The 1989 James A. F. Stevenson Memorial Lecture. The knee jerk: still an enigma?

1990 ◽  
Vol 68 (3) ◽  
pp. 347-354 ◽  
Author(s):  
Peter B. C. Matthews
Keyword(s):  
Muscle Spindle ◽  
Stretch Reflex ◽  
Position Sense ◽  
Muscle Afferents ◽  
Normal Function ◽  
Memorial Lecture ◽  
Stretch Reflexes ◽  
Knee Jerk ◽  
Long Latency ◽  
Tendon Reflex

This is a wide-ranging review of muscle proprioceptors, intended primarily for the nonspecialist. It emphasizes how much more they are concerned with, than just the production of the knee jerk; it concentrates on principle rather than documenting detail and cites selectively. The main topics covered are the effect of deafferentation, position sense, the proprioceptors themselves, the control of the muscle spindle by the CNS, and spinal and long-latency "stretch" reflexes. The emphasis is on human work. The knee jerk itself is seen as a "physiological artefact," resulting from a mode of stimulation that does not occur in life, with the normal function of its underlying circuitry still under debate.Key words: tendon reflex, stretch reflex, muscle afferents.

The effects of cold-induced muscle spindle secondary activity on monosynaptic and stretch reflexes in the decerebrate cat

1979 ◽  
Vol 57 (6) ◽  
pp. 606-614 ◽  
Author(s):  
C. E. Chapman ◽  
W. J. Michalski ◽  
J. J. Séguin
Keyword(s):  
Muscle Spindle ◽  
Stretch Reflex ◽  
Synergistic Effects ◽  
Medial Gastrocnemius ◽  
Monosynaptic Reflex ◽  
Lateral Gastrocnemius ◽  
Stretch Reflexes ◽  
Decerebrate Cat ◽  
Muscle Cooling ◽  
Decerebrate Cats

The effects of muscle spindle secondary ending activity on the stretch reflex were studied in unanesthetized decerebrate cats. Activation of secondary endings was accomplished by reducing the muscle temperature. This has been shown to cause a sustained asynchronous discharge from secondary endings. Cooling of the medial gastrocnemius or lateral gastrocnemius–soleus muscles caused an increase in the phasic and tonic components of their stretch reflexes. Cooling of the relaxed medial gastrocnemius muscle caused similar increases in the components of the stretch reflex of the synergistic lateral gastrocnemius–soleus muscle and an increase in its monosynaptic reflex. It was concluded that the facilitatory autogenetic and synergistic effects of muscle cooling on the stretch and monosynaptic reflexes were brought about by activity in group II afferents from muscle spindle secondary endings and could not be ascribed to any other type of muscle receptor. These results support the concept of an excitatory role for the secondary endings of the muscle spindle in the stretch reflex of the decerebrate cat.

Effects of postural threat on spinal stretch reflexes: evidence for increased muscle spindle sensitivity?

2013 ◽  
Vol 110 (4) ◽  
pp. 899-906 ◽  
Author(s):  
Brian C. Horslen ◽  
Chantelle D. Murnaghan ◽  
J. Timothy Inglis ◽  
Romeo Chua ◽  
Mark G. Carpenter
Keyword(s):  
Muscle Spindle ◽  
Stretch Reflex ◽  
Sensory Information ◽  
Muscle Spindles ◽  
Support Surface ◽  
Stretch Reflexes ◽  
Postural Threat ◽  
Elevated Surface ◽  
Spinal Stretch Reflex ◽  
T Reflex

