Neuroscience › Cognitive Neuroscience

Motor Control and Adaptation

Works Count: 31182

Wikipedia

Description

This cluster of papers explores the computational principles, neural basis, and learning mechanisms underlying motor control, sensorimotor learning, feedback control, and the role of structures such as the cerebellum in motor skill acquisition. It delves into topics like muscle synergies, visuomotor integration, implicit learning, and neuroplasticity in the context of motor control.

Keywords

Motor Control; Sensorimotor Learning; Feedback Control; Neural Basis; Motor Skill; Cerebellum; Muscle Synergies; Visuomotor Integration; Implicit Learning; Neuroplasticity

Computational principles of movement neuroscience

2000-11-01

Daniel M. Wolpert , Zoubin Ghahramani

Neural, mechanical, and geometric factors subserving arm posture in humans

1985-10-01

FA Mussa-Ivaldi , N. Hogan , Emilio Bizzi

When the hand is displaced from an equilibrium posture by an external disturbance, a force is generated to restore the original position. We developed a new experimental method to measure … When the hand is displaced from an equilibrium posture by an external disturbance, a force is generated to restore the original position. We developed a new experimental method to measure and represent the field of elastic forces associated with posture of the hand in the horizontal plane. While subjects maintained a given posture, small displacements of the hand along different directions were delivered by torque motors. The hand was held in the displaced positions and, at that time, we measured the corresponding restoring forces before the onset of any voluntary reaction. The stiffness in the vicinity of the hand equilibrium position was estimated by analyzing the force and displacement vectors. We chose to represent the stiffness both numerically, as a matrix, and graphically, as an ellipse characterized by three parameters: magnitude (the area), shape (the ratio of axis) and orientation (direction of the major axis). The latter representation captures the main geometrical features of the elastic force field associated with posture. We also evaluated the conservative and nonconservative components of this elastic force field. We found that the former were much larger than the latter and concluded that the behavior of the neuromuscular system of the multiarticular arm is predominantly spring-like. Our data indicated that the shape and orientation of the stiffness were invariant over subjects and over time. We also investigated the ability of our subjects to produce voluntary and adaptive changes in the stiffness. Our findings indicated that, when a disturbance acting along a fixed and predictable direction was imposed, the magnitude of the stiffness was increased but only minor changes in shape and orientation occurred. Taken together, all of these experiments represent a step toward the understanding of the interactions between geometrical and neural factors involved in maintaining hand posture and its interactions with the environment.

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The coordination of arm movements: an experimentally confirmed mathematical model

1985-07-01

Tamar Flash , N. Hogan

This paper presents studies of the coordination of voluntary human arm movements. A mathematical model is formulated which is shown to predict both the qualitative features and the quantitative details … This paper presents studies of the coordination of voluntary human arm movements. A mathematical model is formulated which is shown to predict both the qualitative features and the quantitative details observed experimentally in planar, multijoint arm movements. Coordination is modeled mathematically by defining an objective function, a measure of performance for any possible movement. The unique trajectory which yields the best performance is determined using dynamic optimization theory. In the work presented here, the objective function is the square of the magnitude of jerk (rate of change of acceleration) of the hand integrated over the entire movement. This is equivalent to assuming that a major goal of motor coordination is the production of the smoothest possible movement of the hand. Experimental observations of human subjects performing voluntary unconstrained movements in a horizontal plane are presented. They confirm the following predictions of the mathematical model: unconstrained point-to-point motions are approximately straight with bell-shaped tangential velocity profiles; curved motions (through an intermediate point or around an obstacle) have portions of low curvature joined by portions of high curvature; at points of high curvature, the tangential velocity is reduced; the durations of the low-curvature portions are approximately equal. The theoretical analysis is based solely on the kinematics of movement independent of the dynamics of the musculoskeletal system and is successful only when formulated in terms of the motion of the hand in extracorporal space. The implications with respect to movement organization are discussed.

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An organizing principle for a class of voluntary movements

1984-11-01

N. Hogan

This paper presents a mathematical model which predicts both the major qualitative features and, within experimental error, the quantitative details of a class of perturbed and unperturbed large-amplitude, voluntary movements … This paper presents a mathematical model which predicts both the major qualitative features and, within experimental error, the quantitative details of a class of perturbed and unperturbed large-amplitude, voluntary movements performed at intermediate speed by primates. A feature of the mathematical model is that a concise description of the behavioral organization of the movement has been formulated which is separate and distinct from the description of the dynamics of movement execution. Based on observations of voluntary movements in primates, the organization has been described as though the goal were to make the smoothest movement possible under the circumstances, i.e., to minimize the accelerative transients. This has been formalized by using dynamic optimization theory to determine the movement which minimizes the rate of change of acceleration (jerk) of the limb. Based on observations of muscle mechanics, the concept of a "virtual position" determined by the active states of the muscles is rigorously defined as one of the mechanical consequences of the neural commands to the muscles. This provides insight into the mechanics of perturbed and unperturbed movements and is a useful aid in the separation of the descriptions of movement organization and movement execution.

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On the relations between the direction of two-dimensional arm movements and cell discharge in primate motor cortex

1982-11-01

A. P. Georgopoulos , JF Kalaska , Roberto Caminiti +1 more

The activity of single cells in the motor cortex was recorded while monkeys made arm movements in eight directions (at 45 degrees intervals) in a two-dimensional apparatus. These movements started … The activity of single cells in the motor cortex was recorded while monkeys made arm movements in eight directions (at 45 degrees intervals) in a two-dimensional apparatus. These movements started from the same point and were of the same amplitude. The activity of 606 cells related to proximal arm movements was examined in the task; 323 of the 606 cells were active in that task and were studied in detail. The frequency of discharge of 241 of the 323 cells (74.6%) varied in an orderly fashion with the direction of movement. Discharge was most intense with movements in a preferred direction and was reduced gradually when movements were made in directions farther and farther away from the preferred one. This resulted in a bell-shaped directional tuning curve. These relations were observed for cell discharge during the reaction time, the movement time, and the period that preceded the earliest changes in the electromyographic activity (approximately 80 msec before movement onset). In about 75% of the 241 directionally tuned cells, the frequency of discharge, D, was a sinusoidal function of the direction of movement, theta: D = b0 + b1 sin theta + b2cos theta, or, in terms of the preferred direction, theta 0: D = b0 + c1cos (theta - theta0), where b0, b1, b2, and c1 are regression coefficients. Preferred directions differed for different cells so that the tuning curves partially overlapped. The orderly variation of cell discharge with the direction of movement and the fact that cells related to only one of the eight directions of movement tested were rarely observed indicate that movements in a particular direction are not subserved by motor cortical cells uniquely related to that movement. It is suggested, instead, that a movement trajectory in a desired direction might be generated by the cooperation of cells with overlapping tuning curves. The nature of this hypothetical population code for movement direction remains to be elucidated.

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Adaptive representation of dynamics during learning of a motor task

1994-05-01

Reza Shadmehr , FA Mussa-Ivaldi

We investigated how the CNS learns to control movements in different dynamical conditions, and how this learned behavior is represented. In particular, we considered the task of making reaching movements … We investigated how the CNS learns to control movements in different dynamical conditions, and how this learned behavior is represented. In particular, we considered the task of making reaching movements in the presence of externally imposed forces from a mechanical environment. This environment was a force field produced by a robot manipulandum, and the subjects made reaching movements while holding the end-effector of this manipulandum. Since the force field significantly changed the dynamics of the task, subjects' initial movements in the force field were grossly distorted compared to their movements in free space. However, with practice, hand trajectories in the force field converged to a path very similar to that observed in free space. This indicated that for reaching movements, there was a kinematic plan independent of dynamical conditions. The recovery of performance within the changed mechanical environment is motor adaptation. In order to investigate the mechanism underlying this adaptation, we considered the response to the sudden removal of the field after a training phase. The resulting trajectories, named aftereffects, were approximately mirror images of those that were observed when the subjects were initially exposed to the field. This suggested that the motor controller was gradually composing a model of the force field, a model that the nervous system used to predict and compensate for the forces imposed by the environment. In order to explore the structure of the model, we investigated whether adaptation to a force field, as presented in a small region, led to aftereffects in other regions of the workspace. We found that indeed there were aftereffects in workspace regions where no exposure to the field had taken place; that is, there was transfer beyond the boundary of the training data. This observation rules out the hypothesis that the subject's model of the force field was constructed as a narrow association between visited states and experienced forces; that is, adaptation was not via composition of a look-up table. In contrast, subjects modeled the force field by a combination of computational elements whose output was broadly tuned across the motor state space. These elements formed a model that extrapolated to outside the training region in a coordinate system similar to that of the joints and muscles rather than end-point forces. This geometric property suggests that the elements of the adaptive process represent dynamics of a motor task in terms of the intrinsic coordinate system of the sensors and actuators.

