LONG-LATENCY INTRACORTICAL INHIBITION DURING UNILATERAL MUSCLE ACTIVITY

2017 ◽  
pp. 333-338
Author(s):  
Kapka Mancheva ◽  
Diana I. Stephanova ◽  
Werner Wolf ◽  
Andon Kossev
Keyword(s):  
Muscle Activity ◽  
Intracortical Inhibition ◽  
Long Latency

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.

Effects of water immersion on short- and long-latency afferent inhibition, short-interval intracortical inhibition, and intracortical facilitation

2013 ◽  
Vol 124 (9) ◽  
pp. 1846-1852 ◽  
Author(s):  
Daisuke Sato ◽  
Koya Yamashiro ◽  
Takuya Yoshida ◽  
Hideaki Onishi ◽  
Yoshimitsu Shimoyama ◽  
...  
Keyword(s):  
Water Immersion ◽  
Short Interval ◽  
Intracortical Inhibition ◽  
Intracortical Facilitation ◽  
Afferent Inhibition ◽  
Long Latency

Influence of the behavioral goal and environmental obstacles on rapid feedback responses

2012 ◽  
Vol 108 (4) ◽  
pp. 999-1009 ◽  
Author(s):  
Joseph Y. Nashed ◽  
Frédéric Crevecoeur ◽  
Stephen H. Scott
Keyword(s):  
Muscle Activity ◽  
Motor System ◽  
Optimal Feedback Control ◽  
Motor Responses ◽  
Spatial Properties ◽  
Long Latency ◽  
Circular Target ◽  
Motor Actions ◽  
Behavioral Goal ◽  
Feedback Responses

The motor system must consider a variety of environmental factors when executing voluntary motor actions, such as the shape of the goal or the possible presence of intervening obstacles. It remains unknown whether rapid feedback responses to mechanical perturbations also consider these factors. Our first experiment quantified how feedback corrections were altered by target shape, which was either a circular dot or a bar. Unperturbed movements to each target were qualitatively similar on average but with greater dispersion of end point positions when reaching to the bar. On random trials, multijoint torque perturbations deviated the hand left or right. When reaching to a circular target, perturbations elicited corrective movements that were directed straight to the location of the target. In contrast, corrective movements when reaching to a bar were redirected to other locations along the bar axis. Our second experiment quantified whether the presence of obstacles could interfere with feedback corrections. We found that hand trajectories after the perturbations were altered to avoid obstacles in the environment. Importantly, changes in muscle activity reflecting the different target shapes (bar vs. dot) or the presence of obstacles were observed in as little as 70 ms. Such changes in motor responses were qualitatively consistent with simulations based on optimal feedback control. Taken together, these results highlight that long-latency motor responses consider spatial properties of the goal and environment.

Long-latency, inhibitory spinal pathway to ankle flexors activated by homonymous group 1 afferents

2014 ◽  
Vol 111 (12) ◽  
pp. 2544-2553 ◽  
Author(s):  
Ephrem T. Zewdie ◽  
Francois D. Roy ◽  
Yoshino Okuma ◽  
Jaynie F. Yang ◽  
Monica A. Gorassini
Keyword(s):  
Muscle Activity ◽  
Corticospinal Tract ◽  
Inhibitory Pathway ◽  
Thoracic Spinal Cord ◽  
Thoracic Spinal ◽  
Long Latency ◽  
Inhibitory Feedback ◽  
Spinal Pathway ◽  
Low Threshold ◽  
Pulse Stimulation

Inhibitory feedback from sensory pathways is important for controlling movement. Here, we characterize, for the first time, a long-latency, inhibitory spinal pathway to ankle flexors that is activated by low-threshold homonymous afferents. To examine this inhibitory pathway in uninjured, healthy participants, we suppressed motor-evoked potentials (MEPs), produced in the tibialis anterior (TA), by a prior stimulation to the homonymous common peroneal nerve (CPN). The TA MEP was suppressed by a triple-pulse stimulation to the CPN, applied 40, 50, and 60 ms earlier and at intensities of 0.5–0.7 times motor threshold (average suppression of test MEP was 33%). Whereas the triple-pulse stimulation was below M-wave and H-reflex threshold, it produced a long-latency inhibition of background muscle activity, approximately 65–115 ms after the CPN stimulation, a time period that overlapped with the test MEP. However, not all of the MEP suppression could be accounted for by this decrease in background muscle activity. Evoked responses from direct activation of the corticospinal tract, at the level of the brain stem or thoracic spinal cord, were also suppressed by low-threshold CPN stimulation. Our findings suggest that low-threshold muscle and cutaneous afferents from the CPN activate a long-latency, homonymous spinal inhibitory pathway to TA motoneurons. We propose that inhibitory feedback from spinal networks, activated by low-threshold homonymous afferents, helps regulate the activation of flexor motoneurons by the corticospinal tract.