Standing balance is often threatened in everyday life. These threats typically involve scenarios in which either the likelihood or the consequence of falling is higher than normal. When cats are placed in these scenarios they respond by increasing the sensitivity of muscle spindles imbedded in the leg muscles, presumably to increase balance-relevant afferent information available to the nervous system. At present, it is unknown whether humans also respond to such postural threats by altering muscle spindle sensitivity. Here we present two studies that probed the effects of postural threat on spinal stretch reflexes. In study 1 we manipulated the threat associated with an increased consequence of a fall by having subjects stand at the edge of an elevated surface (3.2 m). In study 2 we manipulated the threat by increasing the likelihood of a fall by occasionally tilting the support surface on which subjects stood. In both scenarios we used Hoffmann (H) and tendon stretch (T) reflexes to probe the spinal stretch reflex circuit of the soleus muscle. We observed increased T-reflex amplitudes and unchanged H-reflex amplitudes in both threat scenarios. These results suggest that the synaptic state of the spinal stretch reflex is unaffected by postural threat and that therefore the muscle spindles activated in the T-reflexes must be more sensitive in the threatening conditions. We propose that this increase in sensitivity may function to satisfy the conflicting needs to restrict movement with threat, while maintaining a certain amount of sensory information related to postural control.

Statistical Considerations When Assessing Short Latency Stretch Reflexes in the Human Soleus Muscle

Motor Control ◽  
2015 ◽  
Vol 19 (4) ◽  
pp. 253-270 ◽  
Author(s):  
Asger Roer Pedersen ◽  
Peter William Stubbs ◽  
Jørgen Feldbæk Nielsen
Keyword(s):  
Ankle Joint ◽  
Soleus Muscle ◽  
Stretch Reflex ◽  
Short Latency ◽  
Response Magnitude ◽  
Variance Heterogeneity ◽  
Stretch Reflexes ◽  
Response Characteristics ◽  
Normally Distributed

The aim was to investigate trial-by-trial response characteristics in the short-latency stretch reflex (SSR). Fourteen dorsiflexion stretches were applied to the ankle joint with a precontracted soleus muscle on 2 days. The magnitude and variability of trial-by-trial responses of the SSR were assessed. The SSR was log-normally distributed and variance heterogeneous between subjects. For some subjects, the magnitude and variance differed between days and stretches. As velocity increased, variance heterogeneity tended to decrease and response magnitude increased. The current study demonstrates the need to assess trial-by-trial response characteristics and not averaged curves. Moreover, it provides an analysis of SSR characteristics accounting for log-normally distributed and variance heterogeneous trial-by-trial responses.

Regulation of the γ-Muscle Spindle System by Chemosensitive Muscle Afferents

1995 ◽  
pp. 174-176
Author(s):  
Mats Djupsjöbacka ◽  
Håkan Johansson ◽  
Mikael Bergenheim ◽  
Per Sjölander
Keyword(s):  
Muscle Spindle ◽  
Muscle Afferents ◽  
Spindle System

Evidence that low-threshold muscle afferents evoke long-latency stretch reflexes in human hand muscles

1991 ◽  
Vol 65 (5) ◽  
pp. 1089-1097 ◽  
Author(s):  
J. Noth ◽  
M. Schwarz ◽  
K. Podoll ◽  
F. Motamedi
Keyword(s):  
Index Finger ◽  
Angular Displacement ◽  
Metacarpophalangeal Joint ◽  
Muscle Afferents ◽  
Human Hand ◽  
Hand Muscles ◽  
Long Latency ◽  
M2 Response ◽  
Spinal Afferents ◽  
Wrist Flexors

1. The aim of the present study was to identify the type of spinal afferents involved in the generation of the long-latency response in intrinsic human hand muscles. Position-controlled extensions were imposed on the index finger or on the wrist of healthy subjects who were exerting a steady voluntary flexion force at the relevant joint. Averaged surface electromyographic (EMG) responses of the first dorsal interosseus muscle (FDI) or of the wrist flexors were evaluated with respect to latency and size. 2. Small transient angular displacements of the index finger (1 degree, as measured at the metacarpophalangeal joint), which are supposed to excite primary rather than secondary afferents, evoked two clearly discernible EMG responses with mean latencies of 32.3 ms (M1 response) and 54.7 ms (M2 response), respectively. The size of the M2 response exceeded the size of the M1 response by 60%. In the wrist flexors, transient stretch (1 degree) gave rise to a large M1 response (latency 22.8 ms) and a small, inconstent M2 response. 3. Small-amplitude vibration of the index finger elicited EMG responses in the FDI that were qualitatively and quantitatively similar to those seen in response to small transient stretches of the index finger. This was also true for fast ramp-and-hold stretches (stretch velocity 400 degrees/s, amplitude 5 degrees), whereas slow ramp-and-hold stretches (125 degrees/s, 5 degrees) elicited predominantly M2 responses. 4. In the FDI, the mechanical threshold of the M1 and M2 response to the transient angular displacement was approximately 0.15 degrees, with a tendency for the M2 response to appear at a lower threshold.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Motor learning and transfer: from feedback to feedforward control

