scholarly journals A switching cost for motor planning

2016 ◽  
Author(s):  
Jean-Jacques Orban de Xivry ◽  
Philippe Lefèvre
Keyword(s):  
Cognitive Task ◽  
Motor Planning ◽  
Motor Program ◽  
Switching Cost ◽  
Movement Planning ◽  
Optimal Feedback Control ◽  
Cognitive Studies ◽  
Individual Trial ◽  
Selection By Consequences ◽  
Trial Basis

AbstractMovement planning consists of choosing the endpoint of the movement and selecting the motor program that will bring the effector on the endpoint. It is widely accepted that movement endpoint is updated on a trial-by-trial basis with respect to the observed errors and that the motor program for a given movement follows the rules of optimal feedback control. Here, we show clear limitations of these predictions because of the existence of a switching cost for motor planning. First, this cost prevented participants from tuning their motor program appropriately for each individual trial. This was true even when the participants selected the width of the target that they reached toward or when they had learned the appropriate motor program previously. These data are compatible with the existence of a switching cost such as those found in cognitive studies. Interestingly, this cost of switching shares many features of costs reported in cognitive task switching experiments and, when tested in the same participants, was correlated with it. Second, we found that randomly changing the width of a target over the course of a reaching experiment prevents the motor system from updating the endpoint of movements on the basis of the performance on the previous trial if the width of the target has changed. These results provide new insights into the process of motor planning and how it relates to optimal control theory and to a selection by consequences process rather than to an error-based process for action selection.

scholarly journals A switching cost for motor planning

2016 ◽  
Vol 116 (6) ◽  
pp. 2857-2868 ◽  
Author(s):  
Jean-Jacques Orban de Xivry ◽  
Philippe Lefèvre
Keyword(s):  
Optimal Control Theory ◽  
Motor System ◽  
Cognitive Task ◽  
Motor Planning ◽  
Motor Program ◽  
Switching Cost ◽  
Movement Planning ◽  
Optimal Feedback Control ◽  
Individual Trial ◽  
Trial Basis

Movement planning consists of choosing the intended endpoint of the movement and selecting the motor program that will bring the effector on the endpoint. It is widely accepted that movement endpoint is updated on a trial-by-trial basis with respect to the observed errors and that the motor program for a given movement follows the rules of optimal feedback control. In this article, we show clear limitations of these theories. First, participants in the current study could not tune their motor program appropriately for each individual trial. This was true even when the participants selected the width of the target that they reached toward or when they had learned the appropriate motor program previously. These data are compatible with the existence of a switching cost for motor planning, which relates to the drop in performance due to an imposed switch of motor programs. This cost of switching shares many features of costs reported in cognitive task switching experiments and, when tested in the same participants, was correlated with it. Second, we found that randomly changing the width of a target over the course of a reaching experiment prevents the motor system from updating the endpoint of movements on the basis of the performance on the previous trial if the width of the target has changed. These results provide new insights into the process of motor planning and how it relates to optimal control theory and to an action selection based on the reward consequences of the motor program rather than that based on the observed error.

scholarly journals Manifold reaching paradigm: how do we handle target redundancy?

2011 ◽  
Vol 106 (4) ◽  
pp. 2086-2102 ◽  
Author(s):  
Bastien Berret ◽  
Enrico Chiovetto ◽  
Francesco Nori ◽  
Thierry Pozzo
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Degrees Of Freedom ◽  
A Priori ◽  
Movement Planning ◽  
Optimal Feedback Control ◽  
Target Redundancy ◽  
The Central Nervous System ◽  
Point To Point ◽  
Muscle Activations