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Signal-dependent noise determines motor planning

1998-08-01

Christopher M. Harris , Daniel M. Wolpert

A theoretical model of phase transitions in human hand movements

1985-02-01

Hermann Haken , J. A. Scott Kelso , H. Bunz

Grasping objects: the cortical mechanisms of visuomotor transformation

1995-07-01

Marc Jeannerod , Michael A. Arbib , Giacomo Rizzolatti +1 more

A Closed-Loop Theory of Motor Learning

1971-06-01

Jack A. Adams

Following a discussion of the meaning of the term "skills" and a review of historical influences on their learning, a closed-loop theory for learning simple movements is presented. Empirical generalizations … Following a discussion of the meaning of the term "skills" and a review of historical influences on their learning, a closed-loop theory for learning simple movements is presented. Empirical generalizations from the literature are stated, and the theory is used to explain them. The generalizations are of 2 classes: learning through the application of knowledge of results, and the effects of withdrawing knowledge of results.

Increased Cortical Representation of the Fingers of the Left Hand in String Players

1995-10-13

Thomas Elbert , Christo Pantev , Christian Wienbruch +2 more

Magnetic source imaging revealed that the cortical representation of the digits of the left hand of string players was larger than that in controls. The effect was smallest for the … Magnetic source imaging revealed that the cortical representation of the digits of the left hand of string players was larger than that in controls. The effect was smallest for the left thumb, and no such differences were observed for the representations of the right hand digits. The amount of cortical reorganization in the representation of the fingering digits was correlated with the age at which the person had begun to play. These results suggest that the representation of different parts of the body in the primary somatosensory cortex of humans depends on use and changes to conform to the current needs and experiences of the individual.

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Optimal feedback control as a theory of motor coordination

2002-10-28

Emanuel Todorov , Michael I. Jordan

Bayesian integration in sensorimotor learning

2004-01-01

Konrad P. Körding , Daniel M. Wolpert

Once More on the Equilibrium-Point Hypothesis (λ Model) for Motor Control

1986-03-01

Anatol G. Feldman

The equilibrium control hypothesis (λ model) is considered with special reference to the following concepts: (a) the length-force invariant characteristic (IC) of the muscle together with central and reflex systems … The equilibrium control hypothesis (λ model) is considered with special reference to the following concepts: (a) the length-force invariant characteristic (IC) of the muscle together with central and reflex systems subserving its activity; (b) the tonic stretch reflex threshold (λ) as an independent measure of central commands descending to alpha and gamma motoneurons; (c) the equilibrium point, defined in terms of λ, IC and static load characteristics, which is associated with the notion that posture and movement are controlled by a single mechanism; and (d) the muscle activation area (a reformulation of the "size principle")— the area of kinematic and command variables in which a rank-ordered recruitment of motor units takes place. The model is used for the interpretation of various motor phenomena, particularly electromyographic patterns. The stretch reflex in the λ model has no mechanism to follow-up a certain muscle length prescribed by central commands. Rather, its task is to bring the system to an equilibrium, load-dependent position. Another currently popular version defines the equilibrium point concept in terms of alpha motoneuron activity alone (the α model). Although the model imitates (as does the λ model) spring-like properties of motor performance, it nevertheless is inconsistent with a substantial data base on intact motor control. An analysis of α models, including their treatment of motor performance in deafferented animals, reveals that they suffer from grave shortcomings. It is concluded that parameterization of the stretch reflex is a basis for intact motor control. Muscle deafferentation impairs this graceful mechanism though it does not remove the possibility of movement.

Posterior parietal cortex in rhesus monkey: II. Evidence for segregated corticocortical networks linking sensory and limbic areas with the frontal lobe

1989-09-22

Carmen Cavada , Patricia S. Goldman‐Rakic

Abstract We have examined the circuitry connecting the posterior parietal cortex with the frontal lobe of rhesus monkeys. HRP‐WGA and tritiated amino acids were injected into subdivisions 7m, 7a, 7b, … Abstract We have examined the circuitry connecting the posterior parietal cortex with the frontal lobe of rhesus monkeys. HRP‐WGA and tritiated amino acids were injected into subdivisions 7m, 7a, 7b, and 7ip of the posterior parietal cortex, and anterograde and retrograde label was recorded within the frontal motor and association cortices. Our main finding is that each subdivision of parietal cortex is connected with a unique set of frontal areas. Thus, area 7m, on the medial parietal surface, is interconnected with the dorsal premotor cortex and the supplementary motor area, including the supplementary eye field. Within the prefrontal cortex, area 7m's connections are with the rostral sector of the frontal eye field (FEF), the dorsal bank of the principal sulcus, and the anterior bank of the inferior arcuate sulcus (Walker's area 45). In contrast, area 7a, on the posterior parietal convexity, is not linked with premotor regions but is heavily interconnected with the rostral FEF in the anterior bank of the superior arcuate sulcus, the dorsolateral prefrontal convexity, the rostral orbitofrontal cortex, area 45, and the fundus and adjacent cortex of the dorsal and ventral banks of the principal sulcus. Area 7b, in the anterior part of the posterior parietal lobule, is interconnected with still a different set of frontal areas, which include the ventral premotor cortex and supplementary motor area, area 45, and the external part of the ventral bank of the principal sulcus. The prominent connections of area 7ip, in the posterior bank of the intraparietal sulcus, are with the supplementary eye field and restricted portions of the ventral premotor cortex, with a wide area of the FEF that includes both its rostral and caudal sectors, and with area 45. All frontoparietal connections are reciprocal, and although they are most prominent within a hemisphere, notable interhemispheric connections are also present. These findings provide a basis for a parcellation of the classically considered association cortex of the frontal lobe, particularly the cortex of the principal sulcus, into sectors defined by their specific connections with the posterior parietal subdivisions. Moreover, the present findings, together with those of a companion study (Cavada and Goldman‐Rakic): J. Comp. Neurol . This issue have allowed us to establish multiple linkages between frontal areas and specific limbic and sensory cortices through the posterior parietal cortex. The net‐works thus defined may form part of the neural substrate of parallel distrib‐uted processing in the cerebral cortex.

Motor-output variability: A theory for the accuracy of rapid motor acts.

1979-09-01

Richard A. Schmidt , Howard N. Zelaznik , Brian Hawkins +2 more

Theoretical accounts of the speed-accuracy trade-off in rapid movement have usually focused on within-moveme nt error detection and correction, and have consistently ignored the possibility that motor-output variability might be … Theoretical accounts of the speed-accuracy trade-off in rapid movement have usually focused on within-moveme nt error detection and correction, and have consistently ignored the possibility that motor-output variability might be predictably related to movement amplitude and movement time. This article presents a theory of motor-output variability that accounts for the relationship among the movement amplitude, movement time, the mass to be moved, and the resulting movement error. Predictions are derived from physical principles; empirical evidence supporting the principles is presented for three movement paradigms (single-aiming responses, reciprocal movements, and rapid-timing tasks); and the theory and data are discussed in terms of past theoretical accounts and future research directions. Examining the current level of understanding about the production and control of motor responses, many would no doubt be tempted to say that we have not come very far since the early writings of Woodworth (1899) and Hollingworth (1909). These writers were concerned with the basic laws of limb movements (analogous, perhaps to the basic laws of motion that were the cornerstone of physics) that denned the relationship between the simplest aspects of motor

Movement, posture and equilibrium: Interaction and coordination

1992-01-01

Jean Massion

Supplementary motor area structure and function: Review and hypotheses

1985-12-01

Gary Goldberg

Abstract Though its existence has been known for well over 30 years, only recently has the supplementary motor area (SMA) and its role in the cortical organization of movement come … Abstract Though its existence has been known for well over 30 years, only recently has the supplementary motor area (SMA) and its role in the cortical organization of movement come to be examined in detail by neuroscientists. Evidence from a wide variety of investigational perspectives is reviewed in an attempt to synthesize a conceptual framework for understanding SMA function. It is suggested that the SMA has an important role to play in the intentional process whereby internal context influences the elaboration of action. It may be viewed as phylogenetically older motor cortex, derived from anterior cingulate periarchicortical limbic cortex, which, as a key part of a medial premotor system, is crucial in the “programming” and fluent execution of extended action sequences which are “projectional” in that they rely on model-based prediction. This medial system can be distinguished from a lateral premotor system postulated to have evolved over phylogeny from a different neural source. An anatomico-physiologic model of the medial premotor system is proposed which embodies the principles of cyclicity and reentrance in the process of selecting those neural components to become active in conjunction with the performance of a particular action. The postulated dynamic action of this model in the microgenesis of a discrete action is outlined. It is concluded that although there is a great deal to be learned about the SMA, a convergence of current evidence can be identified. Such evidence suggests that the SMA plays an important role in the development of the intention-to-act and the specification and elaboration of action through its mediation between medial limbic cortex and primary motor cortex.

