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.

scholarly journals Task-dependent coordination of rapid bimanual motor responses

2012 ◽  
Vol 107 (3) ◽  
pp. 890-901 ◽  
Author(s):  
Michael Dimitriou ◽  
David W. Franklin ◽  
Daniel M. Wolpert
Keyword(s):  
Sensory Information ◽  
Optimal Feedback Control ◽  
Single Trial ◽  
Mechanical Perturbation ◽  
Contralateral Limb ◽  
Motor Responses ◽  
Bimanual Task ◽  
Rapid Responses ◽  
Long Latency ◽  
Long Latency Reflex

Optimal feedback control postulates that feedback responses depend on the task relevance of any perturbations. We test this prediction in a bimanual task, conceptually similar to balancing a laden tray, in which each hand could be perturbed up or down. Single-limb mechanical perturbations produced long-latency reflex responses (“rapid motor responses”) in the contralateral limb of appropriate direction and magnitude to maintain the tray horizontal. During bimanual perturbations, rapid motor responses modulated appropriately depending on the extent to which perturbations affected tray orientation. Specifically, despite receiving the same mechanical perturbation causing muscle stretch, the strongest responses were produced when the contralateral arm was perturbed in the opposite direction (large tray tilt) rather than in the same direction or not perturbed at all. Rapid responses from shortening extensors depended on a nonlinear summation of the sensory information from the arms, with the response to a bimanual same-direction perturbation (orientation maintained) being less than the sum of the component unimanual perturbations (task relevant). We conclude that task-dependent tuning of reflexes can be modulated online within a single trial based on a complex interaction across the arms.

scholarly journals Trunk Angle Modulates Feedforward and Feedback Control during Single-Limb Squatting

2021 ◽  
Vol 6 (4) ◽  
pp. 82
Author(s):  
Kristin A. Johnson ◽  
Shojiro Nozu ◽  
Richard K. Shields
Keyword(s):  
Motor Control ◽  
Feedback Control ◽  
Muscle Activity ◽  
Feedforward Control ◽  
Cruciate Ligament ◽  
Dynamic Performance ◽  
Ligament Injury ◽  
Long Latency ◽  
Long Latency Reflexes ◽  
Feedback Responses

Trunk positioning and unexpected perturbations are high-risk conditions at the time of anterior cruciate ligament injury. The influence of trunk positioning on motor control responses to perturbation during dynamic performance is not known. We tested the influence of trunk position on feedforward and feedback control during unexpected perturbations while performing a novel single-limb squatting task. We also assessed the degree that feedforward control was predictive of feedback responses. In the flexed trunk condition, there were increased quadriceps (p < 0.026) and gluteus medius long-latency reflexes (p < 0.001) and greater quadriceps-to-hamstrings co-contraction during feedforward (p = 0.017) and feedback (p = 0.007) time bins. Soleus long-latency reflexes increased more than 100% from feedforward muscle activity regardless of trunk condition. Feedforward muscle activity differentially predicted long-latency reflex responses depending on the muscle (R2: 0.47–0.97). These findings support the concept that trunk positioning influences motor control responses to perturbation and that feedback responses may be invariant to the feedforward control strategy.

scholarly journals Fractionation of the visuomotor feedback response to directions of movement and perturbation

2014 ◽  
Vol 112 (9) ◽  
pp. 2218-2233 ◽  
Author(s):  
David W. Franklin ◽  
Sae Franklin ◽  
Daniel M. Wolpert
Keyword(s):  
The Body ◽  
Reaching Movements ◽  
Optimal Feedback Control ◽  
Statistical Distributions ◽  
Motor Responses ◽  
The World ◽  
Limb Posture ◽  
Task Irrelevant ◽  
And Control ◽  
Feedback Responses

Recent studies have highlighted the modulation and control of feedback gains as support for optimal feedback control. While many experiments contrast feedback gains across different environments, only a few have demonstrated the appropriate modulation of feedback gains from one movement to the next. Here we extend previous work by examining whether different visuomotor feedback gains can be learned for different directions of movement or perturbation directions in the same posture. To do this we measure visuomotor responses (involuntary motor responses to shifts in the visual feedback of the hand) during reaching movements. Previous work has demonstrated that these feedback responses can be modulated depending on the statistical distributions of the environment. Specifically, feedback gains were upregulated for task-relevant environments and downregulated for task-irrelevant environments. Using these two statistical distributions, the first experiment examined whether these feedback responses could be independently modulated for the same limb posture for two directions of movement (same limb posture but on either an inward or outward movement), while the second examined whether the feedback responses could modulate, within a single movement, to perturbations to the left or right of the reach. Both experiments demonstrated that visuomotor feedback responses could be learned independently such that the response was appropriate for the environment. This work demonstrates that feedback gains can be simultaneously tuned (upregulated and downregulated) depending on the state of the body and the environment. The results indicate the degree to which feedback responses can be fractionated in order to adapt to the world.

Observing painful events in others leads to a temporally extended general response facilitation in the self

2017 ◽  
Author(s):  
Carl Michael Orquiola Galang
Keyword(s):  
Motor System ◽  
Response Times ◽  
Motor Evoked Potentials ◽  
Painful Stimulus ◽  
Facilitation Effect ◽  
Motor Responses ◽  
Response Facilitation ◽  
Task Instructions ◽  
General Response ◽  
Muscle Specificity

Excitability in the motor cortex is modulated when we observe other people receiving a painful stimulus (Avenanti et al., 2005). However, the task dependency of this modulation is not well understood, as different paradigms have yielded seemingly different results. Previous neurophysiological work employing transcranial magnetic stimulation (TMS) suggests that watching another person’s hand being pierced by a needle leads to a muscle specific inhibition, assessed via motor evoked potentials. Results from previous behavioural studies suggest that overt behavioural responses are facilitated due to pain observation (Morrison et al., 2007a; 2007b). There are several paradigmatic differences both between typical TMS studies and behavioural studies, and within behavioural studies themselves, that limit our overall understanding of how pain observation affects the motor system. In the current study, we combine elements of typical TMS experimental designs in a behavioural assessment of how pain observation affects overt behavioural responding. Specifically, we examined the muscle specificity, timing, and direction of modulation of motor responses due to pain observation. To assess muscle specificity, we employed pain and non-pain videos from previous TMS studies in a Go/No-Go task in which participants responded by either pressing a key with their index finger or with their foot. To assess timing, we examined response times for Go signals presented at 0ms or 500ms after the video. Results indicate that observation of another individual receiving a painful stimulus leads to a non-effector specific, temporally extended response facilitation (e.g., finger and foot facilitation present at 0ms and 500ms delays), compared to observation of non-pain videos. This behavioural facilitation effect differs from the typical motor inhibition seen in TMS studies, and we argue that the effects of pain observation on the motor system are state-dependent, with different states induced via task instructions. We discuss our results in light of previous work on motor responses to pain observation.

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.

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.

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

scholarly journals Voluntary modification of rapid tactile-motor responses during reaching differs from its visuomotor counterpart

2020 ◽  
Vol 124 (1) ◽  
pp. 284-294
Author(s):  
Sasha Reschechtko ◽  
J. Andrew Pruszynski
Keyword(s):  
Muscle Activity ◽  
Visual Target ◽  
Incorrect Response ◽  
Tactile Feedback ◽  
Motor Responses ◽  
Correct Direction

When people reach toward a visual target that moves suddenly, they automatically correct their reach to follow the object; even when explicitly instructed not to follow a moving visual target, people exhibit an initial incorrect movement before moving in the correct direction. We show that when people use tactile feedback, they do not show an initial incorrect response, even though early muscle activity still occurs.

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