How the central nervous system coordinates the many intrinsic degrees of freedom of the musculoskeletal system is a recurrent question in motor control. Numerous studies addressed it by considering redundant reaching tasks such as point-to-point arm movements, for which many joint trajectories and muscle activations are usually compatible with a single goal. There exists, however, a different, extrinsic kind of redundancy that is target redundancy. Many times, indeed, the final point to reach is neither specified nor unique. In this study, we aim to understand how the central nervous system tackles such an extrinsic redundancy by considering a reaching-to-a-manifold paradigm, more specifically an arm pointing to a long vertical bar. In this case, the endpoint is not defined a priori and, therefore, subjects are free to choose any point on the bar to successfully achieve the task. We investigated the strategies used by subjects to handle this presented choice. Our results indicate both intersubject and intertrial consistency with respect to the freedom provided by the task. However, the subjects' behavior is found to be more variable than during classical point-to-point reaches. Interestingly, the average arm trajectories to the bar and the structure of intertrial endpoint variations could be explained via stochastic optimal control with an energy/smoothness expected cost and signal-dependent motor noise. We conclude that target redundancy is first overcome during movement planning and then exploited during movement execution, in agreement with stochastic optimal feedback control principles, which illustrates how the complementary problems of goal and movement selection may be resolved at once.

scholarly journals Motor planning brings human primary somatosensory cortex into action-specific preparatory states

eLife ◽  
2022 ◽  
Vol 11 ◽  
Author(s):  
Giacomo Ariani ◽  
J Andrew Pruszynski ◽  
Jörn Diedrichsen
Keyword(s):  
Somatosensory Cortex ◽  
Motor Neurons ◽  
Primary Motor Cortex ◽  
Specific Activity ◽  
Activity Patterns ◽  
Critical Role ◽  
Motor Planning ◽  
Movement Control ◽  
Movement Planning ◽  
Primary Somatosensory Cortex

Motor planning plays a critical role in producing fast and accurate movement. Yet, the neural processes that occur in human primary motor and somatosensory cortex during planning, and how they relate to those during movement execution, remain poorly understood. Here we used 7T functional magnetic resonance imaging (fMRI) and a delayed movement paradigm to study single finger movement planning and execution. The inclusion of no-go trials and variable delays allowed us to separate what are typically overlapping planning and execution brain responses. Although our univariate results show widespread deactivation during finger planning, multivariate pattern analysis revealed finger-specific activity patterns in contralateral primary somatosensory cortex (S1), which predicted the planned finger action. Surprisingly, these activity patterns were as informative as those found in contralateral primary motor cortex (M1). Control analyses ruled out the possibility that the detected information was an artifact of subthreshold movements during the preparatory delay. Furthermore, we observed that finger-specific activity patterns during planning were highly correlated to those during execution. These findings reveal that motor planning activates the specific S1 and M1 circuits that are engaged during the execution of a finger press, while activity in both regions is overall suppressed. We propose that preparatory states in S1 may improve movement control through changes in sensory processing or via direct influence of spinal motor neurons.

scholarly journals Modulation of Initial Movement for Double Potential Targets With Specific Time Constraints

2021 ◽  
Author(s):  
Ryoji Onagawa ◽  
Kazutoshi Kudo
Keyword(s):  
Motor Planning ◽  
Time Constraint ◽  
Movement Planning ◽  
Time Constraints ◽  
Specific Time ◽  
Target Condition ◽  
Single Target ◽  
Goal Directed Behavior ◽  
Initial Movement

Abstract In goal-directed behavior, individuals are often required to plan and execute a movement with multiple competing reach targets simultaneously. The time constraint assigned to the target is an important factor that affect the initial movement planning, but the adjustments made to the starting behavior considering the time constraints specific to each target have not yet been clarified. The current study examined how humans adjusted their motor planning for double potential targets with independent time constraints under a go-before-you-know situation. The results revealed that the initial movements were modulated depending on the time constraints for potential targets. However, under tight time constraints, the performance in the double-target condition was lower than the single-target condition, which was a control condition implemented to estimate performance when one target is ignored. These results indicate that the initial movement for multiple potential targets with independent time constraints can be modified, but the planning is suboptimal.

scholarly journals Prolonged response time helps eliminate residual errors in visuomotor adaptation