THE CONTRIBUTION OF MUSCLE AFFERENTS TO KESLESTHESIA SHOWN BY VIBRATION INDUCED ILLUSIONSOF MOVEMENT AND BY THE EFFECTS OF PARALYSING JOINT AFFERENTS

1972-01-01

Guy M. Goodwin , D.I. McCloskey , P. B. C. Matthews

Journal Article THE CONTRIBUTION OF MUSCLE AFFERENTS TO KESLESTHESIA SHOWN BY VIBRATION INDUCED ILLUSIONSOF MOVEMENT AND BY THE EFFECTS OF PARALYSING JOINT AFFERENTS Get access G. M. GOODWIN, G. M. … Journal Article THE CONTRIBUTION OF MUSCLE AFFERENTS TO KESLESTHESIA SHOWN BY VIBRATION INDUCED ILLUSIONSOF MOVEMENT AND BY THE EFFECTS OF PARALYSING JOINT AFFERENTS Get access G. M. GOODWIN, G. M. GOODWIN University Laboratory of PhysiologyOxford Search for other works by this author on: Oxford Academic PubMed Google Scholar D. I. McCLOSKEY, D. I. McCLOSKEY University Laboratory of PhysiologyOxford Search for other works by this author on: Oxford Academic PubMed Google Scholar P. B. C. MATTHEWS P. B. C. MATTHEWS University Laboratory of PhysiologyOxford Search for other works by this author on: Oxford Academic PubMed Google Scholar Brain, Volume 95, Issue 4, 1972, Pages 705–748, https://doi.org/10.1093/brain/95.4.705 Published: 01 January 1972 Article history Published: 01 January 1972 Received: 16 February 1972

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Knowledge of results and motor learning: A review and critical reappraisal.

1984-01-01

Alan W. Salmoni , Richard A. Schmidt , Charles B. Walter

Interacting Adaptive Processes with Different Timescales Underlie Short-Term Motor Learning

2006-05-15

Maurice A. Smith , Ali Ghazizadeh , Reza Shadmehr

Multiple processes may contribute to motor skill acquisition, but it is thought that many of these processes require sleep or the passage of long periods of time ranging from several … Multiple processes may contribute to motor skill acquisition, but it is thought that many of these processes require sleep or the passage of long periods of time ranging from several hours to many days or weeks. Here we demonstrate that within a timescale of minutes, two distinct fast-acting processes drive motor adaptation. One process responds weakly to error but retains information well, whereas the other responds strongly but has poor retention. This two-state learning system makes the surprising prediction of spontaneous recovery (or adaptation rebound) if error feedback is clamped at zero following an adaptation-extinction training episode. We used a novel paradigm to experimentally confirm this prediction in human motor learning of reaching, and we show that the interaction between the learning processes in this simple two-state system provides a unifying explanation for several different, apparently unrelated, phenomena in motor adaptation including savings, anterograde interference, spontaneous recovery, and rapid unlearning. Our results suggest that motor adaptation depends on at least two distinct neural systems that have different sensitivity to error and retain information at different rates.

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Optimality principles in sensorimotor control

2004-08-26

Emanuel Todorov

An Internal Model for Sensorimotor Integration

1995-09-29

Daniel M. Wolpert , Zoubin Ghahramani , Michael I. Jordan

On the basis of computational studies it has been proposed that the central nervous system internally simulates the dynamic behavior of the motor system in planning, control, and learning; the … On the basis of computational studies it has been proposed that the central nervous system internally simulates the dynamic behavior of the motor system in planning, control, and learning; the existence and use of such an internal model is still under debate. A sensorimotor integration task was investigated in which participants estimated the location of one of their hands at the end of movements made in the dark and under externally imposed forces. The temporal propagation of errors in this task was analyzed within the theoretical framework of optimal state estimation. These results provide direct support for the existence of an internal model.

The acquisition of skilled motor performance: Fast and slow experience-driven changes in primary motor cortex

1998-02-03

Avi Karni , Gundela Meyer , Christine Rey-Hipolito +4 more

Behavioral and neurophysiological studies suggest that skill learning can be mediated by discrete, experience-driven changes within specific neural representations subserving the performance of the trained task. We have shown that … Behavioral and neurophysiological studies suggest that skill learning can be mediated by discrete, experience-driven changes within specific neural representations subserving the performance of the trained task. We have shown that a few minutes of daily practice on a sequential finger opposition task induced large, incremental performance gains over a few weeks of training. These gains did not generalize to the contralateral hand nor to a matched sequence of identical component movements, suggesting that a lateralized representation of the learned sequence of movements evolved through practice. This interpretation was supported by functional MRI data showing that a more extensive representation of the trained sequence emerged in primary motor cortex after 3 weeks of training. The imaging data, however, also indicated important changes occurring in primary motor cortex during the initial scanning sessions, which we proposed may reflect the setting up of a task-specific motor processing routine. Here we provide behavioral and functional MRI data on experience-dependent changes induced by a limited amount of repetitions within the first imaging session. We show that this limited training experience can be sufficient to trigger performance gains that require time to become evident. We propose that skilled motor performance is acquired in several stages: “fast” learning, an initial, within-session improvement phase, followed by a period of consolidation of several hours duration, and then “slow” learning, consisting of delayed, incremental gains in performance emerging after continued practice. This time course may reflect basic mechanisms of neuronal plasticity in the adult brain that subserve the acquisition and retention of many different skills.

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A schema theory of discrete motor skill learning.

1975-07-01

Richard A. Schmidt

Formation and control of optimal trajectory in human multijoint arm movement

1989-06-01

Y. Uno , Mitsuo Kawato , Ryoji Suzuki

The Timing of Natural Prehension Movements

1984-09-01

Marc Jeannerod

Prehension movements were studied by film in 7 adult subjects. Transportation of the hand to the target-object location had features very similar to any aiming arm movement, that is, it … Prehension movements were studied by film in 7 adult subjects. Transportation of the hand to the target-object location had features very similar to any aiming arm movement, that is, it involved a fast-velocity initial phase and a low-velocity final phase. The peak velocity of the movement was highly correlated with its amplitude, although total movement duration tended to remain invariant when target distance was changed. The low-velocity phase consistently began after about 75 % of movement time had elapsed. This ratio was maintained for different movement amplitudes. Formation of the finger grip occurred during hand transportation. Fingers were first stretched and then began to close in anticipation to contact with the object. The onset of the closure phase was highly correlated to the beginning of the low velocity phase of transportation. This pattern for both transportation and finger grip formation was maintained in conditions whether visual feedback from the moving limb was present or not. Implications of these findings for the central programming of multisegmental movements are discussed.

Challenge Point: A Framework for Conceptualizing the Effects of Various Practice Conditions in Motor Learning

2004-07-01

Mark A. Guadagnoli , Timothy D. Lee

The authors describe the effects of practice conditions in motor learning (e.g., contextual interference, knowledge of results) within the constraints of 2 experimental variables: skill level and task difficulty. They … The authors describe the effects of practice conditions in motor learning (e.g., contextual interference, knowledge of results) within the constraints of 2 experimental variables: skill level and task difficulty. They use a research framework to conceptualize the interaction of those variables on the basis of concepts from information theory and information processing. The fundamental idea is that motor tasks represent different challenges for performers of different abilities. The authors propose that learning is related to the information arising from performance, which should be optimized along functions relating the difficulty of the task to the skill level of the performer. Specific testable hypotheses arising from the framework are also described.

Forward Models for Physiological Motor Control

1996-11-01

R. Chris Miall , Daniel M. Wolpert

Forward modeling allows feedback control for fast reaching movements

2000-11-01

Michel Desmurget , Scott T. Grafton

Delays in sensorimotor loops have led to the proposal that reaching movements are primarily under pre-programmed control and that sensory feedback loops exert an influence only at the very end … Delays in sensorimotor loops have led to the proposal that reaching movements are primarily under pre-programmed control and that sensory feedback loops exert an influence only at the very end of a trajectory. The present review challenges this view. Although behavioral data suggest that a motor plan is assembled prior to the onset of movement, more recent studies have indicated that this initial plan does not unfold unaltered, but is updated continuously by internal feedback loops. These loops rely on a forward model that integrates the sensory inflow and motor outflow to evaluate the consequence of the motor commands sent to a limb, such as the arm. In such a model, the probable position and velocity of an effector can be estimated with negligible delays and even predicted in advance, thus making feedback strategies possible for fast reaching movements. The parietal lobe and cerebellum appear to play a crucial role in this process. The ability of the motor system to estimate the future state of the limb might be an evolutionary substrate for mental operations that require an estimate of sequelae in the immediate future.

