Modification of Motor Output to Compensate for Unanticipated Load Conditions During Rapid Voluntary Movements

Lee, R.G.; Lucier, Gregory E.; Mustard, B.E.; White, David G.

doi:10.1017/s0317167100035988

Cited by 56 publications

(5 citation statements)

References 21 publications

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“…Wrist flexion movements were characterized by typical triphasic EMG patterns, shown for single non-loaded and loaded movements from experiment 2 in Figs. 4A and 4B, respectively (see also Lee et al 1986). Both phasic and tonic flexor EMG signals increased when the load opposed the movement (Fig.…”

Section: Resultsmentioning

confidence: 76%

Control variables and proprioceptive feedback in fast single-joint movement

Levin

Lamarre²,

Feldman³

1995

Can. J. Physiol. Pharmacol.

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Sensorimotor mechanisms were studied on the basis of kinematic and electromyographic data as well as the static torque developed by the muscles as a function of joint angle. The latter relationship is known as the torque/angle characteristic. Fast single-joint movement may result from a shift in this characteristic and a change in its slope. Such movements were studied at the wrist in 9 normal and 1 deafferented subject. After training to flex the wrist to a target, subjects repeated the same movements but in random test trials movements were opposed by the load generated by linear position feedback to a torque motor. At the end of the loaded trials, the load was suddenly removed. In the second experiment, subjects made wrist movements to the target that were opposed by the load and, on random test trials, the movements were not loaded. In these test trials, the wrist arrived in a static position outside the target zone. In both experiments, subjects were instructed not to correct errors. The final torque/angle characteristics specified in the movements were reconstructed on the basis of the static wrist positions and torques before and after unloading. Normal subjects made movements by shifting the position of the torque/angle characteristic and by increasing its slope. If subjects indeed maintained the same pattern of control variables (descending commands), the same final position of the characteristic would be reproduced from trial to trial regardless of load perturbations. This assumption of equifinality was tested by comparing the final position of the wrist in nonloaded movements with that after removal of the load in loaded movements. Equifinality was observed in normal subjects. Movements in the deafferented subject were also associated with a shift of the torque/angle characteristic and a change in its slope. However, she was unable to consistently reproduce its final position. In spite of muscle coactivation, her maximal stiffness was lower than in normal subjects. In the absence of vision, the subject made movements with the load by increasing the slope of the characteristic instead of by shifting its position far enough. Load perturbation affected her final wrist position (inequifinality), which may reflect the presence of a significant hysteresis of the characteristic as a result of the absence of stretch reflexes. The deficits following deafferentation presumably result from the destruction of biomechanical and sensorimotor mechanisms including the ability of control variables to specify the positional frame of reference for afferent and descending systems.

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Section: Resultsmentioning

confidence: 76%

Control variables and proprioceptive feedback in fast single-joint movement

Levin

Lamarre²,

Feldman³

1995

Can. J. Physiol. Pharmacol.

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“…1987: Jung, 1979 and ballistic movements (Lee, Lucier, Mustard, & White, 1986). This comnion neural mechanism is probably spinal in origin because the effect of height on a spinal pathway is minimal as compared to a transcortical pathway.…”

Section: Discxssiotimentioning

confidence: 98%

The Relationship Between Body Height Extremes and the Conditioned Patellar Tendon Reflex Response

Burke

Koceja

Kamen

1993

International Journal of Neuroscience

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The purpose of this study was to determine the effects of extreme body heights on the conditioned patellar tendon reflex response in an attempt to differentiate between the contributions of supraspinal and spinal mechanisms on long-latency reflex facilitation. Unilateral and conditioned right patellar tendon reflexes were assessed in 10 extremely short males and females and 10 extremely tall males and females. The conditioning stimulus was a contralateral patellar tendon tap and the conditioning intervals were 10, 15, 25, 50, 60, 75, 100, 150, and 300 ms. There was a long-latency facilitation of quadriceps excitability beginning at the 75 ms conditioning interval regardless of the height of the subject. It is hypothesized that the similar conditioned patellar tendon recovery profiles in the extremely short subjects and the extremely tall subjects reflects the activation of a spinal polysynaptic pathway as the predominant mechanism for our long-latency reflex facilitation.

