scholarly journals Formation of model-free motor memories during motor adaptation depends on perturbation schedule

2015 ◽  
Vol 113 (7) ◽  
pp. 2733-2741 ◽  
Author(s):  
Jean-Jacques Orban de Xivry ◽  
Philippe Lefèvre
Keyword(s):  
Motor Adaptation ◽  
External Perturbation ◽  
Motor Memory ◽  
Visuomotor Rotation ◽  
Experimental Conditions ◽  
Model Free ◽  
Neural Representations ◽  
Adaptation State ◽  
Gradual Introduction ◽  
Dependent Learning

Motor adaptation to an external perturbation relies on several mechanisms such as model-based, model-free, strategic, or repetition-dependent learning. Depending on the experimental conditions, each of these mechanisms has more or less weight in the final adaptation state. Here we focused on the conditions that lead to the formation of a model-free motor memory (Huang VS, Haith AM, Mazzoni P, Krakauer JW. Neuron 70: 787–801, 2011), i.e., a memory that does not depend on an internal model or on the size or direction of the errors experienced during the learning. The formation of such model-free motor memory was hypothesized to depend on the schedule of the perturbation (Orban de Xivry JJ, Ahmadi-Pajouh MA, Harran MD, Salimpour Y, Shadmehr R. J Neurophysiol 109: 124–136, 2013). Here we built on this observation by directly testing the nature of the motor memory after abrupt or gradual introduction of a visuomotor rotation, in an experimental paradigm where the presence of model-free motor memory can be identified (Huang VS, Haith AM, Mazzoni P, Krakauer JW. Neuron 70: 787–801, 2011). We found that relearning was faster after abrupt than gradual perturbation, which suggests that model-free learning is reduced during gradual adaptation to a visuomotor rotation. In addition, the presence of savings after abrupt introduction of the perturbation but gradual extinction of the motor memory suggests that unexpected errors are necessary to induce a model-free motor memory. Overall, these data support the hypothesis that different perturbation schedules do not lead to a more or less stabilized motor memory but to distinct motor memories with different attributes and neural representations.

scholarly journals Formation of a long-term memory for visuomotor adaptation following only a few trials of practice

2015 ◽  
Vol 114 (2) ◽  
pp. 969-977 ◽  
Author(s):  
David M. Huberdeau ◽  
Adrian M. Haith ◽  
John W. Krakauer
Keyword(s):  
Human Subjects ◽  
Motor Adaptation ◽  
Visuomotor Adaptation ◽  
Reaching Movements ◽  
Motor Memory ◽  
Long Term Memory ◽  
Visuomotor Rotation ◽  
Initial Exposure ◽  
Term Memory

The term savings refers to faster motor adaptation upon reexposure to a previously experienced perturbation, a phenomenon thought to reflect the existence of a long-term motor memory. It is commonly assumed that sustained practice during the first perturbation exposure is necessary to create this memory. Here we sought to test this assumption by determining the minimum amount of experience necessary during initial adaptation to a visuomotor rotation to bring about savings the following day. Four groups of human subjects experienced 2, 5, 10, or 40 trials of a counterclockwise 30° cursor rotation during reaching movements on one day and were retested the following day to assay for savings. Groups that experienced five trials or more of adaptation on day 1 showed clear savings on day 2. Subjects in all groups learned significantly more from the first rotation trial on day 2 than on day 1, but this learning rate advantage was maintained only in groups that had reached asymptote during the initial exposure. Additional experiments revealed that savings occurred when the magnitude, but not the direction, of the rotation differed across exposures, and when a 5-min break, rather than an overnight one, separated the first and second exposure. The overall pattern of savings we observe across conditions can be explained as rapid retrieval of the state of learning attained during the first exposure rather than as modulation of sensitivity to error. We conclude that a long-term memory for compensating for a perturbation can be rapidly acquired and rapidly retrieved.