Multiple paired forward and inverse models for motor control

1998-10-01

Daniel M. Wolpert , Mitsuo Kawato

A computational neuroanatomy for motor control

2008-02-04

Reza Shadmehr , John W. Krakauer

Internal models for motor control and trajectory planning

1999-12-01

Mitsuo Kawato

Phase transitions and critical behavior in human bimanual coordination

1984-06-01

J. A. Scott Kelso

Conditions that give rise to phase shifts among the limbs when an animal changes gait are poorly understood. Often a “switch mechanism” is invoked that has a neural basis which … Conditions that give rise to phase shifts among the limbs when an animal changes gait are poorly understood. Often a “switch mechanism” is invoked that has a neural basis which remains speculative. Abrupt phase transitions also occur between the two hands in humans when movement-cycling frequency is continuously increased. The asymmetrical out-of-phase mode shifts suddenly to a symmetrical in-phase mode involving simultaneous activation of homologous muscle groups. The boundary between the two coordinative states is indexed by a dimensionless critical number, which remains constant regardless of whether the hands move freely or are subject to resistive loading. Coordinated shifts appear to arise because of continuous scaling influences that render the existing mode unstable. Then, at a critical point, bifurcation occurs and a new stable (and perhaps energetically more efficient) mode emerges.

Actions and habits: the development of behavioural autonomy

1985-02-13

Anthony Dickinson

The study of animal behaviour has been dominated by two general models. According to the mechanistic stimulus-response model, a particular behaviour is either an innate or an acquired habit which … The study of animal behaviour has been dominated by two general models. According to the mechanistic stimulus-response model, a particular behaviour is either an innate or an acquired habit which is simply triggered by the appropriate stimulus. By contrast, the teleological model argues that, at least, some activities are purposive actions controlled by the current value of their goals through knowledge about the instrumental relations between the actions and their consequences. The type of control over any particular behaviour can be determined by a goal revaluation procedure. If the anim al’s performance changes appropriately following an alteration in the value of the goal or reward without further experience of the instrumental relationship, the behaviour should be regarded as a purposive action. On the other hand, the stimulus-response model is more appropriate for an activity whose performance is autonomous of the current value of the goal. By using this assay, we have found that a simple food-rewarded activity is sensitive to reward devaluation in rats following limited but not extended training. The development of this behavioural autonomy with extended training appears to depend not upon the am ount of training per se, but rather upon the fact that the animal no longer experiences the correlation between variations in performance and variations in the associated consequences during overtraining. In agreement with this idea, limited exposure to an instrumental relationship that arranges a low correlation between performance and reward rates also favours the development of behavioural autonomy. Thus, the same activity can be either an action or a habit depending upon the type of training it has received.

Two visual systems re-viewed

2007-11-09

A. David Milner , Melvyn A. Goodale

The uncontrolled manifold concept: identifying control variables for a functional task

1999-05-14

J. P. Scholz , Gregor Schöner

The organization of human postural movements: A formal basis and experimental synthesis

1985-03-01

Lewis M. Nashner , Gin McCollum

Abstract A scheme for understanding the organization of human postural movements is developed in the format of a position paper. The structural characteristics of the body and the geometry of … Abstract A scheme for understanding the organization of human postural movements is developed in the format of a position paper. The structural characteristics of the body and the geometry of muscular actions are incorporated into a three-dimensional graphical representation of human movement mechanics in the sagittal plane. A series of neural organizational hypotheses limit a theoretically infinite number of combinations of muscle contractions and associated movement trajectories for performing postural corrections: (1) Controls are organized to use the minimum number of muscles; (2) frequently performed movements are organized to require a minimum of neural decision-making. These hypotheses lead to the prediction that postural movements are composed of muscle contractile strategies derived from a limited set of distinct contractile patterns. The imposition of two mechanical constraints related to the configuration of support and to requirements for body stability with respect to gravity predict the conditions under which individual movement strategies will be deployed. A complementary organizational scheme for the senses is developed. We show that organization of postural movements into combinations of distinct strategies simplifies the interpretation of sensory inputs. The fine-tuning of movement strategies can be accomplished by breaking down the complex array of feedback information into a series of scalar quantities related to the parameters of the movement strategies. For example, the magnitude, aim, and curvature of the movement trajectory generated by an individual strategy can be adjusted independently. The second half of the report compares theoretical predictions with a series of actual experimental observations on normal subjects and patients with known sensory and motor disorders. Actual postural movements conform to theoretical predictions about the composition of individual movement strategies and the conditions under which each strategy is used. Observations on patients suggest how breakdowns in individual steps within the logical process of organization can lead to specific movement abnormalities. Discussion focuses on the areas needing further experimentation and on the implications of the proposed organizational scheme. We conclude that although our organizational scheme is not new in demonstrating the need for simplifying the neural control of movement, it is perhaps original in imposing discrete logical control upon a continuous mechanical system. The attraction of the scheme is that it provides a framework compatible with both mechanical and physiological information and amenable to experimental testing.

New Conceptualizations of Practice: Common Principles in Three Paradigms Suggest New Concepts for Training

1992-07-01

Richard A. Schmidt , Robert A. Bjork

We argue herein that typical training procedures are far from optimal. The goat of training in real-world settings is, or should be, to support two aspects of posttraining performance: (a) … We argue herein that typical training procedures are far from optimal. The goat of training in real-world settings is, or should be, to support two aspects of posttraining performance: (a) the level of performance in the long term and (b) the capability to transfer that training to related tasks and altered contexts. The implicit or explicit assumption of those persons responsible for training is that the procedures that enhance performance and speed improvement during training will necessarily achieve these two goals. However, a variety of experiments on motor and verbal learning indicate that this assumption is often incorrect. Manipulations that maximize performance during training can be detrimental in the long term; conversely, manipulations that degrade the speed of acquisition can support the long-term goals of training. The fact that there are parallel findings in the motor and verbal domains suggests that principles of considerable generality can be deduced to upgrade training procedures.

Optimality in human motor performance: Ideal control of rapid aimed movements.

1988-01-01

David E. Meyer , Richard A. Abrams , Sylvan Kornblum +2 more

A stochastic optimized-submovement model is proposed for Pitts' law, the classic logarithmic tradeoff between the duration and spatial precision of rapid aimed movements. According to the model, an aimed movement … A stochastic optimized-submovement model is proposed for Pitts' law, the classic logarithmic tradeoff between the duration and spatial precision of rapid aimed movements. According to the model, an aimed movement toward a specified target region involves a primary submovement and an optional secondary corrective submovement. The submovements are assumed to be programmed such that they minimize average total movement time while maintaining a high frequency of target hits. The programming process achieves this minimization by optimally adjusting the average magnitudes and durations of noisy neuromotor force pulses used to generate the submovements. Numerous results from the literature on human motor performance may be explained in these terms. Two new experiments on rapid wrist rotations yield additional support for the stochastic optimizedsubmovement model. Experiment 1 revealed that the mean durations of primary submovements and of secondary submovements, not just average total movement times, conform to a square-root approximation of Pitts' law derived from the model. Also, the spatial endpoints of primary submovements have standard deviations that increase linearly with average primary-submovement velocity, and the average primary-submovement velocity influences the relative frequencies of secondary submovements, as predicted by the model. During Experiment 2, these results were replicated and extended under conditions in which subjects made movements without concurrent visual feedback. This replication suggests that submovement optimization may be a pervasive property of movement production. The present conceptual framework provides insights into principles of motor performance, and it links the study of physical action to research on sensation, perception, and cognition, where psychologists have been concerned for some time about the degree to which mental processes incorporate rational and normative rules. An enduring issue in the study of the human mind concerns of mathematical probability theory and statistical decision thethe rationality and optimality of the mental processes that guide ory (e.g., see Edwards, 1961; Edwards, Lindman, & Savage,

Practice-related Changes in Human Brain Functional Anatomy during Nonmotor Learning

1994-01-01

Marcus E. Raichle , Julie A. Fiez , Tom O. Videen +4 more

Practice of a novel task leads to improved performance. The brain mechanisms associated with practice-induced improvement in performance are largely unknown. To address this question we have examined the functional … Practice of a novel task leads to improved performance. The brain mechanisms associated with practice-induced improvement in performance are largely unknown. To address this question we have examined the functional anatomy of the human brain with positron emission tomography (PET) during the naive and practiced performance of a simple verbal response selection task (saying an appropriate verb for a visually presented noun). As a control state, subjects were asked to repeat the visually presented nouns. Areas of the brain most active during naive performance (anterior cingulata, left prefrontal and left posterior temporal cortices, and the right cerebellar hemisphere), compared to repeating the visually presented nouns, were all significantly less active during practiced performance. These changes were accompanied by changes in the opposite direction in sylvian-insular cortex bilaterally and left medial extras-triate cortex. In effect, brief practice made the cortical circuitry used for verbal response selection indistinguishable from simple word repetition. Introduction of a novel list of words reversed the learning-related effects. These results indicate that two distinct circuits can be used for verbal response selection and normal subjects can change the brain circuits used during task performance following less than 15 min of practice. One critical factor in determining the circuitry used appears to be the degree to which a task is learned or automatic.

