Compensatory properties of visual information in the control of isometric force

Hong, S. Lee; Brown, Amber J.; Newell, Karl M.

doi:10.3758/pp.70.2.306

Cited by 32 publications

(18 citation statements)

References 29 publications

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“…That the opposite task was found to have the shorter TTF (i.e. force-matching <position-matching) in comparison to most reports, supports the conclusion of a task specific difference in central neural command in motor unit recruitment [5], [17], [87]; however, the source of the task specificity may be due to factors other than load compliance such as the amount of stabilization provided to the body and limb and the corrective demand driven by the sensitivity of the visual feedback within the same range of gain [85], [86].…”

Section: Resultssupporting

confidence: 69%

“…From a motor control perspective, both of these tasks can be considered to be analogous to a sustained visuomotor tracking task because the only way the subject knows that the force output is correct is through constant visual feedback [84]–[86]. From prior studies, the shorter duration task is considered to be the more difficult task by subjects during task performance even though the mechanical demands, torque output, and amount of muscle fatigue at task failure are equivalent between the two tasks [12], [15].…”

Section: Discussionmentioning

confidence: 99%

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Cortical and Spinal Mechanisms of Task Failure of Sustained Submaximal Fatiguing Contractions

2014

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In this and the subsequent companion paper, results are presented that collectively seek to delineate the contribution that supraspinal circuits have in determining the time to task failure (TTF) of sustained submaximal contractions. The purpose of this study was to compare adjustments in supraspinal and spinal excitability taken concurrently throughout the performance of two different fatigue tasks with identical mechanical demands but different TTF (i.e., force-matching and position-matching tasks). On separate visits, ten healthy volunteers performed the force-matching or position-matching task at 15% of maximum strength with the elbow flexors to task failure. Single-pulse transcranial magnetic stimulation (TMS), paired-pulse TMS, paired cortico-cervicomedullary stimulation, and brachial plexus electrical stimulation were delivered in a 6-stimuli sequence at baseline and every 2–3 minutes throughout fatigue-task performance. Contrary to expectations, the force-matching task TTF was 42% shorter (17.5±7.9 min) than the position-matching task (26.9±15.11 min; p<0.01); however, both tasks caused the same amount of muscle fatigue (p = 0.59). There were no task-specific differences for the total amount or rate of change in the neurophysiologic outcome variables over time (p>0.05). Therefore, failure occurred after a similar mean decline in motorneuron excitability developed (p<0.02, ES = 0.35–0.52) coupled with a similar mean increase in measures of corticospinal excitability (p<0.03, ES = 0.30–0.41). Additionally, the amount of intracortical inhibition decreased (p<0.03, ES = 0.32) and the amount of intracortical facilitation (p>0.10) and an index of upstream excitation of the motor cortex remained constant (p>0.40). Together, these results suggest that as fatigue develops prior to task failure, the increase in corticospinal excitability observed in relationship to the decrease in spinal excitability results from a combination of decreasing intracortical inhibition with constant levels of intracortical facilitation and upstream excitability that together eventually fail to provide the input to the motor cortex necessary for descending drive to overcome the spinal cord resistance, thereby contributing to task failure.

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Section: Resultssupporting

confidence: 69%

Section: Discussionmentioning

confidence: 99%

Cortical and Spinal Mechanisms of Task Failure of Sustained Submaximal Fatiguing Contractions

2014

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“…The results of this study provide support for the uncertainty compensation hypothesis [26], [29], [34], [35], extending it to human attention. Specifically, the entropy of the RT and fixation durations changed in a compensatory manner to one another, where: 1) Information Entropy of RT increased as the spatial and temporal uncertainty of the stimuli increased; and 2) Information Entropy of the fixation durations decreased as the uncertainty of the stimuli increased.…”

Section: Discussionsupporting

confidence: 73%

“…This finding holds for both spatial [29]–[32] and temporal [28], [29], [33] uncertainties in visual feedback. These findings provided the basis for the uncertainty compensation hypothesis , where uncertainty is compensated across task, organism, and environment [26], [29], [34], [35]. As a result, we will conduct a preliminary test of whether this conceptual framework with uncertainty at its center can be extended to an attention task, and will be evident in the distributions of RTs and fixation durations.…”

Section: Introductionmentioning

confidence: 53%

“…Hong et al [29] have demonstrated that as the likelihood of obtaining visual feedback in space and time, the uncertainty contained in the force output decreased, reflective of fewer corrections being made to the force generated by the muscles. A majority of the variance in the data could be captured by a quadratic surface that showed that the muscle force patterns were similar when the spatial uncertainty of the visual feedback was high and temporal uncertainty was low and vice versa.…”

Section: Introductionmentioning

confidence: 99%

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Uncertainty Compensation in Human Attention: Evidence from Response Times and Fixation Durations

Hong

Beck

2010

PLoS ONE

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BackgroundUncertainty and predictability have remained at the center of the study of human attention. Yet, studies have only examined whether response times (RT) or fixations were longer or shorter under levels of stimulus uncertainty. To date, no study has examined patterns of stimuli and responses through a unifying framework of uncertainty.Methodology/Principal FindingsWe asked 29 college students to generate repeated responses to a continuous series of visual stimuli presented on a computer monitor. Subjects produced these responses by pressing on a keypad as soon a target was detected (regardless of position) while the durations of their visual fixations were recorded. We manipulated the level of stimulus uncertainty in space and time by changing the number of potential stimulus locations and time intervals between stimulus presentations. To allow the analyses to be conducted using uncertainty as common description of stimulus and response we calculated the entropy of the RT and fixation durations. We tested the hypothesis of uncertainty compensation across space and time by fitting the RT and fixation duration entropy values to a quadratic surface. The quadratic surface accounted for 80% of the variance in the entropy values of both RT and fixation durations. RT entropy increased as a function of spatial and temporal uncertainty of the stimulus, alongside a symmetric, compensatory decrease in the entropy of fixation durations as the level of spatial and temporal uncertainty of the stimuli was increased.Conclusions/SignificanceOur results demonstrate that greater uncertainty in the stimulus leads to greater uncertainty in the response, and that the effects of spatial and temporal uncertainties are compensatory. We also observed compensatory relationship across the entropies of fixation duration and RT, suggesting that a more predictable visual search strategy leads to more uncertain response patterns and vice versa.

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Complexity in Movement Disorders: A Systems Approach to Intervention

Hong

2012

Handbook of Systems and Complexity in Health

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Compensatory properties of visual information in the control of isometric force

Cited by 32 publications

References 29 publications

Cortical and Spinal Mechanisms of Task Failure of Sustained Submaximal Fatiguing Contractions

Cortical and Spinal Mechanisms of Task Failure of Sustained Submaximal Fatiguing Contractions

Uncertainty Compensation in Human Attention: Evidence from Response Times and Fixation Durations

Complexity in Movement Disorders: A Systems Approach to Intervention

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