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.

scholarly journals Temporal Evolution of “Automatic Gain-Scaling”

2009 ◽  
Vol 102 (2) ◽  
pp. 992-1003 ◽  
Author(s):  
J. Andrew Pruszynski ◽  
Isaac Kurtzer ◽  
Timothy P. Lillicrap ◽  
Stephen H. Scott
Keyword(s):  
Steady State ◽  
Muscle Activity ◽  
Temporal Evolution ◽  
Rapid Decrease ◽  
Short Latency ◽  
State Activity ◽  
Long Latency ◽  
Short Latency Response ◽  
Latency Response ◽  
Steady State Activity

The earliest neural response to a mechanical perturbation, the short-latency stretch response (R1: 20–45 ms), is known to exhibit “automatic gain-scaling” whereby its magnitude is proportional to preperturbation muscle activity. Because gain-scaling likely reflects an intrinsic property of the motoneuron pool (via the size-recruitment principle), counteracting this property poses a fundamental challenge for the nervous system, which must ultimately counter the absolute change in load regardless of the initial muscle activity (i.e., show no gain-scaling). Here we explore the temporal evolution of gain-scaling in a simple behavioral task where subjects stabilize their arm against different background loads and randomly occurring torque perturbations. We quantified gain-scaling in four elbow muscles (brachioradialis, biceps long, triceps lateral, triceps long) over the entire sequence of muscle activity following perturbation onset—the short-latency response, long-latency response (R2: 50–75 ms; R3: 75–105 ms), early voluntary corrections (120–180 ms), and steady-state activity (750–1250 ms). In agreement with previous observations, we found that the short-latency response demonstrated substantial gain-scaling with a threefold increase in background load resulting in an approximately twofold increase in muscle activity for the same perturbation. Following the short-latency response, we found a rapid decrease in gain-scaling starting in the long-latency epoch (∼75-ms postperturbation) such that no significant gain-scaling was observed for the early voluntary corrections or steady-state activity. The rapid decrease in gain-scaling supports our recent suggestion that long-latency responses and voluntary control are inherently linked as part of an evolving sensorimotor control process through similar neural circuitry.

scholarly journals Coordinating long-latency stretch responses across the shoulder, elbow, and wrist during goal-directed reaching

2016 ◽  
Vol 116 (5) ◽  
pp. 2236-2249 ◽  
Author(s):  
Jeffrey Weiler ◽  
James Saravanamuttu ◽  
Paul L. Gribble ◽  
J. Andrew Pruszynski
Keyword(s):  
Simple Form ◽  
Muscle Activity ◽  
Kinematic Redundancy ◽  
Mechanical Perturbation ◽  
Intersegmental Dynamics ◽  
Long Latency ◽  
Voluntary Behavior ◽  
Visual Targets ◽  
Perturbation Magnitude ◽  
Stretch Response

The long-latency stretch response (muscle activity 50–100 ms after a mechanical perturbation) can be coordinated across multiple joints to support goal-directed actions. Here we assessed the flexibility of such coordination and whether it serves to counteract intersegmental dynamics and exploit kinematic redundancy. In three experiments, participants made planar reaches to visual targets after elbow perturbations and we assessed the coordination of long-latency stretch responses across shoulder, elbow, and wrist muscles. Importantly, targets were placed such that elbow and wrist (but not shoulder) rotations could help transport the hand to the target—a simple form of kinematic redundancy. In experiment 1 we applied perturbations of different magnitudes to the elbow and found that long-latency stretch responses in shoulder, elbow, and wrist muscles scaled with perturbation magnitude. In experiment 2 we examined the trial-by-trial relationship between long-latency stretch responses at adjacent joints and found that the magnitudes of the responses in shoulder and elbow muscles, as well as elbow and wrist muscles, were positively correlated. In experiment 3 we explicitly instructed participants how to use their wrist to move their hand to the target after the perturbation. We found that long-latency stretch responses in wrist muscles were not sensitive to our instructions, despite the fact that participants incorporated these instructions into their voluntary behavior. Taken together, our results indicate that, during reaching, the coordination of long-latency stretch responses across multiple joints counteracts intersegmental dynamics but may not be able to exploit kinematic redundancy.

Task-dependent changes of motor cortical network excitability during precision grip compared to isolated finger contraction

2012 ◽  
Vol 107 (5) ◽  
pp. 1522-1529 ◽  
Author(s):  
Nezha Kouchtir-Devanne ◽  
Charles Capaday ◽  
François Cassim ◽  
Philippe Derambure ◽  
Hervé Devanne
Keyword(s):  
Stimulus Intensity ◽  
Motor Evoked Potentials ◽  
Precision Grip ◽  
Silent Period ◽  
Intracortical Inhibition ◽  
Emg Activity ◽  
Maximum Slope ◽  
Corticospinal Pathway ◽  
Long Latency ◽  
Motor Cortical

