scholarly journals Role of post-trial visual feedback on unintentional force drift during isometric finger force production tasks

2019 ◽  
Author(s):  
S Balamurugan ◽  
Dhanush Rachaveti ◽  
Varadhan SKM
Keyword(s):  
Visual Feedback ◽  
Visual Information ◽  
Force Production ◽  
Finger Force ◽  
Visual Occlusion ◽  
Referent Configuration ◽  
Central Controller ◽  
Post Trial ◽  
Lower Magnitude ◽  
The Right

AbstractForce produced during an isometric finger force production task tends to drift towards a lower magnitude when visual information is occluded. This phenomenon of drift in force without one’s awareness is called unintentional drift. The present study used epilogue, a particular case of post-trial visual feedback, and compared the unintentional drift for two conditions, i.e., with and without the epilogue. For this purpose, fourteen healthy participants were recruited for the experiments and were instructed to produce fingertip forces using four fingers of the right hand with the target line at 15% MVC. A trial lasted for sixteen seconds, where for the initial eight seconds, there is visual feedback followed by the visual occlusion period. The results showed a significant reduction in unintentional drift for the condition involving epilogue when compared to no epilogue. This reduction in drift is due to the shift in the referent configuration parameter by the phenomenon of RC back coupling. Further, we also claim that there might be a distribution of λs or RCs, based on the history of tuning of the control parameter by the central controller. This distribution of λs selected by the central controller in a redundant environment based on the epilogue resulted in a reduction of unintentional drift.

scholarly journals Role of Post-Trial Visual Feedback on Unintentional Force Drift During Isometric Finger Force Production Tasks

Motor Control ◽  
2021 ◽  
pp. 1-14
Author(s):  
S. Balamurugan ◽  
Rachaveti Dhanush ◽  
S.K.M. Varadhan
Keyword(s):  
Visual Feedback ◽  
Maximum Voluntary Contraction ◽  
Control Variable ◽  
Force Production ◽  
Voluntary Contraction ◽  
Central Controller ◽  
The Difference ◽  
Post Trial ◽  
Fingertip Forces

A reduction in fingertip forces during a visually occluded isometric task is called unintentional drift. In this study, unintentional drift was studied for two conditions, with and without “epilogue.” We define epilogue as the posttrial visual feedback in which the outcome of the just-concluded trial is shown before the start of the next trial. For this study, 14 healthy participants were recruited and were instructed to produce fingertip forces to match a target line at 15% maximum voluntary contraction. The results showed a significant reduction in unintentional drift in the epilogue condition. This reduction is probably due to the difference in the shift in λ, the threshold of the tonic stretch reflex, the hypothetical control variable that the central controller can set.

Intermittency in the Control of Continuous Force Production

2000 ◽  
Vol 84 (4) ◽  
pp. 1708-1718 ◽  
Author(s):  
Andrew B. Slifkin ◽  
David E. Vaillancourt ◽  
Karl M. Newell
Keyword(s):  
Visual Feedback ◽  
Visual Information ◽  
Spectral Power ◽  
Force Production ◽  
Motor Output ◽  
Force Variability ◽  
Force Output ◽  
Feedback Information ◽  
Information Processes ◽  
Feedback Frequency

The purpose of the current investigation was to examine the influence of intermittency in visual information processes on intermittency in the control continuous force production. Adult human participants were required to maintain force at, and minimize variability around, a force target over an extended duration (15 s), while the intermittency of on-line visual feedback presentation was varied across conditions. This was accomplished by varying the frequency of successive force-feedback deliveries presented on a video display. As a function of a 128-fold increase in feedback frequency (0.2 to 25.6 Hz), performance quality improved according to hyperbolic functions (e.g., force variability decayed), reaching asymptotic values near the 6.4-Hz feedback frequency level. Thus, the briefest interval over which visual information could be integrated and used to correct errors in motor output was approximately 150 ms. The observed reductions in force variability were correlated with parallel declines in spectral power at about 1 Hz in the frequency profile of force output. In contrast, power at higher frequencies in the force output spectrum were uncorrelated with increases in feedback frequency. Thus, there was a considerable lag between the generation of motor output corrections (1 Hz) and the processing of visual feedback information (6.4 Hz). To reconcile these differences in visual and motor processing times, we proposed a model where error information is accumulated by visual information processes at a maximum frequency of 6.4 per second, and the motor system generates a correction on the basis of the accumulated information at the end of each 1-s interval.