Intentional Maps in Posterior Parietal Cortex

2002-03-01

Richard A. Andersen , Christopher A. Buneo

▪ Abstract The posterior parietal cortex (PPC), historically believed to be a sensory structure, is now viewed as an area important for sensory-motor integration. Among its functions is the forming … ▪ Abstract The posterior parietal cortex (PPC), historically believed to be a sensory structure, is now viewed as an area important for sensory-motor integration. Among its functions is the forming of intentions, that is, high-level cognitive plans for movement. There is a map of intentions within the PPC, with different subregions dedicated to the planning of eye movements, reaching movements, and grasping movements. These areas appear to be specialized for the multisensory integration and coordinate transformations required to convert sensory input to motor output. In several subregions of the PPC, these operations are facilitated by the use of a common distributed space representation that is independent of both sensory input and motor output. Attention and learning effects are also evident in the PPC. However, these effects may be general to cortex and operate in the PPC in the context of sensory-motor transformations.

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Postural Hand Synergies for Tool Use

1998-12-01

Marco Santello , Martha Flanders , John F. Soechting

Subjects were asked to shape the right hand as if to grasp and use a large number of familiar objects. The chosen objects typically are held with a variety of … Subjects were asked to shape the right hand as if to grasp and use a large number of familiar objects. The chosen objects typically are held with a variety of grips, including "precision" and "power" grips. Static hand posture was measured by recording the angular position of 15 joint angles of the fingers and of the thumb. Although subjects adopted distinct hand shapes for the various objects, the joint angles of the digits did not vary independently. Principal components analysis showed that the first two components could account for >80% of the variance, implying a substantial reduction from the 15 degrees of freedom that were recorded. However, even though they were small, higher-order (more than three) principal components did not represent random variability but instead provided additional information about the object. These results suggest that the control of hand posture involves a few postural synergies, regulating the general shape of the hand, coupled with a finer control mechanism providing for small, subtle adjustments. Because the postural synergies did not coincide with grip taxonomies, the results suggest that hand posture may be regulated independently from the control of the contact forces that are used to grasp an object.

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Plasticity and Primary Motor Cortex

2000-03-01

Jerome N. Sanes , John P. Donoghue

One fundamental function of primary motor cortex (MI) is to control voluntary movements. Recent evidence suggests that this role emerges from distributed networks rather than discrete representations and that in … One fundamental function of primary motor cortex (MI) is to control voluntary movements. Recent evidence suggests that this role emerges from distributed networks rather than discrete representations and that in adult mammals these networks are capable of modification. Neuronal recordings and activation patterns revealed with neuroimaging methods have shown considerable plasticity of MI representations and cell properties following pathological or traumatic changes and in relation to everyday experience, including motor-skill learning and cognitive motor actions. The intrinsic horizontal neuronal connections in MI are a strong candidate substrate for map reorganization: They interconnect large regions of MI, they show activity-dependent plasticity, and they modify in association with skill learning. These findings suggest that MI cortex is not simply a static motor control structure. It also contains a dynamic substrate that participates in motor learning and possibly in cognitive events as well.

Error Correction, Sensory Prediction, and Adaptation in Motor Control

2010-06-01

Reza Shadmehr , Maurice A. Smith , John W. Krakauer

Motor control is the study of how organisms make accurate goal-directed movements. Here we consider two problems that the motor system must solve in order to achieve such control. The … Motor control is the study of how organisms make accurate goal-directed movements. Here we consider two problems that the motor system must solve in order to achieve such control. The first problem is that sensory feedback is noisy and delayed, which can make movements inaccurate and unstable. The second problem is that the relationship between a motor command and the movement it produces is variable, as the body and the environment can both change. A solution is to build adaptive internal models of the body and the world. The predictions of these internal models, called forward models because they transform motor commands into sensory consequences, can be used to both produce a lifetime of calibrated movements, and to improve the ability of the sensory system to estimate the state of the body and the world around it. Forward models are only useful if they produce unbiased predictions. Evidence shows that forward models remain calibrated through motor adaptation: learning driven by sensory prediction errors.

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Posterior parietal association cortex of the monkey: command functions for operations within extrapersonal space

1975-07-01

Vernon B. Mountcastle , James C. Lynch , A. P. Georgopoulos +2 more

Experiments were made on the posterior parietal association cortical areas 5 and in 17 hemispheres of 11 monkeys, 6 M. mulatta and 5 M. arctoides. The electrical signs of the … Experiments were made on the posterior parietal association cortical areas 5 and in 17 hemispheres of 11 monkeys, 6 M. mulatta and 5 M. arctoides. The electrical signs of the activity of single cortical cells were recorded with microelectrodes in waking animals as they carried out certain behavioral acts in response to a series of sensory cues. The behavioral paradigms were one for detection alone, and a second for detection plus projection of the arm to contact a stationary or moving target placed at arm's length. Of the 125 microelectrode penetrations made, 1,451 neurons were identified in terms of the correlation of their activity with the behavioral acts and their sensitivity or lack of it to sensory stimuli delivered passively; 180 were studied quantitatively. The locations of cortical neurons were identified in serial sections; 94 penetrations and 1,058 neurons were located with certainty. About two-thirds of the neurons of area 5 were activated by passive rotation of the limbs at their joints; of these, 82% were related to single, contralateral joints, 10% to two or more contralateral joints, 6% to ipsilateral, and 2% to joints on both sides of the body. A few of the latter were active during complex bodily postures. A large proportion of area 5 neurons were relatively insensitive to passive joint rotations, as compared with similar neurons of the postcentral gyrus, but were driven to high rates of discharge when the same joint was rotated during an active movement of the animal...

Constraints on the Development of Coordination

1986-01-01

Karl M. Newell

Measuring individual differences in implicit cognition: The implicit association test.

1998-01-01

Anthony G. Greenwald , Debbie E. McGhee , Jordan L. K. Schwartz

6.1464) is often used to predict people's behaviors.However, it has shown poor predictive ability potentially because of its typical scoring method (the D score), which is affected by the across-trial … 6.1464) is often used to predict people's behaviors.However, it has shown poor predictive ability potentially because of its typical scoring method (the D score), which is affected by the across-trial variability in the IAT data and might provide biased estimates of the construct.Linear Mixed-Effects Models (LMMs) can address this issue while providing a Rasch-like parametrization of accuracy and time responses.In this study, the predictive abilities of D scores and LMM estimates were compared.The LMMs estimates showed better predictive ability than the D score, and allowed for in-depth analyses at the stimulus level that helped in reducing the acrosstrial variability.Implications of the results and limitations of the study are discussed.

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Perceptual and Motor Skills

2014-02-07

C. H. Ammons

Motor prediction

2001-09-01

Daniel M. Wolpert , J. Randall Flanagan

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Responses of candidate intensity measures to different mental and motor load levels using upper limb exergames in typically developing children and adolescents

2025-06-25

Gaizka Goikoetxea-Sotelo , Livia Rätzo , Hubertus J. A. van Hedel | PLoS ONE

Background In (pediatric) neurorehabilitation, high-intensity therapy is well-recognized for enhancing rehabilitative outcomes. However, measures that consider the different aspects of therapy intensity are lacking. Therefore, a better understanding of how … Background In (pediatric) neurorehabilitation, high-intensity therapy is well-recognized for enhancing rehabilitative outcomes. However, measures that consider the different aspects of therapy intensity are lacking. Therefore, a better understanding of how to measure therapy intensity during upper-limb neurorehabilitation is needed. Objectives To investigate the response of heart rate variability (HRV), skin conductance (SC), activity counts and movement repetitions normalized for the maximal capacity (%ACmax and %MOVmax, respectively), and the NASA-TLX scale to different mental and motor intensity levels of two self-developed upper limb exergames in typically developing children. We also investigate the effects of age on the responses of the measures. Methods In this cross-sectional study, participants engaged in one mental and one motor exergame. For each exergame, they played three personalized intensity levels (“very easy,” “challenging,” and “very difficult”), each lasting three minutes. We analyzed the responses of all measures for each intensity level and exergame. Results 21 children and adolescents (9 females) aged 5.2 to 17.9 years participated in the study. HRV, %ACmax, and %MOVmax responded to increased motor intensity. SC did not respond to increases in mental or motor intensity levels. The NASA-TLX responded to increases in motor intensity levels but only partially to increases in mental intensity. Finally, age showed significant effects only on %MOVmax. Conclusion Changes in mental intensity were more challenging to capture than changes in motor intensity. As each measure responded to different aspects of therapy intensity, a combination of measures, e.g., HRV, %ACmax, and NASA-TLX effort, might be the best strategy for assessing therapy intensity multidimensionally. Although the measures hold considerable potential, future studies should determine the responses of the measures and their psychometric properties in the target group.

