced by rectal distension...

..The spinal stretch reflex (SSR), or tendon jerk, which is mediated by a wholly spinal and largely monosynaptic pathway, is a model that ..

..reflecting a loss of independent joint control, and hyperactivity of spinal reflexes, including the stretch reflex (spasticity)...

..This requires models based on simple skills produced by defined and accessible neural circuitry. The spinal stretch reflex (SSR or tendon jerk) satisfies this requirement. Its spinal pathway is influenced by the brain...

..Altered spinal reflex pathways contribute to these problems. In this population, exaggerated stretch reflex and abnormal reflex modification of the ankle extensors are frequently observed...

..The spinal stretch reflex (SSR or tendon jerk) satisfies this requirement...

..The spinal stretch reflex (SSR or tendon jerk) satisfies this requirement...

..reflecting a loss of independent joint control, and hyperactivity of spinal reflexes, including the stretch reflex (spasticity)...

..reflecting a loss of independent joint control, and hyperactivity of spinal reflexes, including the stretch reflex (spasticity)...

..This requires models based on simple skills produced by defined and accessible neural circuitry. The spinal stretch reflex (SSR or tendon jerk) satisfies this requirement. Its spinal pathway is influenced by the brain...

..This requires models based on simple skills produced by defined and accessible neural circuitry. The spinal stretch reflex (SSR or tendon jerk) satisfies this requirement. Its spinal pathway is influenced by the brain...

..The long-term goals are to provide effective, convenient, and low-cost treatments of spastic limbs in neurologically impaired patients with quantitative outcome evaluation in multiple aspects. ..

..The H-reflex is the electrical analog of the spinal stretch reflex. Conditioned H-reflex change remains even after all supraspinal input is removed...

..of the simplest behavior of the vertebrate CNS, the H- reflex, which is the electrical analog of the spinal stretch reflex. Once an animal has been conditioned, the reflex change persists even if all supraspinal input is removed...

..We will look for differences in stretch reflex EMG, spindle afferent, motor cortex and cerebellar neuronal activities as the subjects adapt to control - and ..

..To achieve these aims, MSNA, force fluctuations, single motor unit activity, stretch reflex, and H-reflex during steady contractions of a hand muscle will be measured when MSNA is experimentally ..

..patterns, reflecting a loss of independent joint control, and hyperactivity of spinal reflexes including the stretch reflex (spasticity) and the flexion withdrawal reflex...

..is to study the development of one well characterized neuronal circuit in detail, the simple monosynaptic stretch reflex. Sensory neurons supplying stretch-sensitive spindle organs in muscles (Ia afferents) project into the spinal ..

..Synaptic transmission between muscle spindle afferents and motoneurons, the pathways that mediates the simple stretch reflex, is inhibited by stimulation of other sensory afferents...

..Operant conditioning of the spinal stretch reflex (or tendon jerk) or its electrical analog, the H-reflex, is a simple model for exploring long-term supraspinal ..

..Operant conditioning of the spinal stretch reflex (or tendon jerk) or its electrical analog, the H-reflex, is a simple model for exploring long-term supraspinal ..

..of the simplest behavior of vertebrate CNS, the H-reflex, which is the electrical analog of the spinal stretch reflex. The responsible plasticity is in the spinal cord, and H-reflex conditioning is a good model for studying the ..

..Operant conditioning of the spinal stretch reflex (or tendon jerk) or its electrical analog, the H-reflex, is a simple model for exploring long-term supraspinal ..

..Operant conditioning of the spinal stretch reflex (or tendon jerk) or its electrical analog, the H-reflex, is a simple model for exploring long-term supraspinal ..

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..This will be applicable to a large population of US adults with deficits in hand function resulting from stroke. ..