2019 ◽  
Author(s):  
Rodrigo S. Maeda ◽  
Paul L. Gribble ◽  
J. Andrew Pruszynski
Keyword(s):  
Motor Learning ◽  
Muscle Activity ◽  
Shoulder Joint ◽  
Stretch Reflex ◽  
Feedforward Control ◽  
Motor Task ◽  
Joint Torques ◽  
Motor Commands ◽  
Shoulder Muscle ◽  
Long Latency

AbstractPrevious work has demonstrated that when learning a new motor task, the nervous system modifies feedforward (ie. voluntary) motor commands and that such learning transfers to fast feedback (ie. reflex) responses evoked by mechanical perturbations. Here we show the inverse, that learning new feedback responses transfers to feedforward motor commands. Sixty human participants (34 females) used a robotic exoskeleton and either 1) received short duration mechanical perturbations (20 ms) that created pure elbow rotation or 2) generated self-initiated pure elbow rotations. They did so with the shoulder joint free to rotate (normal arm dynamics) or locked (altered arm dynamics) by the robotic manipulandum. With the shoulder unlocked, the perturbation evoked clear shoulder muscle activity in the long-latency stretch reflex epoch (50-100ms post-perturbation), as required for countering the imposed joint torques, but little muscle activity thereafter in the so-called voluntary response. After locking the shoulder joint, which alters the required joint torques to counter pure elbow rotation, we found a reliable reduction in the long-latency stretch reflex over many trials. This reduction transferred to feedforward control as we observed 1) a reduction in shoulder muscle activity during self-initiated pure elbow rotation trials and 2) kinematic errors (ie. aftereffects) in the direction predicted when failing to compensate for normal arm dynamics, even though participants never practiced self-initiated movements with the shoulder locked. Taken together, our work shows that transfer between feedforward and feedback control is bidirectional, furthering the notion that these processes share common neural circuits that underlie motor learning and transfer.

QUANTIFIED DEEP TENDON REFLEX DEVICE, SECOND GENERATION

2008 ◽  
Vol 08 (01) ◽  
pp. 75-85 ◽  
Author(s):  
ROBERT LEMOYNE ◽  
FOAD DABIRI ◽  
ROOZBEH JAFARI
Keyword(s):  
Traumatic Brain Injury ◽  
Brain Injury ◽  
Stretch Reflex ◽  
Evaluation System ◽  
Deep Tendon Reflex ◽  
Reflex Response ◽  
Fundamental Aspect ◽  
Maximum Acceleration ◽  
Mems Accelerometer ◽  
Tendon Reflex

The deep tendon reflex is a fundamental aspect of neurological examinations. The severity of and degree of recovery from a traumatic brain injury can be assessed by the myotatic stretch reflex. A hyperactive reflex response is correlated with spasticity, which can also be correlated with the degree of damage to the supraspinal input, in essence assessing the severity of traumatic brain injury. The myotatic stretch reflex is clinically evaluated by the National Institute of Neurological Disorders and Stroke (NINDS) reflex scale (0–4); however, this scale lacks temporal data and may also vary in interpretation. The solution is a fully quantified evaluation system of the myotatic stretch reflex, whereby a patellar hammer's force input is based on original potential energy and a microelectromechanical system (MEMS) accelerometer quantifies the output. The MEMS accelerometer is attached to a set anchor point near the ankle. The reflex amplitude is based on the maximum acceleration of the reflex response. The quantified data collected from MEMS accelerometers are transmitted by a portable computer (i.e. a Pocket PC). This paper describes a device that quantitatively evaluates the reflex response using accelerometers and that demonstrates precision for reproducibility.

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