Disentangling acute motor deficits and adaptive responses evoked by the loss of cerebellar output

2025-06-25

Nirvik Sinha , Sharon Israely , Ora Ben Harosh +3 more | eLife

Patients with cerebellar damage experience various motor impairments, but the specific sequence of primary and compensatory processes that contribute to these deficits remains unclear. To clarify this, we reversibly blocked … Patients with cerebellar damage experience various motor impairments, but the specific sequence of primary and compensatory processes that contribute to these deficits remains unclear. To clarify this, we reversibly blocked cerebellar outflow in monkeys engaged in planar reaching tasks. This intervention led to a spatially selective reduction in hand velocity, primarily due to decreased muscle torque, especially in movements requiring high inter-joint torque coupling. When examining repeated reaches to the same target, we found that the reduced velocity resulted from both an immediate deficit and a gradually developing compensatory slowing to reduce passive inter-joint interactions. However, the slowed hand velocity did not account for the fragmented and variable movement trajectories observed during the cerebellar block. Our findings indicate that cerebellar impairment results in motor deficits due to both inadequate muscle torque and an altered motor control strategy for managing impaired limb dynamics. Additionally, impaired motor control elevates noise, which cannot be entirely mitigated through compensatory strategies.

Benefits of dual-tasking on implicit sensorimotor adaptation

2025-06-24

Benjamin Miller-Mills , Timothy Kwan , Timothy J. Carroll +1 more

ABSTRACT Attention plays a crucial role in maintaining precision and effectiveness in goal-directed actions. Although there is evidence that dividing attention across tasks impairs performance in various domains, the impact … ABSTRACT Attention plays a crucial role in maintaining precision and effectiveness in goal-directed actions. Although there is evidence that dividing attention across tasks impairs performance in various domains, the impact of attention on sensorimotor adaptation remains inconclusive, with some studies reporting deficits and others showing no effects. Because sensorimotor adaptation arises from the interaction of explicit and implicit processes, this discrepancy may reflect differential effects of attention on each process. Here, we investigate how divided attention influences implicit sensorimotor adaptation using an error-clamp paradigm, coupled with a random dot kinematogram (RDK) motion coherence discrimination task. We also assessed whether the timing of the secondary task affects error processing during sensorimotor adaptation by presenting the RDK either during the outward movement (coinciding with error feedback), or the inward movement (following error feedback). We observed that attentional manipulation influenced implicit sensorimotor adaptation only when the RDK was presented on the outward movement, not the inward movement. Remarkably, implicit sensorimotor adaptation was enhanced when attention was divided, compared to when attention was focused entirely on the adaptation task. This suggests that implicit sensorimotor adaptation is sensitive to attentional demand, particularly during the time window where error feedback is received.

Computing muscle mechanical state variables from combined proprioceptive sensory feedback

2025-06-23

Jacob D. Stephens , Lena H. Ting , Timothy C. Cope | Experimental Physiology

Proprioceptive sensory feedback is crucial for the control of movement. In many ways, sensorimotor control loops in the neuromuscular system act as state feedback controllers. These controllers combine input commands … Proprioceptive sensory feedback is crucial for the control of movement. In many ways, sensorimotor control loops in the neuromuscular system act as state feedback controllers. These controllers combine input commands and sensory feedback regarding the mechanical state of the muscle, joint or limb to modulate the mechanical output of the muscles. To understand how these control circuits function, it is necessary to understand fully the mechanical state variables that are signalled by proprioceptive sensory (propriosensory) afferents. Using new computational approaches, we demonstrate how combinations of group Ia and II muscle spindle afferent feedback can allow for tuned responses to force and the rate of force (or length and velocity) and how combinations of muscle spindle and Golgi tendon organ feedback can parse external and internal (self-generated) force. These models suggest that muscle spindle feedback might be used to monitor and control muscle forces in addition to length and velocity and, when combined with tendon organ feedback, can distinguish self-generated from externally imposed forces. Given that these models combine feedback from different sensory afferent types, they emphasize the utility of analysing muscle propriosensors as an integrated population, rather than independently, to gain a better understanding of propriosensory-motor control. Furthermore, these models propose a framework that links neural connectivity in the spinal cord with neuromechanical control. Although considerable work has been done on propriosensory-motor pathways in the CNS, our aim is to build upon this work by emphasizing the mechanical context.

A paradigm to study the learning of muscle activity patterns outside of the natural repertoire

2025-06-23

Ali Ghavampour , Marco Emanuele , Shuja Riyaz Sayyid +4 more | Journal of Neurophysiology

The acquisition of novel muscle activity patterns is a key aspect of motor skill learning which can be seen, for example, when beginner musicians learn new guitar or piano chords. … The acquisition of novel muscle activity patterns is a key aspect of motor skill learning which can be seen, for example, when beginner musicians learn new guitar or piano chords. To study this process, we introduce here a new paradigm that requires learning new patterns of flexion and extension of multiple fingers. First, participants practiced all the 242 possible combinations of isometric finger flexion and extension around the metacarpophalangeal joint (i.e., chords). We found that some chords were initially extremely challenging, but with practice participants could eventually achieve them quickly and synchronously, showing that the initial difficulty did not reflect hard biomechanical constraints imposed by the interaction of tendons and ligaments. In a second experiment we found that chord learning was largely chord-specific and did not generalize to untrained chords. Finally, we explored which factors made it difficult to produce some chords quickly and synchronously. Both variables were well predicted by the muscle activity pattern required by the chord. Specifically, chords that required muscle activity patterns that were smaller and more similar to muscle activity patterns required by everyday hand use, could be produced more synchronously. Together, our results suggest that our new paradigm provides a valuable tool to study the neural processes underlying the acquisition of novel muscle activity patterns in the human motor system.

Effects of repeated trials on the strategy used for a hand laterality judgment task

2025-06-23

Onishi Kohei , Kotaro Takeda , Kenji Kato +2 more | Research Square (Research Square)

<title>Abstract</title> The hand laterality judgment task requires participants to determine whether a picture of a hand picture, presented at various rotational angles, depicts a left or right hand. Task performance … <title>Abstract</title> The hand laterality judgment task requires participants to determine whether a picture of a hand picture, presented at various rotational angles, depicts a left or right hand. Task performance is generally thought to rely on motor imagery (MI) for palm-view pictures and visual imagery (VI) for back-view pictures. However, the influence of repeated task execution on performance strategies remains unclear. This study examined the relationship between self-reported strategies and response time (RT) profiles during a 512-trial hand laterality judgment task in 42 healthy adults. Based on post-task self-reports for palm-view pictures, participants were classified into the MI group, who reported consistently using MI throughout the trials, and the MI–VI group, who reported switching from an MI to VI. In the MI group, RT profiles consistently showed longer RTs for lateral palm-view pictures (outward-pointing fingers) than for medial orientations (inward-pointing fingers), characteristic of MI use, across both halves of the task. The MI–VI group showed similar RT patterns initially, but in the second half, RT differences between lateral and medial orientations diminished, suggesting a shift toward VI-like characteristics. These findings suggest that although both groups may have used MI, RT trends varied according to the participants’ self-reported strategies. In the MI group, both explicit self-report and implicit RT profiles indicated sustained MI use, whereas the MI–VI group, self-reports indicated a strategy shift to VI, and their RT profiles suggest a combined use of MI and VI.

Is it me or the train moving? Humans resolve sensory conflicts with a nonlinear feedback mechanism in balance control

2025-06-23

Lorenz Assländer , Matthias Albrecht , Markus Grüber +1 more | Journal of Neuroscience

Humans use multiple sensory systems to estimate body orientation in space. Sensory contributions change depending on context. A predominant concept for the underlying multisensory integration (MSI) is the linear summation … Humans use multiple sensory systems to estimate body orientation in space. Sensory contributions change depending on context. A predominant concept for the underlying multisensory integration (MSI) is the linear summation of weighted inputs from individual sensory systems. Changes of sensory contributions are typically attributed to some mechanism explicitly adjusting weighting factors. We provide evidence for a conceptually different mechanism that performs a multisensory correction if the reference of a sensory input moves in space without the need to explicitly change sensory weights. The correction is based on a reconstruction of the sensory reference frame motion (RFM) and automatically corrects erroneous inputs, e.g., when looking at a moving train. The proposed RFM estimator contains a nonlinear dead-zone that blocks corrections at slow velocities. We first demonstrate that this mechanism accounts for the apparent changes in sensory contributions. Secondly, using a balance control model, we show predictions of specific distortions in body sway responses to perturbations caused by this nonlinearity. Experiments measuring sway responses of 24 subjects (13 female, 11 male) to visual scene movements confirmed these predictions. The findings indicate that the central nervous system resolves sensory conflicts by an internal reconstruction of the cause of the conflict. Thus, the mechanism links the concept of causal inference to shifts in sensory contributions, providing a cohesive picture of MSI for the estimation of body orientation in space.Significance statement How the central nervous system (CNS) constructs body orientation in space from multiple sensory inputs is a fundamental question in neuroscience. It is a prerequisite to maintain balance, navigate and interact with the world. To estimate body orientation, the CNS dynamically changes the contribution of individual sensory inputs depending on context and reliability of the cues. However, it is not clear how the CNS achieves these dynamic changes. The findings in our study resolve major aspects of this question. Importantly, the proposed solution using nonlinear multisensory feedback contrasts with traditional approaches assuming context-dependent gain-scaling of individual inputs. Thus, our findings demonstrate how complex, intelligent, and unintuitive behavior can emerge from a comparably simple nonlinear feedback mechanism.