Sensorimotor knowledge from task-irrelevant feedback contributes to motor learning

2021 ◽  
Author(s):  
Wanying Jiang ◽  
Yajie Liu ◽  
Yuqing Bi ◽  
Kunlin Wei
Keyword(s):  
Motor Learning ◽  
Perceptual Learning ◽  
Implicit Learning ◽  
Motor Adaptation ◽  
Strategic Learning ◽  
Visuomotor Rotation ◽  
Saving Effect ◽  
Sensorimotor Knowledge ◽  
Sensory Processes ◽  
Task Irrelevant

Exposure to task-irrelevant feedback leads to perceptual learning, but its effect on motor learning has been understudied. Here we asked human participants to reach a visual target with a hand-controlled cursor while observing another cursor moving independently in a different direction. While the task-irrelevant feedback did not change the main task's performance, it elicited robust savings in subsequent adaptation to classical visuomotor rotation perturbation. We demonstrated that the saving effect resulted from a faster formation of strategic learning through a series of experiments, not from gains in the implicit learning process. Furthermore, the saving effect was robust against drastic changes in stimulus features (i.e., rotation size or direction) or task types (i.e., for motor adaptation and skill learning). However, the effect was absent when the task-irrelevant feedback did not carry the visuomotor relationship embedded in visuomotor rotation. Thus, though previous research on perceptual learning has related task-irrelevant feedback to changes in early sensory processes, our findings support its role in acquiring abstract sensorimotor knowledge during motor learning. Motor learning studies have traditionally focused on task-relevant feedback, but our study extends the scope of feedback processes and sheds new light on the dichotomy of explicit and implicit learning in motor adaptation as well as motor structure learning.

scholarly journals Neural signatures of reward and sensory error feedback processing in motor learning

2019 ◽  
Vol 121 (4) ◽  
pp. 1561-1574 ◽  
Author(s):  
Dimitrios J. Palidis ◽  
Joshua G. A. Cashaback ◽  
Paul L. Gribble
Keyword(s):  
Visual Feedback ◽  
Motor Adaptation ◽  
Learning Task ◽  
Reward Learning ◽  
P300 Amplitude ◽  
Error Feedback ◽  
Learning Mechanisms ◽  
Visuomotor Rotation ◽  
Feedback Processing ◽  
Motor Commands

At least two distinct processes have been identified by which motor commands are adapted according to movement-related feedback: reward-based learning and sensory error-based learning. In sensory error-based learning, mappings between sensory targets and motor commands are recalibrated according to sensory error feedback. In reward-based learning, motor commands are associated with subjective value, such that successful actions are reinforced. We designed two tasks to isolate reward- and sensory error-based motor adaptation, and we used electroencephalography in humans to identify and dissociate the neural correlates of reward and sensory error feedback processing. We designed a visuomotor rotation task to isolate sensory error-based learning that was induced by altered visual feedback of hand position. In a reward learning task, we isolated reward-based learning induced by binary reward feedback that was decoupled from the visual target. A fronto-central event-related potential called the feedback-related negativity (FRN) was elicited specifically by binary reward feedback but not sensory error feedback. A more posterior component called the P300 was evoked by feedback in both tasks. In the visuomotor rotation task, P300 amplitude was increased by sensory error induced by perturbed visual feedback and was correlated with learning rate. In the reward learning task, P300 amplitude was increased by reward relative to nonreward and by surprise regardless of feedback valence. We propose that during motor adaptation the FRN specifically reflects a reward-based learning signal whereas the P300 reflects feedback processing that is related to adaptation more generally. NEW & NOTEWORTHY We studied the event-related potentials evoked by feedback stimuli during motor adaptation tasks that isolate reward- and sensory error-based learning mechanisms. We found that the feedback-related negativity was specifically elicited by binary reward feedback, whereas the P300 was observed in both tasks. These results reveal neural processes associated with different learning mechanisms and elucidate which classes of errors, from a computational standpoint, elicit the feedback-related negativity and P300.

scholarly journals Relative sensitivity of explicit reaiming and implicit motor adaptation

2018 ◽  
Vol 120 (5) ◽  
pp. 2640-2648 ◽  
Author(s):  
Sarah A. Hutter ◽  
Jordan A. Taylor
Keyword(s):  
Motor Adaptation ◽  
Relative Sensitivity ◽  
Sensitivity Function ◽  
Prior Work ◽  
Visuomotor Rotation ◽  
Small Perturbations ◽  
Task Relevance ◽  
Error Magnitude ◽  
Implicit Motor ◽  
Visual Error

