The effect of the amplitude of motor action on anticipatory postural adjustments

Aruin, Alexander S.; Shiratori, Takako

doi:10.1016/j.jelekin.2003.12.002

Cited by 20 publications

(17 citation statements)

References 26 publications

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“…In particular, the constancy of M max in the PRE and POST sessions revealed a substantial stability of the recording apparatus all along the 12-h period, as observed also by Facchini et al (2002) after 3 days of immobilization. Moreover, since movement amplitude and duration may affect the precision of the movement itself as well as the characteristics of APAs (Lee et al 1987;Aruin and Shiratori 2004), it has also been verified that the kinematics of index finger flexion did not change in the two experimental conditions. Last, the level of the background EMG activity in BB and AD was found to be analogous in the two sessions, the sensitivity of the pool to facilitation or to inhibition being thus comparable in the two situations (Crone et al 1990).…”

Section: Discussionmentioning

confidence: 85%

“…Since APAs are scaled to prime mover activation (Aruin and Shiratori 2004), a parallel change should then occur in APAs too, but this would lead to a significant increase of both excitatory APAs in TB and inhibitory APAs in BB. The unbalanced effect showed in the antagonistic muscles BB and TB suggests, in agreement with the results of Facchini et al (2002), that immobilization triggers a tonic enhancement of inhibitory drive involving not only the cortical representation of the immobilized joint but also the adjacent areas.…”

Section: Discussionmentioning

confidence: 99%

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Hand immobilization affects arm and shoulder postural control

et al. 2012

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It is a common experience, immediately after the removal of a cast or a splint, to feel motor awkwardness, which is usually attributed to muscular and joint immobilization. However, the same feeling may also be perceived after a brief period of immobilization. We provide evidence that this last effect stems from changes in the cortical organization of the focal movement as well as in the associated anticipatory postural adjustments. Indeed, these two aspects of the motor act are strongly correlated, although scaled in different manners. In fact, they are both shaped in the primary motor cortex, they both undergo similar amplitude and latency modulation and, as we will show, they are both impaired by the immobilization of the lone prime mover. Neuromuscular effects of limb immobilization are well known; however, most papers focus on changes occurring in the pathways projecting to the prime mover, which acts on the immobilized joint. Conversely, this study investigates the effect of immobilization on anticipatory postural adjustments. Indeed, we show that 12 h of wrist and fingers immobilization effectively modify anticipatory postural adjustments of the elbow and the shoulder, that is, those joints not immobilized within the fixation chain. Accordingly, the motor impairment observed after short-term immobilization most likely stems from the unbalance between anticipatory postural adjustments and the focal movement.

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Section: Discussionmentioning

confidence: 85%

Section: Discussionmentioning

confidence: 99%

Hand immobilization affects arm and shoulder postural control

et al. 2012

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“…All signals were sampled at 1000 Hz with 16-bit resolution. For details on the experiment protocol used to collect EMGs, refer to Aruin et al 1,2 …”

Section: Performance Evaluationmentioning

confidence: 99%

Teager–Kaiser Energy Operation of Surface EMG Improves Muscle Activity Onset Detection

2007

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This study presents a novel method for detection of the onset time of muscle activity using surface electromyogram (EMG) signals. The method takes advantage of the nonlinear properties of the Teager-Kaiser energy (TKE) operator, which simultaneously considers the amplitude and instantaneous frequency of the surface EMG, and therefore increases the prospects of muscle activity detection. To detect the onset time of muscle activity, the surface EMG signal was first processed by the TKE operator to highlight motor unit activities of the muscle. Then a robust threshold-based algorithm was developed in the TKE domain to locate the onset of muscle activity. The validity of the proposed method was illustrated using various surface EMG simulations as well as experimental surface EMG recordings.

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“…A load release task has been used in many APA studies (Aruin & Latash, 1996; Slijper et al 2002; Aruin & Shiratori, 2004; Slijper & Latash, 2004). This task leads to reproducible APAs in most postural muscles.…”

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confidence: 99%

Reversals of anticipatory postural adjustments during voluntary sway in humans

Krishnamoorthy

Latash

2005

The Journal of Physiology

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We describe reversals of anticipatory postural adjustments (APAs) with the phase of a voluntary cyclic whole-body sway movement. Subjects (n = 9) held a standard load in extended arms and released it by a bilateral shoulder abduction motion in a self-paced manner at different phases of the sway. The load release task was also performed during quiet stance in three positions: in the middle of the sway range and close to its extreme forward and backward positions. Larger APAs were seen during the sway task as compared to quiet stance. Although the direction of postural perturbation associated with the load release was always the same, the direction of the APAs in the leg muscles reversed when the subjects were close to the extreme forward position as compared to the APAs in other phases and during quiet stance. The trunk muscles showed smaller APA modulation at the extreme positions but larger modulation when passing through the middle position, depending on the direction of sway, forward or backward. The phenomenon of APA reversals emphasizes the important role of safety in the generation of postural adjustments associated with voluntary movements. Based on these findings, APAs could be defined as changes in the activity of postural muscles associated with a predictable perturbation that act to provide maximal safety of the postural task component.

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The effect of the amplitude of motor action on anticipatory postural adjustments

Cited by 20 publications

References 26 publications

Hand immobilization affects arm and shoulder postural control

Hand immobilization affects arm and shoulder postural control

Teager–Kaiser Energy Operation of Surface EMG Improves Muscle Activity Onset Detection

Reversals of anticipatory postural adjustments during voluntary sway in humans

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