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“…When perturbations were applied at or after the beginning of the movement, the EMG responses were observed at latencies ranging from 25 to Ͼ100 ms from the time that the limb started moving or the load was changed. Based on the latency of the EMG responses, it was concluded that the segmental reflexes were active during movement (Bennett 1993;Latash 1994;Lee et al 1986;Sanes 1986;Smeets et al 1990), were not active during movement (Day and Marsden 1982;Wadman et al 1979), or were initially suppressed and facilitated later during movement (Gottlieb 1996). The EMG responses were attributed to long-latency reflexes (Day and Marsden 1982) or to short-latency segmental reflexes.…”

Section: Introductionmentioning

confidence: 99%

“…The published results do not lend themselves to a straightforward comparison. The experimental protocols included torque pulse perturbations (Cooke 1980), unexpected changes in bias torque (Lee et al 1986;Marsden et al 1976b), movement arrest or release (Hallett and Marsden 1979;Ives et al 1993Ives et al , 1999Wadman et al 1979), constant position error (Bennett 1993), or changes in the load inertia or viscosity (Day and Marsden 1982;Gottlieb 1996;Latash 1994;Sanes 1986;Smeets et al 1990). In some of the studies, the onset of the EMG responses was given with respect to the agonist EMG onset.…”

Section: Introductionmentioning

confidence: 99%

“…To compare the published results, it is necessary to account for at least a 20-ms delay between the agonist EMG onset and detectable movement onset (Corcos et al 1992). In addition, in some of the experiments the movement onset was further delayed because the limb started moving only after the joint torque exceeded a threshold (Hallett et al 1975;Lee et al 1986;Marsden et al 1976a;Smeets et al 1990). Once the delay between the agonist EMG onset and change in movement kinematics onset is taken into account, it can be concluded that in all of the experiments described in the preceding text, the EMG responses were never observed earlier than ϳ100 -200 ms after the agonist EMG onset.…”

Section: Introductionmentioning

confidence: 99%

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EMG Responses to an Unexpected Load in Fast Movements Are Delayed With an Increase in the Expected Movement Time

Shapiro

Gottlieb

Corcos

2004

Journal of Neurophysiology

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When moving an object, the motor system estimates the dynamic properties of the object and then controls the movement using a combination of predictive feedforward control and proprioceptive feedback. In this study, we examined how the feedforward and proprioceptive feedback processes depend on the expected movement task. Subjects made fast elbow flexion movements from an initial position to a target. The experimental protocol included movements made over a short and a long distance against an expected light or heavy inertial load. In each task in a few randomly chosen trials, a motor applied an unexpected viscous load that produced a velocity error, defined as the difference between the expected and unexpected velocities, and electromyographic (EMG) responses. The EMG responses appeared not earlier than 170-250 ms from the agonist EMG onset. Our main finding is that the onset of the EMG responses was correlated with the expected time of peak velocity, which increased for longer distances and larger loads. An analysis of the latency of the EMG responses with respect to the velocity error suggested that the EMG responses were due to segmental reflexes. We conclude that segmental reflex gains are centrally modulated with the time course dependent on the expected movement task. According to this view, the control of fast point-to-point movement is feedforward from the agonist EMG onset until the expected time of peak velocity after which the segmental reflex feedback is briefly facilitated.

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Modification of Motor Output to Compensate for Unanticipated Load Conditions During Rapid Voluntary Movements

Cited by 56 publications

References 21 publications

Control variables and proprioceptive feedback in fast single-joint movement

Control variables and proprioceptive feedback in fast single-joint movement

The Relationship Between Body Height Extremes and the Conditioned Patellar Tendon Reflex Response

EMG Responses to an Unexpected Load in Fast Movements Are Delayed With an Increase in the Expected Movement Time

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