It has become increasingly clear that learning in visuomotor rotation tasks, which induce an angular mismatch between movements of the hand and visual feedback, largely results from the combined effort of two distinct processes: implicit motor adaptation and explicit reaiming. However, it remains unclear how these two processes work together to produce trial-by-trial learning. Previous work has found that implicit motor adaptation operates automatically, regardless of task relevance, and saturates for large errors. In contrast, little is known about the automaticity of explicit reaiming and its sensitivity to error magnitude. Here we sought to characterize the automaticity and sensitivity function of these two processes to determine how they work together to facilitate performance in a visuomotor rotation task. We found that implicit adaptation scales relative to the visual error but only for small perturbations—replicating prior work. In contrast, explicit reaiming scales linearly for all tested perturbation sizes. Furthermore, the consistency of the perturbation appears to diminish both implicit adaptation and explicit reaiming, but to different degrees. Whereas implicit adaptation always displayed a response to the error, explicit reaiming was only engaged when errors displayed a minimal degree of consistency. This comports with the idea that implicit adaptation is obligatory and less flexible, whereas explicit reaiming is volitional and flexible. NEW & NOTEWORTHY This paper provides the first psychometric sensitivity function for explicit reaiming. Additionally, we show that the sensitivities of both implicit adaptation and explicit reaiming are influenced by consistency of errors. The pattern of results across two experiments further supports the idea that implicit adaptation is largely inflexible, whereas explicit reaiming is flexible and can be suppressed when unnecessary.

scholarly journals Ultra-fast accurate reconstruction of spiking activity from calcium imaging data

2018 ◽  
Vol 119 (5) ◽  
pp. 1863-1878 ◽  
Author(s):  
Vahid Rahmati ◽  
Knut Kirmse ◽  
Knut Holthoff ◽  
Stefan J. Kiebel
Keyword(s):  
Calcium Imaging ◽  
Reconstruction Method ◽  
Imaging Data ◽  
Decay Kinetics ◽  
Experimental Conditions ◽  
Model Free ◽  
Reconstruction Methods ◽  
Wide Range ◽  
Fast Processing ◽  
Spiking Activity

Calcium imaging provides an indirect observation of the underlying neural dynamics and enables the functional analysis of neuronal populations. However, the recorded fluorescence traces are temporally smeared, thus making the reconstruction of exact spiking activity challenging. Most of the established methods to tackle this issue are limited in dealing with issues such as the variability in the kinetics of fluorescence transients, fast processing of long-term data, high firing rates, and measurement noise. We propose a novel, heuristic reconstruction method to overcome these limitations. By using both synthetic and experimental data, we demonstrate the four main features of this method: 1) it accurately reconstructs both isolated spikes and within-burst spikes, and the spike count per fluorescence transient, from a given noisy fluorescence trace; 2) it performs the reconstruction of a trace extracted from 1,000,000 frames in less than 2 s; 3) it adapts to transients with different rise and decay kinetics or amplitudes, both within and across single neurons; and 4) it has only one key parameter, which we will show can be set in a nearly automatic way to an approximately optimal value. Furthermore, we demonstrate the ability of the method to effectively correct for fast and rather complex, slowly varying drifts as frequently observed in in vivo data. NEW & NOTEWORTHY Reconstruction of spiking activities from calcium imaging data remains challenging. Most of the established reconstruction methods not only have limitations in adapting to systematic variations in the data and fast processing of large amounts of data, but their results also depend on the user’s experience. To overcome these limitations, we present a novel, heuristic model-free-type method that enables an ultra-fast, accurate, near-automatic reconstruction from data recorded under a wide range of experimental conditions.

scholarly journals Relative sensitivity of explicit re-aiming and implicit motor adaptation

2018 ◽  
Author(s):  
Sarah A. Hutter ◽  
Jordan A. Taylor
Keyword(s):  
Motor Adaptation ◽  
Relative Sensitivity ◽  
Sensitivity Function ◽  
Prior Work ◽  
Visuomotor Rotation ◽  
Small Perturbations ◽  
Error Magnitude ◽  
Implicit Motor ◽  
Task Relevancy ◽  
Visual Error

