A re-examination of the effects of instruction on the long-latency stretch reflex response of the flexor pollicis longus muscle

1994 ◽  
Vol 100 (3) ◽  
pp. 515-521 ◽  
Author(s):  
Charles Capaday ◽  
Robert Forget ◽  
Ted Milner
Keyword(s):  
Stretch Reflex ◽  
Reflex Response ◽  
Flexor Pollicis Longus ◽  
Long Latency ◽  
Longus Muscle

scholarly journals Different mechanisms underlie the long-latency stretch reflex response of active human muscle at different joints.

1991 ◽  
Vol 444 (1) ◽  
pp. 631-643 ◽  
Author(s):  
A F Thilmann ◽  
M Schwarz ◽  
R Töpper ◽  
S J Fellows ◽  
J Noth
Keyword(s):  
Stretch Reflex ◽  
Human Muscle ◽  
Reflex Response ◽  
Long Latency

Voluntary and reflexive recruitment of flexor carpi radialis motor units in humans

1985 ◽  
Vol 53 (5) ◽  
pp. 1194-1200 ◽  
Author(s):  
B. Calancie ◽  
P. Bawa
Keyword(s):  
Motor Unit ◽  
Stretch Reflex ◽  
Latency Period ◽  
Motor Units ◽  
Short Latency ◽  
Reflex Response ◽  
Recruitment Threshold ◽  
Flexor Carpi Radialis ◽  
Single Motor Units ◽  
Long Latency

The order of recruitment of flexor carpi radialis (FCR) motor units was studied during voluntary and reflexive activation of the motoneuron pool for two adult subjects. During slow "voluntary" activation, the recruitment threshold for tonic motoneuron firing was determined, and then the twitch profile of the motor unit was computed by the spike-triggered averaging technique. A positive correlation (r = 0.79 and 0.68 for the two subjects, respectively) between recruitment threshold and twitch amplitude implies that recruitment of FCR motoneurons during slow ramp isometric contractions proceeds in order of increasing size. The accompanying paper describes the behavior of single motor units during the short- and long-latency periods of the stretch reflex. When the effects of sufficient voluntary facilitation (preload) combined with a sufficiently large torque step were just adequate to cause a motor unit to fire during the stretch reflex, its response was virtually always confined to the long-latency period. In addition, the first unit to begin responding to muscle stretch always had the lowest voluntary recruitment threshold relative to other units "visible" at that recording site. By making this unit tonic, the reflex response to the same load increased substantially during the short-latency reflex period, while a second unit increased its reflex response probability during the long-latency period. Thus the voluntary recruitment order of two or more motor units is preserved during the stretch reflex, and is in fact maintained within first the long-latency and then short-latency components of this reflex.

Reflex Responses Induced by Tooth Unloading

2000 ◽  
Vol 84 (2) ◽  
pp. 1088-1092 ◽  
Author(s):  
Kemal S. Türker ◽  
Melissa Jenkins
Keyword(s):  
Local Anesthetic ◽  
Muscle Activity ◽  
Masseter Muscle ◽  
Horizontal Direction ◽  
Reflex Response ◽  
Maxillary Incisor ◽  
Static Force ◽  
Incisor Tooth ◽  
Long Latency ◽  
Unloading Reflex

The reflex response of the masseter muscle to the rapid unloading of a single maxillary incisor tooth was studied. Unloading of a static force of 2 N in the horizontal direction resulted in a short-latency excitation, inhibition, and long-latency excitation of masseter muscle activity occurring at latencies of approximately 13, 20, and 40 ms, respectively, with a corresponding change in bite force occurring slightly later in each case. Following the blocking of periodontal input by the injection of local anesthetic around the stimulated tooth, inhibitory responses were abolished. Therefore, it is concluded that the observed masseteric inhibition was caused by the unloading of periodontal mechanoreceptors and thus that these receptors may contribute to the jaw unloading reflex.

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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