scholarly journals The Effect of Visual Uncertainty on Implicit Motor Adaptation

2020 ◽  
Author(s):  
Jonathan S. Tsay ◽  
Guy Avraham ◽  
Hyosub E. Kim ◽  
Darius E. Parvin ◽  
Zixuan Wang ◽  
...  
Keyword(s):  
Alternative Hypothesis ◽  
Visuomotor Adaptation ◽  
Modular System ◽  
Feedback Signal ◽  
Sensorimotor Adaptation ◽  
Prediction Errors ◽  
Error Signal ◽  
The Difference ◽  
Visual Error ◽  
Sensorimotor Map

ABSTRACTSensorimotor adaptation is driven by sensory prediction errors, the difference between the predicted and actual feedback. When the position of the feedback is made uncertain, adaptation is attenuated. This effect, in the context of optimal sensory integration models, has been attributed to a weakening of the error signal driving adaptation. Here we consider an alternative hypothesis, namely that uncertainty alters the perceived location of the feedback. We present two visuomotor adaptation experiments to compare these hypotheses, varying the size and uncertainty of a visual error signal. Uncertainty attenuated learning when the error size was small but had no effect when the error size was large. This pattern of results favors the hypothesis that uncertainty does not impact the strength of the error signal, but rather, leads to mis-localization of the error. We formalize these ideas to offer a novel perspective on the effect of visual uncertainty on implicit sensorimotor adaptation.SIGNIFICANCE STATEMENTCurrent models of sensorimotor adaptation assume that the rate of learning will be related to properties of the error signal (e.g., size, consistency, relevance). Recent evidence has challenged this view, pointing to a rigid, modular system, one that automatically recalibrates the sensorimotor map in response to movement errors, with minimal constraint. In light of these developments, this study revisits the influence of feedback uncertainty on sensorimotor adaptation. Adaptation was attenuated in response to a noisy feedback signal, but the effect was only manifest for small errors and not for large errors. This interaction suggests that uncertainty does not weaken the error signal. Rather, it may influence the perceived location of the feedback and thus the change in the sensorimotor map induced by that error. These ideas are formalized to show how the motor system remains exquisitely calibrated, even if adaptation is largely insensitive to the statistics of error signals.

scholarly journals Individuals with cerebellar degeneration show similar adaptation deficits with large and small visuomotor errors

2013 ◽  
Vol 109 (4) ◽  
pp. 1164-1173 ◽  
Author(s):  
John E. Schlerf ◽  
Jing Xu ◽  
Nola M. Klemfuss ◽  
Thomas L. Griffiths ◽  
Richard B. Ivry
Keyword(s):  
Sensory Information ◽  
External Perturbation ◽  
Visuomotor Adaptation ◽  
Error Signal ◽  
Credit Assignment ◽  
Visuomotor Rotation ◽  
Motor Variability ◽  
Large Step ◽  
The Difference ◽  
Computational Analyses

The cerebellum has long been recognized to play an important role in motor adaptation. Individuals with cerebellar ataxia exhibit impaired learning in visuomotor adaptation tasks such as prism adaptation and force field learning. Both types of tasks involve the adjustment of an internal model to compensate for an external perturbation. This updating process is error driven, with the error signal based on the difference between anticipated and actual sensory information. This process may entail a credit assignment problem, with a distinction made between error arising from faulty representation of the environment and error arising from noise in the controller. We hypothesized that people with ataxia may perform poorly at visuomotor adaptation because they attribute a greater proportion of their error to their motor control difficulties. We tested this hypothesis using a computational model based on a Kalman filter. We imposed a 20-deg visuomotor rotation in either a single large step or in a series of smaller 5-deg steps. The ataxic group exhibited a comparable deficit in both conditions. The computational analyses indicate that the patients' deficit cannot be accounted for simply by their increased motor variability. Rather, the patients' deficit in learning may be related to difficulty in estimating the instability in the environment or variability in their motor system.

scholarly journals A Synthesis of the Many Errors and Learning Processes of Visuomotor Adaptation

