Threshold position control and the principle of minimal interaction in motor actions

We tested the hypothesis that the ipsilateral corticospinal system, like the contralateral corticospinal system, controls the threshold muscle length at which wrist muscles and the stretch reflex begin to act during holding tasks. Transcranial magnetic stimulation was applied over the right primary motor cortex in 21 healthy subjects holding a smooth or coarse block between the hands. Regardless of the lifting force, motor evoked potentials in right wrist flexors were larger for the smooth block. This result was explained based on experimental evidence that motor actions are controlled by shifting spatial stretch reflex thresholds. Thus, the ipsilateral corticospinal system is involved in threshold position control by modulating facilitatory influences of hand skin afferents on motoneurons of wrist muscles during bimanual object manipulation.

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Threshold position control of anticipation in humans: a possible role of corticospinal influences

The Journal of Physiology ◽

10.1113/jp274309 ◽

2017 ◽

Vol 595 (15) ◽

pp. 5359-5374 ◽

Cited By ~ 6

Author(s):

Lei Zhang ◽

Nicolas A. Turpin ◽

Anatol G. Feldman

Keyword(s):

Position Control ◽

Threshold Position

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Threshold position control signifies a common spatial frame of reference for motor action and kinesthesia

Brain Research Bulletin ◽

10.1016/j.brainresbull.2007.12.002 ◽

2008 ◽

Vol 75 (5) ◽

pp. 497-499 ◽

Cited By ~ 8

Author(s):

Anatol G. Feldman

Keyword(s):

Position Control ◽

Frame Of Reference ◽

Motor Action ◽

Spatial Frame ◽

Threshold Position

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Threshold position control of arm movement with anticipatory increase in grip force

Experimental Brain Research ◽

10.1007/s00221-007-0901-8 ◽

2007 ◽

Vol 181 (1) ◽

pp. 49-67 ◽

Cited By ~ 62

Author(s):

Jean-François Pilon ◽

Sophie J. De Serres ◽

Anatol G. Feldman

Keyword(s):

Grip Force ◽

Position Control ◽

Arm Movement ◽

Threshold Position

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Under Threshold Position Control, Peripheral Mechanisms Compensate Efficiently for Small Perturbations of Arm Movements

Motor Control ◽

10.1123/mc.2014-0084 ◽

2016 ◽

Vol 20 (1) ◽

pp. 87-108 ◽

Cited By ~ 4

Author(s):

Lei Zhang ◽

Andreas Straube ◽

Thomas Eggert

Keyword(s):

Position Control ◽

Dynamic Responses ◽

Central Control ◽

Movement Trajectory ◽

Muscle Properties ◽

Small Perturbations ◽

Intrinsic Muscle ◽

Threshold Position ◽

Good Agreement

Unexpected small perturbations during reaching movements are normally compensated for automatically. Previous studies of such perturbations observed that the movement trajectory converges back to the preplanned end position. The question remains whether peripheral mechanisms formed by intrinsic muscle properties and stretch reflex are efficient for compensating for such perturbations. Even though this is suggested by a threshold position control model highlighting the role of peripheral mechanisms under central control in movement generation, it is neither developed nor extensively tested for this capability. The present study tests how this model can account for the compensation during single-joint fast reaching. Motor responses to transient, unpredictable, small perturbations at different movement phases were measured and compared with the model predictions. The results show good agreement concerning kinematic and dynamic responses. Simulations with altered mechanical parameters of the model suggest that reflexive responses are well tuned to the intrinsic muscle properties. We conclude that under central control, peripheral mechanisms cope efficiently with small transient perturbations.

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