Interactively Integrating Reach and Grasp Information in Macaque Premotor Cortex

2025-06-21

Junjun Chen , Guanghao Sun , Yiwei Zhang +4 more | Neuroscience Bulletin

Tilted trials: Assessing performance with varying angle perturbations in visuomotor adaptation task

2025-06-21

Nabaa Ali Sami , Sunaina Soni , Suriya Prakash Muthukrishnan +3 more | Indian Journal of Physiology and Pharmacology

Objectives: This study examined how varying angular perturbations in a visuomotor adaptation task (VMAT) influence implicit and explicit motor learning. The goal was to assess whether implicit adaptation can compensate … Objectives: This study examined how varying angular perturbations in a visuomotor adaptation task (VMAT) influence implicit and explicit motor learning. The goal was to assess whether implicit adaptation can compensate for limitations in explicit learning, particularly in the context of neurological rehabilitation. The study was designed to map the implicit and explicit learning processes in response to a specific perturbation angle in a VMAT using mean directional errors and adaptation as outcome variables. Materials and Methods: Participants performed reaching tasks under visuomotor rotations of different angles (30°, 45° and 60°), presented in block sequences. Performance was measured using mean directional errors and adaptation levels, reaction time (RT) and movement time (MT). The design allowed for the distinction between implicit and explicit learning based on changes in performance across blocks. Results: As expected deterioration in performance was observed (as indicated by mean directional errors) on exposure to altered perturbation during each block. Participants struggled to adapt for smaller angle (the RT and MT failed to improve across block), as they used sensory feedback rather than relying on implicit strategy. Partial adaptation was observed until block 2 for sequences with smaller angles presented together. Small angles (30° and 45°) showed no improvement, indicating that magnitude of movement is critical for precise motor control. Conclusion: This approach is especially important for tasks that require explicit knowledge of subsequent actions. The study highlights the importance of visual representations of hand position in motor learning, and its findings could be applied to specialized rehabilitation training.

Alterations of working memory in adults with sensorimotor disorders.Exploringembodied cognition: a retrospective cohort study

2025-06-20

Julio Ernesto Pérez-Parra , Francia Restrepo de Mejía | Physiotherapy Theory and Practice

This study is based on the embodied cognition dimension of third-generation cognitive models, which postulate that cognition is an embodied, extended, embedded, and enactive phenomenon (4E Theory). To determine whether … This study is based on the embodied cognition dimension of third-generation cognitive models, which postulate that cognition is an embodied, extended, embedded, and enactive phenomenon (4E Theory). To determine whether there are significant differences in working memory between groups of people with sensorimotor disorders due to non-cortical neurological lesions and healthy people matched for sex, age and education. A retrospective cohort study was conducted. Working memory (outcome) was compared between a cohort of individuals with sensorimotor disorders and a control group of healthy individuals matched for sex, age, and education. Each group included 41 individuals between 19 and 55 years of age. The following tests were performed: Working Memory Index of the Wechsler Adult Intelligence Scale IV (WMI-WAIS IV), Trail Making Test - part B (TMT-B), Corsi Block-Tapping Test and Cognitive Event-Related Potentials (ERPs). Statistically significant differences were found in: TMT-B (p = .017), arithmetic component of WMI-WAIS IV (p = .045), N100 (p < .050), N200 (p ≤ .001) and P300 (p ≤ .005) wave latencies, and N200-P300 peak-to-peak amplitude (Pz channel with visual stimulus, p = .050). Better performance was demonstrated in the neuropsychological tests of working memory in the control group: shorter time in TMT-B (intersample difference: 27 seconds) and better score in WMI-WAIS-IV (intersample difference: 1 point). Likewise, the median of their ERP latencies was lower and the N200-P300 amplitude was higher (intersample difference: 0.95 µV). These intersample comparisons could be indicative of the bidirectional influence of motor ability and cognitive performance, particularly related to working memory and psychomotor speed.

Employing a single trial motor equivalent analysis for the assessment of motor learning

2025-06-20

Matthew Beerse , Kimberly Edginton Bigelow , Joaquin A. Barrios | Experimental Brain Research

Abstract The uncontrolled manifold analysis (UCM) is a useful technique for motor learning research enabling the classification of movement variability into solutions and errors. Less explored methodological considerations within the … Abstract The uncontrolled manifold analysis (UCM) is a useful technique for motor learning research enabling the classification of movement variability into solutions and errors. Less explored methodological considerations within the UCM framework are the selection of mean configurations outside of the current performance, as found in the Motor Equivalence Analysis, and a single trial approach. In this study, we demonstrated how calculating deviations away from varying mean configurations within the UCM influences the results and interpretations within motor learning experiments. Twelve young adult subjects (9F/3 M, 20.53 ± 1.25 years old) practiced the kettlebell swing over a one-week time period. We compared deviations from the mean configuration across all repetitions, to the mean of the first ten repetitions before practice and to the mean of their last ten repetitions after practice. Results suggested that subjects abandoned their initial mean performance within the first sets of kettlebell swings and reduced their errors and solutions towards what would become their mean performance after practice. They continued to refine their performance 1 week later. Subjects then completed a transfer task, testing their ability to adapt to a water-filled kettlebell. We evaluated deviations from their mean performance with the metal kettlebell and their mean performance with the water-filled kettlebell. Subjects did not reduce errors towards their mean metal kettlebell performance, but instead towards a new performance that matched the dynamics of the water-filled kettlebell. When performance is expected to change, i.e., motor learning, assessing how the variance structure changes with respect to different mean configurations can provide further insight when using a UCM approach.

Targeting Upper-Limb Sensory Gaps

2025-06-19

Sahar Zaidi , Sohrab Ahmad Khan , Charu Chhabra +2 more | CRC Press eBooks

The effects of the implementation order of implicit and explicit learning methods on learners' task enjoyment and motor skill acquisition

2025-06-19

Yuki Matsuura , Hiroki Matsuoka , Yoshifumi Isa +1 more | Frontiers in Sports and Active Living

Purpose This study aimed to explore the effect of the order of two learning methods (one based on implicit and another on explicit learning) on students' enjoyment and ability to … Purpose This study aimed to explore the effect of the order of two learning methods (one based on implicit and another on explicit learning) on students' enjoyment and ability to acquire motor skills in gymnastics. Apparatus gymnastics courses for pre-service teachers were analyzed using information and communication technology. Methods The participants were 21 pre-service teachers in Japan. They were divided into two groups with equal skill levels, with the order of learning method alternating between the groups. Seven lessons were conducted in total. Changes in enjoyment of learning mat exercises, physical sensation during practice, and self-evaluation of skill progress were examined before and after class. Results In implicit learning, the learners enjoyed activities without concern about the presence of others; however, their self-evaluation of skill progress was lower than that in explicit learning. In explicit learning, learners enjoyed activities less than in implicit learning; however, their self-evaluation of skill progress was higher than that in implicit learning, and they tried to perform tasks with higher-level skills. This was possibly because learners experienced enjoyment without concern about the presence of others implicit learning, followed by the opportunity to improve their self-evaluation and attempt higher-level tasks in explicit learning. Conclusion The findings suggest optimal instructional strategies should implement implicit learning to foster enjoyment and sensory-motor exploration, followed by explicit learning to enhance progress self-evaluation and promote performance of advanced skill challenges.

Divisive attenuation based on noisy sensorimotor predictions accounts for excess variability in self-touch

2025-06-18

Nicola Valè , Ivan Tomić , Zahara Gironés +3 more | Journal of Neurophysiology

When one part of the body exerts force on another, the resulting tactile sensation is perceived as weaker than when the same force is applied by an external agent. This … When one part of the body exerts force on another, the resulting tactile sensation is perceived as weaker than when the same force is applied by an external agent. This phenomenon has been studied using a force matching task, in which observers are first exposed to an external force on a passive finger and then instructed to reproduce the sensation by directly pressing on the passive finger with a finger of the other hand: healthy participants consistently exceed the original force level. However, this exaggeration of the target force is not observed if the observer generates the matching force indirectly, by adjusting a joystick or slider that controls the force output of a motor. Here we present the first detailed computational account of the processes leading to exaggeration of target forces in the force matching task, incorporating attenuation of sensory signals based on motor predictions. The model elucidates previously unappreciated contributions of multiple sources of noise, including memory noise, in determining matching force output, and shows that quantifying attenuation as the discrepancy between direct and indirect self-generated forces isolates its predictive component. Our computational account makes the prediction that attenuated sensations will display greater trial-to-trial variability than unattenuated ones, because they incorporate additional noise from motor prediction. Quantitative model fitting of new and existing force matching data confirmed the prediction of excess variability in self-generated forces and provided evidence for a divisive rather than subtractive mechanism of attenuation, while highlighting its predictive nature.