Timing and visual feedback constraints on repetitive finger force production

2009 ◽  
Vol 201 (4) ◽  
pp. 673-679 ◽  
Author(s):  
Amanda S. Therrien ◽  
Ramesh Balasubramaniam
Keyword(s):  
Visual Feedback ◽  
Force Production ◽  
Finger Force

scholarly journals Force illusions and drifts observed during muscle vibration

2018 ◽  
Vol 119 (1) ◽  
pp. 326-336 ◽  
Author(s):  
Sasha Reschechtko ◽  
Cristian Cuadra ◽  
Mark L. Latash
Keyword(s):  
Visual Feedback ◽  
Force Production ◽  
The Other ◽  
Muscle Vibration ◽  
Finger Force ◽  
Force Perception ◽  
Other Hand ◽  
Referent Coordinate ◽  
Perceived Force ◽  
Frame Set

We explored predictions of a scheme that views position and force perception as a result of measuring proprioceptive signals within a reference frame set by ongoing efferent process. In particular, this hypothesis predicts force illusions caused by muscle vibration and mediated via changes in both afferent and efferent components of kinesthesia. Healthy subjects performed accurate steady force production tasks by pressing with the four fingers of one hand (the task hand) on individual force sensors with and without visual feedback. At various times during the trials, subjects matched the perceived force using the other hand. High-frequency vibration was applied to one or both of the forearms (over the hand and finger extensors). Without visual feedback, subjects showed a drop in the task hand force, which was significantly smaller under the vibration of that forearm. Force production by the matching hand was consistently higher than that of the task hand. Vibrating one of the forearms affected the matching hand in a manner consistent with the perception of higher magnitude of force produced by the vibrated hand. The findings were consistent between the dominant and nondominant hands. The effects of vibration on both force drift and force mismatching suggest that vibration led to shifts in both signals from proprioceptors and the efferent component of perception, the referent coordinate and/or coactivation command. The observations fit the hypothesis on combined perception of kinematic-kinetic variables with little specificity of different groups of peripheral receptors that all contribute to perception of forces and coordinates. NEW & NOTEWORTHY We show that vibration of hand/finger extensors produces consistent errors in finger force perception. Without visual feedback, finger force drifted to lower values without a drift in the matching force produced by the other hand; hand extensor vibration led to smaller finger force drift. The findings fit the scheme with combined perception of kinematic-kinetic variables and suggest that vibration leads to consistent shifts of the referent coordinate and, possibly, of coactivation command to the effector.

scholarly journals On the nature of unintentional action: a study of force/moment drifts during multifinger tasks

2016 ◽  
Vol 116 (2) ◽  
pp. 698-708 ◽  
Author(s):  
Behnoosh Parsa ◽  
Daniel J. O'Shea ◽  
Vladimir M. Zatsiorsky ◽  
Mark L. Latash
Keyword(s):  
Visual Feedback ◽  
Sensory Information ◽  
Force Production ◽  
Total Force ◽  
Total Moment ◽  
Individual Finger ◽  
Referent Coordinate ◽  
Force Moment ◽  
Finger Forces ◽  
The Right

We explored the origins of unintentional changes in performance during accurate force production in isometric conditions seen after turning visual feedback off. The idea of control with referent spatial coordinates suggests that these phenomena could result from drifts of the referent coordinate for the effector. Subjects performed accurate force/moment production tasks by pressing with the fingers of a hand on force sensors. Turning the visual feedback off resulted in slow drifts of both total force and total moment to lower magnitudes of these variables; these drifts were more pronounced in the right hand of the right-handed subjects. Drifts in individual finger forces could be in different direction; in particular, fingers that produced moments of force against the required total moment showed an increase in their forces. The force/moment drift was associated with a drop in the index of synergy stabilizing performance under visual feedback. The drifts in directions that changed performance (non-motor equivalent) and in directions that did not (motor equivalent) were of about the same magnitude. The results suggest that control with referent coordinates is associated with drifts of those referent coordinates toward the corresponding actual coordinates of the hand, a reflection of the natural tendency of physical systems to move toward a minimum of potential energy. The interaction between drifts of the hand referent coordinate and referent orientation leads to counterdirectional drifts in individual finger forces. The results also demonstrate that the sensory information used to create multifinger synergies is necessary for their presence over the task duration.

scholarly journals A Connectome-Wide Functional Signature of Trait Anger

2021 ◽  
pp. 216770262110302
Author(s):  
M. Justin Kim ◽  
Maxwell L. Elliott ◽  
Annchen R. Knodt ◽  
Ahmad R. Hariri
Keyword(s):  
Functional Connectivity ◽  
Visual Information ◽  
Past Research ◽  
Brain Regions ◽  
Small Sample ◽  
Trait Anger ◽  
Frontal Pole ◽  
Brain Correlates ◽  
Small Sample Sizes ◽  
The Right

Past research on the brain correlates of trait anger has been limited by small sample sizes, a focus on relatively few regions of interest, and poor test–retest reliability of functional brain measures. To address these limitations, we conducted a data-driven analysis of variability in connectome-wide functional connectivity in a sample of 1,048 young adult volunteers. Multidimensional matrix regression analysis showed that self-reported trait anger maps onto variability in the whole-brain functional connectivity patterns of three brain regions that serve action-related functions: bilateral supplementary motor areas and the right lateral frontal pole. We then demonstrate that trait anger modulates the functional connectivity of these regions with canonical brain networks supporting somatomotor, affective, self-referential, and visual information processes. Our findings offer novel neuroimaging evidence for interpreting trait anger as a greater propensity to provoked action, which supports ongoing efforts to understand its utility as a potential transdiagnostic marker for disordered states characterized by aggressive behavior.

