Referent control of anticipatory grip force during reaching in stroke: an experimental and modeling study

Frenkel‐Toledo, Silvi; Yamanaka, Juri; Friedman, Jason; Feldman, Anatol G.; Levin, Mindy F.

doi:10.1007/s00221-019-05498-y

Cited by 13 publications

(6 citation statements)

References 58 publications

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“…Our results could potentially be interpreted by a theory for human motor control that does not necessarily rely on internal models or motor programs. The equilibrium point hypothesis or theory of referent control of action and perception (Feldman, 2016;Frenkel-Toledo et al, 2019;Pilon et al, 2007) proposes that rather than using pre-programed motor commands and efference copies, motor actions occur as certain neurophysiological parameters of the system change. Accordingly, during voluntary actions, the central nervous system changes the spatial thresholds (referent points) at which muscles are activated, and motion emerges as the body is trying to reach the new (shifted) equilibrium point.…”

Section: Discussionmentioning

confidence: 99%

Efference Copy Is Necessary for the Attenuation of Self-Generated Touch

2020

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Self-generated touch feels less intense than external touch of the same intensity. According to theory, this is because the brain predicts and attenuates the somatosensory consequences of our movements using a copy of the motor command, i.e., the efference copy. However, whether the efference copy is necessary for this somatosensory attenuation is unclear. Alternatively, a predictable contact of two body parts could be sufficient. Here we quantified the attenuation of touch applied on the participants' left index finger when the touch was triggered by the active or passive movement of the right index finger and when it was externally generated. We observed attenuation only when the touch was triggered by the participants' active movement. In contrast, during the passive movement, the touch was perceived to be as strong as when the touch was externally triggered. Our results suggest that the efference copy is necessary for the attenuation of self-generated touch.

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Section: Discussionmentioning

confidence: 99%

Efference Copy Is Necessary for the Attenuation of Self-Generated Touch

2020

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“…It can be carefully assumed that healthy individuals anticipate and scale the force needed to apply before lifting a cup, as opposed to post-stroke participants, who produced less force per unit of time, which suggests an altered anticipation and preparation for lifting. This interpretation is supported by Nowak et al 81 , who assert that when known objects are grasped and lifted, predictive force control is used, and by Frenkel-Toledo et al 82 , who reported decreased task-specific adaptability among stroke participants. Our study has shown that this ability is altered with increasing stroke severity.…”

Section: Discussionmentioning

confidence: 83%

The effects of an object’s height and weight on force calibration and kinematics when post-stroke and healthy individuals reach and grasp

Polak

Yelkin

Edelman

et al. 2021

Sci Rep

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Impairment in force regulation and motor control impedes the independence of individuals with stroke by limiting their ability to perform daily activities. There is, at present, incomplete information about how individuals with stroke regulate the application of force and control their movement when reaching, grasping, and lifting objects of different weights, located at different heights. In this study, we assess force regulation and kinematics when reaching, grasping, and lifting a cup of two different weights (empty and full), located at three different heights, in a total of 46 participants: 30 sub-acute stroke participants, and 16 healthy individuals. We found that the height of the reached target affects both force calibration and kinematics, while its weight affects only the force calibration when post-stroke and healthy individuals perform a reach-to-grasp task. There was no difference between the two groups in the mean and peak force values. The individuals with stroke had slower, jerkier, less efficient, and more variable movements compared to the control group. This difference was more pronounced with increasing stroke severity. With increasing stroke severity, post-stroke individuals demonstrated altered anticipation and preparation for lifting, which was evident for either cortical lesion side.

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“…During (Ahead of Print) unimanual gripping of a solid object, the actual hand aperture (Q) is defined by the object's size. The referent aperture (R) is smaller such that at position R, the fingers virtually penetrate the object (Figure 4a; see also Frenkel-Toledo et al, 2019). The grip force is defined by the difference between Q and R. The smaller the R, the larger the grip force.…”

Section: Considering Results Based On the Notion Of Indirect Parametric Control Of Motor Actions And Sensory Influences By The M1mentioning

confidence: 99%

Effect of Object Texture and Weight on Ipsilateral Corticospinal Influences During Bimanual Holding in Humans

et al. 2022

Self Cite

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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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Referent control of anticipatory grip force during reaching in stroke: an experimental and modeling study

Cited by 13 publications

References 58 publications

Efference Copy Is Necessary for the Attenuation of Self-Generated Touch

Efference Copy Is Necessary for the Attenuation of Self-Generated Touch

The effects of an object’s height and weight on force calibration and kinematics when post-stroke and healthy individuals reach and grasp

Effect of Object Texture and Weight on Ipsilateral Corticospinal Influences During Bimanual Holding in Humans

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