AbstractIt has become increasingly clear that learning in visuomotor rotation tasks, which induce an angular mismatch between movements of the hand and visual feedback, largely results from the combined effort of two distinct processes: implicit motor adaptation and explicit re-aiming. However, it remains unclear how these two processes work together to produce trial-by-trial learning. Previous work has found that implicit motor adaptation operates automatically, regardless of task relevancy, and saturates for large errors. In contrast, little is known about the automaticity of explicit re-aiming and its sensitivity to error magnitude. Here we sought to characterize the automaticity and sensitivity function of these two processes to determine how they work together to facilitate performance in a visuomotor rotation task. We found that implicit adaptation scales relative to the visual error, but only for small perturbations – replicating prior work. In contrast, explicit re-aiming scales linearly for all tested perturbation sizes. Furthermore, the consistency of the perturbation appears to diminish both implicit adaptation and explicit re-aiming, but to different degrees. Whereas implicit adaptation always displayed a response to the error, explicit re-aiming was only engaged when errors displayed a minimal degree of consistency. This comports with the idea that implicit adaptation is obligatory and less flexible, while explicit re-aiming is volitional and flexible.

scholarly journals Robotic Assessment of Wrist Proprioception During Kinaesthetic Perturbations: A Neuroergonomic Approach

2021 ◽  
Vol 15 ◽  
Author(s):  
Erika D'Antonio ◽  
Elisa Galofaro ◽  
Jacopo Zenzeri ◽  
Fabrizio Patané ◽  
Jürgen Konczak ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Neurological Diseases ◽  
External Perturbation ◽  
Recovery Process ◽  
Position Sense ◽  
Matching Task ◽  
Experimental Conditions ◽  
Clinical Scales ◽  
Flexion Extension ◽  
Presentation Sequence

Position sense refers to an aspect of proprioception crucial for motor control and learning. The onset of neurological diseases can damage such sensory afference, with consequent motor disorders dramatically reducing the associated recovery process. In regular clinical practice, assessment of proprioceptive deficits is run by means of clinical scales which do not provide quantitative measurements. However, existing robotic solutions usually do not involve multi-joint movements but are mostly applied to a single proximal or distal joint. The present work provides a testing paradigm for assessing proprioception during coordinated multi-joint distal movements and in presence of kinaesthetic perturbations: we evaluated healthy subjects' ability to match proprioceptive targets along two of the three wrist's degrees of freedom, flexion/extension and abduction/adduction. By introducing rotations along the pronation/supination axis not involved in the matching task, we tested two experimental conditions, which differed in terms of the temporal imposition of the external perturbation: in the first one, the disturbance was provided after the presentation of the proprioceptive target, while in the second one, the rotation of the pronation/ supination axis was imposed during the proprioceptive target presentation. We investigated if (i) the amplitude of the perturbation along the pronation/supination would lead to proprioceptive miscalibration; (ii) the encoding of proprioceptive target, would be influenced by the presentation sequence between the target itself and the rotational disturbance. Eighteen participants were tested by means of a haptic neuroergonomic wrist device: our findings provided evidence that the order of disturbance presentation does not alter proprioceptive acuity. Yet, a further effect has been noticed: proprioception is highly anisotropic and dependent on perturbation amplitude. Unexpectedly, the configuration of the forearm highly influences sensory feedbacks, and significantly alters subjects' performance in matching the proprioceptive targets, defining portions of the wrist workspace where kinaesthetic and proprioceptive acuity are more sensitive. This finding may suggest solutions and applications in multiple fields: from general haptics where, knowing how wrist configuration influences proprioception, might suggest new neuroergonomic solutions in device design, to clinical evaluation after neurological damage, where accurately assessing proprioceptive deficits can dramatically complement regular therapy for a better prediction of the recovery path.

scholarly journals Opinion: Neural differentiation of incorrectly predicted memories

2018 ◽  
Author(s):  
Andrea Greve ◽  
Hunar Abdulrahman ◽  
Richard Henson
Keyword(s):  
Prediction Error ◽  
Neural Differentiation ◽  
Recent Article ◽  
Transitive Inference ◽  
Experimental Conditions ◽  
Neural Representations ◽  
New Information

