Are speed/accuracy trade-offs caused by neuromotor noise, or not?

Jong, Willem P. de; Galen, G.P. van

doi:10.1017/s0140525x97251447

Cited by 2 publications

(1 citation statement)

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“…In reaching to a target, the maximum allowable noise is related to the target width (i.e., spatial tolerance) and the signal size is related to the movement speed. From cortical neurons to motor units of muscles, noise is an inherent property of all parts of the motor system (De Jong and Galen, 1997). Noise during the movement execution has been identified as the primary cause of movement variability in healthy individuals (van Beers et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

Consequences of increased neuromotor noise for reaching movements in persons with stroke

McCrea

Eng

2004

Exp Brain Res

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Understanding stroke-induced changes to the motor control of the more affected arm of people with stroke may lead to more effective rehabilitation interventions that improve function. Reaching movements of the more affected arm in persons with stroke are slow, segmented and indirect. Such changes may be related to a reduced capacity to transmit motor commands in the presence of neuromotor noise. In tasks requiring both speed and accuracy, transmission capacity can be characterized by the linear relationship between movement time and task difficulty (Fitts' law). This study quantified Fitts' slope and intercept coefficients in stroke during reaching tasks and their relationship to kinematic measures of path accuracy (directness), trajectory corrections (segmentation), and planning strategy (skewness). We compared Fitts' slope and intercept and kinematics among the more and less affected arm of twenty persons with stroke and the nondominant arm of ten healthy persons. Slope and intercept were significantly increased in the more affected arm of the group with stroke and related to clinical measurements of motor impairment and tone. For both the more and less affected arm of the group with stroke, increased slopes and intercepts were correlated to more indirect, segmented, and positively skewed movement. Our findings suggest that stroke results in greater neuromotor noise which has consequences on both motor execution and planning. Individuals with stroke demonstrate substantially more deviation from straight-line paths than controls, despite using more conservative strategies (i.e., leftward shift of velocity profile) and extensive feedback control (i.e., segmentation).

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Section: Introductionmentioning

confidence: 99%

Consequences of increased neuromotor noise for reaching movements in persons with stroke

McCrea

Eng

2004

Exp Brain Res

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Difficulty-dependent trajectory planning during target-reaching movements

Yang

Song

2015

2015 37th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC)

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This study explored how the difficulty of a task influenced motor control during target-reaching movements. During the experiment, twelve healthy subjects were recruited to perform target-reaching tasks with three different target sizes over three distances as quickly and accurately as possible using their index fingers. There were nine levels of difficulty of the tasks, with a combination of three target sizes and three distances, and the difficulty of the tasks could be measured by Fitts' law in terms of the index of difficulty (ID). The kinematic variables to represent movement performance were peak velocity (Vpeak), percentage time to peak velocity (PTPV), normalized jerk score (NJS) and fApEn (fuzzy approximate entropy). The results showed both distance and target size significantly influenced these parameters with the exception of the effect of the target size on Vpeak. Vpeak and fApEn were only linearly related to the ID when the individual target size across movement distances was considered. And a linear relationship between PTPV or NJS and ID was found. The increase in the difficulty of the task could lead to a shift from feedforward to feedback control by the central nerve system. The findings in this study contribute to an understanding of the underlying motor control during target reaching movements and can be applied as a quantitative method of evaluation in the clinic in the future.

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Are speed/accuracy trade-offs caused by neuromotor noise, or not?

Cited by 2 publications

References 0 publications

Consequences of increased neuromotor noise for reaching movements in persons with stroke

Consequences of increased neuromotor noise for reaching movements in persons with stroke

Difficulty-dependent trajectory planning during target-reaching movements

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