The purpose of this study was to determine whether task-dependent differences in corticospinal pathway excitability occur in going from isolated contractions of the index finger to its coordinated activity with the thumb. Focal transcranial magnetic stimulation (TMS) was used to measure input-output (I/O) curves—a measure of corticospinal pathway excitability—of the contralateral first dorsal interosseus (FDI) muscle in 21 healthy subjects performing two isometric motor tasks: index abduction and precision grip. The level of FDI electromyographic (EMG) activity was kept constant across tasks. The amplitude of the FDI motor evoked potentials (MEPs) and the duration of FDI silent period (SP) were plotted against TMS stimulus intensity and fitted, respectively, to a Boltzmann sigmoidal function. The plateau level of the FDI MEP amplitude I/O curve increased by an average of 40% during the precision grip compared with index abduction. Likewise, the steepness of the curve, as measured by the value of the maximum slope, increased by nearly 70%. By contrast, all I/O curve parameters [plateau, stimulus intensity required to obtain 50% of maximum response ( S50), and slope] of SP duration were similar between the two tasks. Short- and long-latency intracortical inhibitions (SICI and LICI, respectively) were also measured in each task. Both measures of inhibition decreased during precision grip compared with the isolated contraction. The results demonstrate that the motor cortical circuits controlling index and thumb muscles become functionally coupled when the muscles are used synergistically and this may be due, at least in part, to a decrease of intracortical inhibition and an increase of recurrent excitation.

scholarly journals Goal-dependent modulation of the long-latency stretch response at the shoulder, elbow, and wrist

2015 ◽  
Vol 114 (6) ◽  
pp. 3242-3254 ◽  
Author(s):  
Jeffrey Weiler ◽  
Paul L. Gribble ◽  
J. Andrew Pruszynski
Keyword(s):  
Muscle Activity ◽  
Visual Target ◽  
Relative Magnitude ◽  
Kinematic Redundancy ◽  
Mechanical Perturbation ◽  
Intersegmental Dynamics ◽  
Shoulder Muscles ◽  
Long Latency ◽  
Dependent Activity ◽  
Stretch Response

Many studies have demonstrated that muscle activity 50–100 ms after a mechanical perturbation (i.e., the long-latency stretch response) can be modulated in a manner that reflects voluntary motor control. These previous studies typically assessed modulation of the long-latency stretch response from individual muscles rather than how this response is concurrently modulated across multiple muscles. Here we investigated such concurrent modulation by having participants execute goal-directed reaches to visual targets after mechanical perturbations of the shoulder, elbow, or wrist while measuring activity from six muscles that articulate these joints. We found that shoulder, elbow, and wrist muscles displayed goal-dependent modulation of the long-latency stretch response, that the relative magnitude of participants' goal-dependent activity was similar across muscles, that the temporal onset of goal-dependent muscle activity was not reliably different across the three joints, and that shoulder muscles displayed goal-dependent activity appropriate for counteracting intersegmental dynamics. We also observed that the long-latency stretch response of wrist muscles displayed goal-dependent modulation after elbow perturbations and that the long-latency stretch response of elbow muscles displayed goal-dependent modulation after wrist perturbations. This pattern likely arises because motion at either joint could bring the hand to the visual target and suggests that the nervous system rapidly exploits such simple kinematic redundancy when processing sensory feedback to support goal-directed actions.

Context-dependent inhibition of unloaded muscles during the long-latency epoch

2015 ◽  
Vol 113 (1) ◽  
pp. 192-202 ◽  
Author(s):  
Joseph Y. Nashed ◽  
Isaac L. Kurtzer ◽  
Stephen H. Scott
Keyword(s):  
Inhibitory Activity ◽  
Muscle Activity ◽  
Inhibitory Response ◽  
Short Latency ◽  
Peripheral Target ◽  
Intersegmental Dynamics ◽  
Long Latency ◽  
Dependent Inhibition ◽  
Elbow Motion ◽  
Different Levels

A number of studies have highlighted the sophistication of corrective responses in lengthened muscles during the long-latency epoch. However, in various contexts, unloading can occur, which requires corrective actions from a shortened muscle. Here, we investigate the sophistication of inhibitory responses in shortened muscles due to unloading. Our first experiment quantified the inhibitory responses following an unloading torque that displaced the hand either into or away from a peripheral target. We observed larger long-latency inhibitory responses when perturbed into the peripheral target compared with away from the target. In our second experiment, we characterized the degree of inhibition following unloading with respect to different levels of preperturbation muscle activity. We initially observed that the inhibitory activity during the short-latency epoch scaled with increased levels of preperturbation muscle activity. However, this scaling peaked early in the R2 epoch (∼50 ms) but then quickly diminished through the rest of the long-latency epoch. Finally, in experiment 3, we investigated whether inhibitory perturbation responses consider intersegmental dynamics of the limb. We quantified unloading responses for either pure shoulder or pure elbow torques that evoked similar motion at the shoulder but different elbow motion. The long-latency inhibitory response in the shoulder, unlike the short-latency, was greater for the shoulder torque compared with the response following an elbow torque, as previously observed for a loading response. Taken together, these results illustrate that the long-latency unloading response is capable of a similar level of complexity as observed when loads are applied to the limb.

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