2021 ◽  
Author(s):  
Lisa Langsdorf ◽  
Jana Maresch ◽  
Mathias Hegele ◽  
Samuel D. McDougle ◽  
Raphael Schween
Keyword(s):  
Cognitive Strategies ◽  
Motor Planning ◽  
Visuomotor Adaptation ◽  
Movement Planning ◽  
Planning Time ◽  
Full Compensation ◽  
Speed Accuracy ◽  
Residual Errors ◽  
Prolonged Response ◽  
Accuracy Tradeoff

AbstractOne persistent curiosity in visuomotor adaptation tasks is that participants often do not reach maximal performance. This incomplete asymptote has been explained as a consequence of obligatory computations within the implicit adaptation system, such as an equilibrium between learning and forgetting. A body of recent work has shown that in standard adaptation tasks, cognitive strategies operate alongside implicit learning. We reasoned that incomplete learning in adaptation tasks may primarily reflect a speed-accuracy tradeoff on time-consuming motor planning. Across three experiments, we find evidence supporting this hypothesis, showing that hastened motor planning may primarily lead to under-compensation. When an obligatory waiting period was administered before movement start, participants were able to fully counteract imposed perturbations (Experiment 1). Inserting the same delay between trials – rather than during movement planning – did not induce full compensation, suggesting that the motor planning interval influences the learning asymptote (Experiment 2). In the last experiment (Experiment 3), we asked participants to continuously report their movement intent. We show that emphasizing explicit re-aiming strategies (and concomitantly increasing planning time) also lead to complete asymptotic learning. Findings from all experiments support the hypothesis that incomplete adaptation is, in part, the result of an intrinsic speed-accuracy tradeoff, perhaps related to cognitive strategies that require parametric attentional reorienting from the visual target to the goal.

scholarly journals Prolonged reaction times help to eliminate residual errors in visuomotor adaptation

2019 ◽  
Author(s):  
Lisa Langsdorf ◽  
Jana Maresch ◽  
Mathias Hegele ◽  
Samuel D. McDougle ◽  
Raphael Schween
Keyword(s):  
Cognitive Strategies ◽  
Motor Planning ◽  
Reaction Times ◽  
Visuomotor Adaptation ◽  
Movement Planning ◽  
Planning Time ◽  
Trade Off ◽  
Full Compensation ◽  
Speed Accuracy ◽  
Residual Errors

AbstractOne persistent curiosity in visuomotor adaptation tasks is that participants often do not reach maximal performance. This incomplete asymptote has been explained as a consequence of obligatory computations within the implicit adaptation system, such as an equilibrium between learning and forgetting. A body of recent work has shown that in standard adaptation tasks, cognitive strategies operate alongside implicit learning. We reasoned that incomplete learning in adaptation tasks may primarily reflect a speed-accuracy trade-off on time-consuming motor planning. Across three experiments, we find evidence supporting this hypothesis, showing that hastened motor planning may primarily lead to under-compensation. When an obligatory waiting period was administered before movement start, participants were able to fully counteract imposed perturbations (experiment 1). Inserting the same delay between trials - rather than during movement planning - did not induce full compensation, suggesting that the motor planning interval predicts the learning asymptote (experiment 2). In the last experiment, we asked participants to continuously report their movement intent. We show that emphasizing explicit re-aiming strategies (and concomitantly increasing planning time) also lead to complete asymptotic learning. Findings from all experiments support the hypothesis that incomplete adaptation is, in part, the result of an intrinsic speed-accuracy trade-off, perhaps related to cognitive strategies that require parametric attentional reorienting from the visual target to the goal.

Influence of Viscous Loads on Motor Planning

2007 ◽  
Vol 98 (2) ◽  
pp. 870-877 ◽  
Author(s):  
Kurt A. Thoroughman ◽  
Wei Wang ◽  
Dimitre N. Tomov
Keyword(s):  
Force Field ◽  
Human Behavior ◽  
Motor Planning ◽  
Movement Planning ◽  
Viscous Force ◽  
Learned Behavior ◽  
Viscous Forces ◽  
Minimum Jerk ◽  
Human Arm ◽  
Minimum Torque