2021 ◽  
Author(s):  
J. Ryan Morehead ◽  
Jean-Jacques Orban de Xivry
Keyword(s):  
Task Performance ◽  
Visuomotor Adaptation ◽  
Learning Processes ◽  
Skill Learning ◽  
Sensorimotor Adaptation ◽  
Prediction Errors ◽  
Control Measurement ◽  
Performance Error ◽  
Nuanced Understanding ◽  
Sensory Prediction

Visuomotor adaptation has one of the oldest experimental histories in psychology and neuroscience, yet its precise nature has always been a topic of debate. Here we offer a survey and synthesis of recent work on visuomotor adaptation that we hope will prove illuminating for this ongoing dialogue. We discuss three types of error signals that drive learning in adaptation tasks: task performance error, sensory prediction-error, and a binary target hitting error. Each of these errors has been shown to drive distinct learning processes. Namely, both target hitting errors and putative sensory prediction-errors drive an implicit change in visuomotor maps, while task performance error drives learning of explicit strategy use and non-motor decision-making. Each of these learning processes contributes to the overall learning that takes place in visuomotor adaptation tasks, and although the learning processes and error signals are independent, they interact in a complex manner. We outline many task contexts where the operation of these processes is counter-intuitive and offer general guidelines for their control, measurement and interpretation. We believe this new framework unifies several disparate threads of research in sensorimotor adaptation that often seem in conflict. We conclude by explaining how this more nuanced understanding of errors and learning processes could lend itself to the analysis of other types of sensorimotor adaptation, of motor skill learning, of the neural processing underlying sensorimotor adaptation in humans, of animal models and of brain computer interfaces.

scholarly journals Sensorimotor adaptation error signals are derived from realistic predictions of movement outcomes

2011 ◽  
Vol 105 (3) ◽  
pp. 1130-1140 ◽  
Author(s):  
Aaron L. Wong ◽  
Mark Shelhamer
Keyword(s):  
Human Subjects ◽  
Motor Command ◽  
Neural Systems ◽  
Error Signal ◽  
The Difference ◽  
Motor Outcomes ◽  
Saccade Adaptation ◽  
Visual Error ◽  
Realistic Prediction ◽  
Adaptation Task

Neural systems that control movement maintain accuracy by adaptively altering motor commands in response to errors. It is often assumed that the error signal that drives adaptation is equivalent to the sensory error observed at the conclusion of a movement; for saccades, this is typically the visual (retinal) error. However, we instead propose that the adaptation error signal is derived as the difference between the observed visual error and a realistic prediction of movement outcome. Using a modified saccade-adaptation task in human subjects, we precisely controlled the amount of error experienced at the conclusion of a movement by back-stepping the target so that the saccade is hypometric (positive retinal error), but less hypometric than if the target had not moved (smaller retinal error than expected). This separates prediction error from both visual errors and motor corrections. Despite positive visual errors and forward-directed motor corrections, we found an adaptive decrease in saccade amplitudes, a finding that is well-explained by the employment of a prediction-based error signal. Furthermore, adaptive changes in movement size were linearly correlated to the disparity between the predicted and observed movement outcomes, in agreement with the forward-model hypothesis of motor learning, which states that adaptation error signals incorporate predictions of motor outcomes computed using a copy of the motor command (efference copy).

Saccadic Gain Modification: Visual Error Drives Motor Adaptation

1998 ◽  
Vol 80 (5) ◽  
pp. 2405-2416 ◽  
Author(s):  
Josh Wallman ◽  
Albert F. Fuchs
Keyword(s):  
Target Location ◽  
Rhesus Macaques ◽  
Motor Adaptation ◽  
Saccadic Eye Movements ◽  
Target Distance ◽  
Error Signal ◽  
Gain Adaptation ◽  
Horizontal Saccade ◽  
Corrective Saccades ◽  
Visual Error