Direction-dependent effects of gravity on speed-accuracy trade-off during vertical pointing movements

2025-06-16

Soma Okuuchi , Shinji Yamamoto , Keisuke Tani +1 more | Experimental Brain Research

Effects of aging on upper body express visuomotor responses while reaching under varying postural demands

2025-06-15

Lucas S. Billen , Madeline Gilchrist , Vivian Weerdesteyn +1 more | bioRxiv (Cold Spring Harbor Laboratory)

Humans can react remarkably quickly to novel or displaced visual stimuli when time is of the essence. Such movements are thought to be initiated by a subcortical fast visuomotor network, … Humans can react remarkably quickly to novel or displaced visual stimuli when time is of the essence. Such movements are thought to be initiated by a subcortical fast visuomotor network, but it is unclear how this network declines with age. Past work in the upper limb has detailed delayed reaching corrections to jumped visual stimuli in the elderly, but the underlying mechanisms contributing to these changes of the fast visuomotor network are poorly understood. Conversely, work in the lower limb has reported delayed muscle recruitment during obstacle avoidance, but such findings may be confounded by age-related challenges in postural control. The output of the fast visuomotor network can be quantified by measuring express visuomotor responses (EVRs), which are the earliest and very short-latency bursts of muscle activity that follow visual target presentation. Here, we compare the prevalence, latency, and magnitude of EVRs in elderly (58-80 years old) and younger (18-25 years old) participants performing visually-guided reaches. We also investigated the impact of postural stability by having participants reach either while seated on a stable chair, or on a wobble stool. Both the elderly and younger cohorts expressed EVRs, but EVRs in the elderly were comparatively less frequent, and had longer latencies and smaller magnitude. Postural instability had no effects on these outcomes. Our results suggest age-related declines in the fast visuomotor network, potentially resulting from deterioration of underlying circuits and a prioritization of stability over speed. This study serves as an important standard for future research investigating clinical populations.

Integration of Motor Planning and Execution through Latent Structure Reorganization in the Posterior Parietal Cortex

2025-06-15

Stefano Diomedi , F Vaccari , Kostas Hadjidimitrakis +2 more | bioRxiv (Cold Spring Harbor Laboratory)

The posterior parietal cortex (PPC) plays a central role in sensorimotor control, performing visuomotor transformations, supporting planning, and providing visual feedback. However, it is unknown how the neural populations in … The posterior parietal cortex (PPC) plays a central role in sensorimotor control, performing visuomotor transformations, supporting planning, and providing visual feedback. However, it is unknown how the neural populations in different PPC areas organize their activity during this process. It has been proposed that PPC activity reflects population-level dynamics rather than distinct subpopulations, raising the question of how the population flexibly reorganize between the two main phases of motor control, planning and execution. To address this question, we analyzed neural dynamics in three PPC areas (PE, PEc, V6A) in the context of a delayed reaching task, applying dimensionality reduction techniques. This approach allows identifying whether activity in each area is organized into independent or partially overlapping dynamics across task phases. We found evidence of area-specific population subspaces, distinct for movement planning and execution. Specifically, the analysis revealed that in PE, which is a predominantly somatomotor area, neural activity occupied nearly orthogonal subspaces between the two phases, suggesting independent dynamics for movement planning and execution. In contrast, in V6A and PEc, which are involved in visuomotor transformations, we identified both shared and exclusive subspaces, indicating a more flexible representation of motor information in these areas. Overall, our findings suggest that parietal circuits combine both separation and sharing of neural representation to support computations during the different movement stages, providing new insights into the role of the PPC in generating flexible motor behavior.

Decoupling simultaneous motor imagination and execution via orthogonal ECoG neural representations

2025-06-14

Leonardo Pollina , Lucas Struber , Valeria de Seta +7 more | bioRxiv (Cold Spring Harbor Laboratory)

The brain coordinates multiple parallel motor programs, ensuring synergy and preventing interference during movements. Yet, performance often degrades when brain-machine interfaces are used during concurrent tasks or ongoing movements. We … The brain coordinates multiple parallel motor programs, ensuring synergy and preventing interference during movements. Yet, performance often degrades when brain-machine interfaces are used during concurrent tasks or ongoing movements. We suggest that latent neural representations may represent a strategy to solve this issue. In this study, we addressed this question using neural signals from a tetraplegic individual with partial residual motor function, implanted with a wireless epidural electrocorticography (ECoG) device. By adapting dimensionality reduction techniques, we found that motor execution and motor imagery span partially overlapping subspaces in mesoscale neural signals, shaped by specific frequency band contributions. Despite substantial shared variance, we show that identifying orthogonal, condition-specific dimensions enables successful decoding of executed and imagined movements, even when performed simultaneously. These findings show that ECoG signals can expose separable neural subspaces, allowing executed and imagined actions to be harnessed independently and in concert. This opens a promising avenue to develop brain-machine interfaces that can simultaneously control multiple external devices or operate alongside natural movements.

The Interplay Between Haptic Guidance and Personality Traits in Robotic-assisted Motor Learning

2025-06-12

Alberto Garzás-Villar , Caspar Boersma , Alexis Derumigny +4 more | Research Square (Research Square)

<title>Abstract</title> <bold>Background:</bold> Robotic devices have shown promise in supporting motor (re)learning. However, there is a limited understanding of how personality traits influence the effectiveness of robot-aided training strategies. <bold>Methods:</bold> We … <title>Abstract</title> <bold>Background:</bold> Robotic devices have shown promise in supporting motor (re)learning. However, there is a limited understanding of how personality traits influence the effectiveness of robot-aided training strategies. <bold>Methods:</bold> We conducted a motor learning experiment with 40 unimpaired participants who trained to control a virtual pendulum using a robotic haptic device. Participants were divided into two groups, one receiving haptic guidance during training and a second one without assistance. Short- and long-term retention was assessed, and relationships between personality traits, performance metrics, and human-robot interaction metrics were analyzed. <bold>Results:</bold> Participants with high Transform of Challenge or external Locus of Control (LOC) characteristics who received physical guidance during training reduced the human-robot interaction forces to a lesser extent compared to the ones who did not receive guidance. Additionally, participants with a high Free Spirit gaming style showed greater sensitivity to how their perception of the guidance affected their performance during the retention phases. <bold>Conclusion:</bold> Our findings suggest that autotelic personality, Locus of Control, and gaming style modulate motor learning outcomes during robotic-assisted training, affecting both performance and human-robot interaction metrics.This highlights the potential of integrating personality-based adaptations in robot-aided rehabilitation protocols to enhance performance and motor (re)learning.Future works should explore the relationship between personality traits and psychological states (e.g., perceived difficulty, attention) across diverse tasks and guidance methods in clinical populations.

Interference underlies attenuation upon relearning in sensorimotor adaptation

2025-06-05

Guy Avraham , Richard B. Ivry | eNeuro

Savings refers to the gain in performance upon relearning. In sensorimotor adaptation, savings is tested by having participants adapt to perturbed feedback and, following a washout block during which the … Savings refers to the gain in performance upon relearning. In sensorimotor adaptation, savings is tested by having participants adapt to perturbed feedback and, following a washout block during which the system resets to baseline, presenting the same perturbation again. While savings has been observed with these tasks, we have shown that the contribution from implicit adaptation, a process that uses errors to recalibrate the sensorimotor map, is attenuated upon relearning (Avraham et al., 2021). Here, we test the hypothesis that this attenuation is due to interference arising from the different relationship between the movement and the feedback during washout. Removing the perturbation at the start of the washout block typically results in a salient error signal in the opposite direction to that observed during learning. We first replicated the finding that implicit adaptation is attenuated following a washout period that introduces salient opposite errors. When we eliminated feedback during washout, relearning was no longer attenuated, consistent with the interference hypothesis. Next, we created a scenario in which the perceived errors during washout were not salient, falling within the range of motor noise. Nonetheless, attenuation was still prominent. Inspired by this observation, we tested participants with an extended initial experience with veridical feedback and found that this was sufficient to attenuate adaptation during the first learning block. This effect was context-specific and did not generalize to other movements. Taken together, the implicit sensorimotor adaptation system is highly sensitive to memory interference from a recent experience with a discrepant action-outcome contingency. Significant statement Relearning refers to the situation in which a previously learned, but forgotten task, is re-introduced. Typically, performance is facilitated upon relearning. One exception is implicit adaptation, an error-based process in which the sensorimotor system compensates for external perturbations: For implicit adaptation, relearning is attenuated, a phenomenon at odds with models of motor learning that assume that error sensitivity increases with practice. Here, we demonstrate that attenuation upon relearning is the result of interference between competing memories. We show that the adaptation system is sensitive to interference when multiple memories are associated with similar movements. Indeed, interference is not limited to a memory of competing errors but is also observed during initial learning after prolonged experience with non-perturbed movements.