Here we computationally investigate how encumbering the hand could alter predictions made by the minimum torque change (MTC) and minimum endpoint variance hypotheses (MEPV) of movement planning. After minutes of training, people have made arm trajectories in a robot-generated viscous force field that were similar to previous baseline trajectories without the force field. We simulate the human arm interacting with this viscous load. We found that the viscous forces clearly differentiated MTC and MEPV predictions from both minimum-jerk predictions and from human behavior. We conclude that learned behavior in the viscous environment could arise from minimizing kinematic costs but could not arise from a minimization of either torque change or endpoint variance.

scholarly journals Separable neuronal contributions to covertly attended locations and movement goals in macaque frontal cortex

2021 ◽  
Vol 7 (14) ◽  
pp. eabe0716
Author(s):  
Adam Messinger ◽  
Rossella Cirillo ◽  
Steven P. Wise ◽  
Aldo Genovesio
Keyword(s):  
Cognitive Process ◽  
Motor Planning ◽  
Movement Planning ◽  
Covert Attention ◽  
Endogenous Attention ◽  
Dual Purpose ◽  
Flexible Control ◽  
Neuronal Populations ◽  
Motor Intention ◽  
Symbolic Cues

We investigated the spatial representation of covert attention and movement planning in monkeys performing a task that used symbolic cues to decouple the locus of covert attention from the motor target. In the three frontal areas studied, most spatially tuned neurons reflected either where attention was allocated or the planned saccade. Neurons modulated by both covert attention and the motor plan were in the minority. Such dual-purpose neurons were especially rare in premotor and prefrontal cortex but were more common just rostral to the arcuate sulcus. The existence of neurons that indicate where the monkey was attending but not its movement goal runs counter to the idea that the control of spatial attention is entirely reliant on the neuronal circuits underlying motor planning. Rather, the presence of separate neuronal populations for each cognitive process suggests that endogenous attention is under flexible control and can be dissociated from motor intention.

scholarly journals Optimal use of limb mechanics distributes control during bimanual tasks

2018 ◽  
Vol 119 (3) ◽  
pp. 921-932 ◽  
Author(s):  
David Córdova Bulens ◽  
Frédéric Crevecoeur ◽  
Jean-Louis Thonnard ◽  
Philippe Lefèvre
Keyword(s):  
Nervous System ◽  
Feedback Control ◽  
Biomechanical Model ◽  
Movement Planning ◽  
Optimal Feedback Control ◽  
Joint Configuration ◽  
Bimanual Task ◽  
Target Force ◽  
Biomechanical Constraints ◽  
Bimanual Tasks

Bimanual tasks involve the coordination of both arms, which often offers redundancy in the ways a task can be completed. The distribution of control across limbs is often considered from the perspective of handedness. In this context, although there are differences across dominant and nondominant arms during reaching control ( Sainburg 2002 ), previous studies have shown that the brain tends to favor the dominant arm when performing bimanual tasks ( Salimpour and Shadmehr 2014 ). However, biomechanical factors known to influence planning and control in unimanual tasks may also generate limb asymmetries in force generation, but their influence on bimanual control has remained unexplored. We investigated this issue in a series of experiments in which participants were instructed to generate a 20-N force with both arms, with or without perturbation of the target force during the trial. We modeled the task in the framework of optimal feedback control of a two-link model with six human-like muscles groups. The biomechanical model predicted a differential contribution of each arm dependent on the orientation of the target force and joint configuration that was quantitatively matched by the participants’ behavior, regardless of handedness. Responses to visual perturbations were strongly influenced by the perturbation direction, such that online corrections also reflected an optimal use of limb biomechanics. These results show that the nervous system takes biomechanical constraints into account when optimizing the distribution of forces generated across limbs during both movement planning and feedback control of a bimanual task. NEW & NOTEWORTHY Here, we studied a bimanual force production task to examine the effects of biomechanical constraints on the distribution of control across limbs. Our findings show that the central nervous system optimizes the distribution of force across the two arms according to the joint configuration of the upper limbs. We further show that the underlying mechanisms influence both movement planning and online corrective responses to sudden changes in the target force.

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