scholarly journals Aging differentially affects online control and offline control in finger force production

PLoS ONE ◽  
2018 ◽  
Vol 13 (5) ◽  
pp. e0198084
Author(s):  
Yang Sun Park ◽  
Kyung Koh ◽  
Hyun Joon Kwon ◽  
Okjin Lee ◽  
Jae Kun Shim
Keyword(s):  
Force Production ◽  
Online Control ◽  
Finger Force

The effects of stroke and age on finger interaction in multi-finger force production tasks

2003 ◽  
Vol 114 (9) ◽  
pp. 1646-1655 ◽  
Author(s):  
Sheng Li ◽  
Mark L Latash ◽  
Guang H Yue ◽  
Vlodek Siemionow ◽  
Vinod Sahgal
Keyword(s):  
Force Production ◽  
Finger Force

Out of Compassion of Out of Rights? A Story about an Amyotrophic Lateral Sclerosis (ALS) Human Clinical Trial

2021 ◽  
Vol 8 (3) ◽  
pp. 1-23
Author(s):  
Hedva Eyal
Keyword(s):  
Clinical Trial ◽  
Compassionate Use ◽  
Human Clinical Trial ◽  
Biotech Company ◽  
Patient Organisations ◽  
Informed Consent Form ◽  
Trial Treatment ◽  
Post Trial ◽  
The Right ◽  
Lateral Sclerosis

This article examines the intersection of compassion and rights, and how the two concepts are constituted and wielded in the context of human clinical trials. Doron, an ALS patient who was recruited to a clinical trial, believed that he had the right to post-trial treatment according to the wording of an informed consent form he signed before joining the trial. However, the biotech company sponsoring the trial instead offered him ‘compassionate use’ access, i.e., access at its discretion rather than as a legal obligation on its part. I argue that under a ‘bioeconomy of value’, the human clinical trial regime has been subordinated to two competing discourses: that of compassion and that of patients’ rights. Both are interpreted and deployed differently by the different stakeholders, namely the patient, the biotech company, and the medical establishment. I argue that the adoption, by bioeconomy actors, of a social value discourse of compassion is designed to preserve a hierarchy that deprives the patient of their power and their rights. Simultaneously, this practice highlights the power of the biotech industry as a moral partner and ‘saviour’ in its relationship with patient organisations and its role as a medical–scientific actor in the Israeli healthcare system.

scholarly journals Intermittent Visuomotor Processing in the Human Cerebellum, Parietal Cortex, and Premotor Cortex

2006 ◽  
Vol 95 (2) ◽  
pp. 922-931 ◽  
Author(s):  
David E. Vaillancourt ◽  
Mary A. Mayka ◽  
Daniel M. Corcos
Keyword(s):  
Parietal Cortex ◽  
Visual Feedback ◽  
Visual Information ◽  
Grip Force ◽  
Premotor Cortex ◽  
Force Variability ◽  
Neural Activation ◽  
Control Force ◽  
Force Condition ◽  
Visuomotor Processing

The cerebellum, parietal cortex, and premotor cortex are integral to visuomotor processing. The parameters of visual information that modulate their role in visuomotor control are less clear. From motor psychophysics, the relation between the frequency of visual feedback and force variability has been identified as nonlinear. Thus we hypothesized that visual feedback frequency will differentially modulate the neural activation in the cerebellum, parietal cortex, and premotor cortex related to visuomotor processing. We used functional magnetic resonance imaging at 3 Tesla to examine visually guided grip force control under frequent and infrequent visual feedback conditions. Control conditions with intermittent visual feedback alone and a control force condition without visual feedback were examined. As expected, force variability was reduced in the frequent compared with the infrequent condition. Three novel findings were identified. First, infrequent (0.4 Hz) visual feedback did not result in visuomotor activation in lateral cerebellum (lobule VI/Crus I), whereas frequent (25 Hz) intermittent visual feedback did. This is in contrast to the anterior intermediate cerebellum (lobule V/VI), which was consistently active across all force conditions compared with rest. Second, confirming previous observations, the parietal and premotor cortices were active during grip force with frequent visual feedback. The novel finding was that the parietal and premotor cortex were also active during grip force with infrequent visual feedback. Third, right inferior parietal lobule, dorsal premotor cortex, and ventral premotor cortex had greater activation in the frequent compared with the infrequent grip force condition. These findings demonstrate that the frequency of visual information reduces motor error and differentially modulates the neural activation related to visuomotor processing in the cerebellum, parietal cortex, and premotor cortex.

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