In their recent article ‘Neural differentiation of incorrectly predicted memories’, Kim et al. (2017) investigate how neural representations of items change when they are incorrectly predicted and subsequently restudied. The authors conclude such items undergo representational differentiation, i.e. a decreased overlap in the representations of an item and its context. We suggest the results are equally compatible with the reverse mechanism of integration, i.e. increased learning of new information and present simulations to demonstrate this. More importantly, we show how new experimental conditions could distinguish integration from differentiation and discuss how the results fit with recent suggestions about prediction-error driven learning and transitive inference.

scholarly journals Kinetics of Solid-Gas Reactions and Their Application to Carbonate Looping Systems

Energies ◽  
2019 ◽  
Vol 12 (15) ◽  
pp. 2981 ◽  
Author(s):  
Larissa Fedunik-Hofman ◽  
Alicia Bayon ◽  
Scott W. Donne
Keyword(s):  
Kinetic Analysis ◽  
Kinetic Parameters ◽  
Carbon Capture ◽  
Large Scale ◽  
Chemical Engineering ◽  
Kinetic Method ◽  
Experimental Conditions ◽  
Exponential Factor ◽  
Model Free ◽  
Gas Reactions

Reaction kinetics is an important field of study in chemical engineering to translate laboratory-scale studies to large-scale reactor conditions. The procedures used to determine kinetic parameters (activation energy, pre-exponential factor and the reaction model) include model-fitting, model-free and generalized methods, which have been extensively used in published literature to model solid-gas reactions. A comprehensive review of kinetic analysis methods will be presented using the example of carbonate looping, an important process applied to thermochemical energy storage and carbon capture technologies. The kinetic parameters obtained by different methods for both the calcination and carbonation reactions are compared. The experimental conditions, material properties and the kinetic method are found to strongly influence the kinetic parameters and recommendations are provided for the analysis of both reactions. Of the methods, isoconversional techniques are encouraged to arrive at non-mechanistic parameters for calcination, while for carbonation, material characterization is recommended before choosing a specific kinetic analysis method.

scholarly journals The temporal stability of visuomotor adaptation generalization

2017 ◽  
Vol 118 (4) ◽  
pp. 2435-2447 ◽  
Author(s):  
Weiwei Zhou ◽  
Justin Fitzgerald ◽  
Katrina Colucci-Chang ◽  
Karthik G. Murthy ◽  
Wilsaan M. Joiner
Keyword(s):  
Visual Feedback ◽  
Temporal Stability ◽  
Motor Adaptation ◽  
Visuomotor Adaptation ◽  
Time Dependent ◽  
Active Movement ◽  
Temporal Decay ◽  
Temporal Properties ◽  
Three Delays ◽  
Dependent Learning

Movement adaptation in response to systematic motor perturbations exhibits distinct spatial and temporal properties. These characteristics are typically studied in isolation, leaving the interaction largely unknown. Here we examined how the temporal decay of visuomotor adaptation influences the spatial generalization of the motor recalibration. First, we quantified the extent to which adaptation decayed over time. Subjects reached to a peripheral target, and a rotation was applied to the visual feedback of the unseen motion. The retention of this adaptation over different delays (0–120 s) 1) decreased by 29.0 ± 6.8% at the longest delay and 2) was represented by a simple exponential, with a time constant of 22.5 ± 5.6 s. On the basis of this relationship we simulated how the spatial generalization of adaptation would change with delay. To test this directly, we trained additional subjects with the same perturbation and assessed transfer to 19 different locations (spaced 15° apart, symmetric around the trained location) and examined three delays (~4, 12, and 25 s). Consistent with the simulation, we found that generalization around the trained direction (±15°) significantly decreased with delay and distance, while locations >60° displayed near-constant spatiotemporal transfer. Intermediate distances (30° and 45°) showed a difference in transfer across space, but this amount was approximately constant across time. Interestingly, the decay at the trained direction was faster than that based purely on time, suggesting that the spatial transfer of adaptation is modified by concurrent passive (time dependent) and active (movement dependent) processes. NEW & NOTEWORTHY Short-term motor adaptation exhibits distinct spatial and temporal characteristics. Here we investigated the interaction of these features, utilizing a simple motor adaptation paradigm (recalibration of reaching arm movements in response to rotated visual feedback). We examined the changes in the spatial generalization of motor adaptation for different temporal manipulations and report that the spatiotemporal generalization of motor adaptation is generally local and is influenced by both passive (time dependent) and active (movement dependent) learning processes.

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