Wallman, Josh and Albert F. Fuchs. Saccadic gain modification: visual error drives motor adaptation. J. Neurophysiol. 80: 2405–2416, 1998. The brain maintains the accuracy of saccadic eye movements by adjusting saccadic amplitude relative to the target distance (i.e., saccade gain) on the basis of the performance of recent saccades. If an experimenter surreptitiously moves the target backward during each saccade, thereby causing the eyes to land beyond their targets, saccades undergo a gradual gain reduction. The error signal driving this conventional saccadic gain adaptation could be either visual (the postsaccadic distance of the target from the fovea) or motoric (the direction and size of the corrective saccade that brings the eye onto the back-stepped target). Similarly, the adaptation itself might be a motor adjustment (change in the size of saccade for a given perceived target distance) or a visual remapping (change in the perceived target distance). We studied these possibilities in experiments both with rhesus macaques and with humans. To test whether the error signal is motoric, we used a paradigm devised by Heiner Deubel. The Deubel paradigm differed from the conventional adaptation paradigm in that the backward step that occurred during the saccade was brief, and the target then returned to its original displaced location. This ploy replaced most of the usual backward corrective saccades with forward ones. Nevertheless, saccadic gain gradually decreased over hundreds of trials. Therefore, we conclude that the direction of saccadic gain adaptation is not determined by the direction of corrective saccades. To test whether gain adaptation is a manifestation of a static visual remapping, we decreased the gain of 10° horizontal saccades by conventional adaptation and then tested the gain to targets appearing at retinal locations unused during adaptation. To make the target appear in such “virgin territory,” we had it jump first vertically and then 10° horizontally; both jumps were completed and the target spot extinguished before saccades were made sequentially to the remembered target locations. Conventional adaptation decreased the gain of the second, horizontal saccade even though the target was in a nonadapted retinal location. In contrast, the horizontal component of oblique saccades made directly to the same virgin location showed much less gain decrease, suggesting that the adaptation is specific to saccade direction rather than to target location. Thus visual remapping cannot account for the entire reduction of saccadic gain. We conclude that saccadic gain adaptation involves an error signal that is primarily visual, not motor, but that the adaptation itself is primarily motor, not visual.

scholarly journals Optimal minimax rates against non-smooth alternatives

2021 ◽  
Author(s):  
Kohtaro Hitomi ◽  
Masamune Iwasawa ◽  
Yoshihiko Nishiyama
Keyword(s):  
Alternative Hypothesis ◽  
Error Variance ◽  
Smooth Functions ◽  
Engel Curves ◽  
Minimax Rates ◽  
Instrumental Variable Regression ◽  
Bounded Functions ◽  
The Difference ◽  
Set Up ◽  
Minimax Rate

Abstract This study investigates optimal minimax rates for specification testing when the alternative hypothesis is built on a set of non-smooth functions. The set consists of bounded functions that are not necessarily differentiable with no smoothness constraints imposed on their derivatives. In the instrumental variable regression set up with an unknown error variance structure, we find that the optimal minimax rate is n−1/4, where n is the sample size. The rate is achieved by a simple test based on the difference between non-parametric and parametric variance estimators. Simulation studies illustrate that the test has reasonable power against various non-smooth alternatives. The empirical application to Engel curves specification emphasizes the good applicability of the test.

scholarly journals THE EFFECT OF BLINDFOLD GAME ON STUDENTS’ VOCABULARY ACHIEVEMENT AT SMP NEGERI 13 KENDARI

2020 ◽  
Vol 5 (3) ◽  
pp. 200
Author(s):  
Andi An-Nisaa Arfin ◽  
Kamaluddin Kamaluddin ◽  
Wa Ode Fatmawati
Keyword(s):  
Junior High School ◽  
Alternative Hypothesis ◽  
First Grade ◽  
First Year ◽  
First Year Students ◽  
Comparison Research ◽  
Significant Difference ◽  
Post Test ◽  
The Difference ◽  
Vocabulary Achievement

The purpose of conducting this research is to examine the difference NGain scores between students who learn vocabulary with Blindfold Game and students who learn vocabulary without Blindfold Game at the first year students of SMP Negeri 13 Kendari. The samples of this research are the first grade four (VII-4) and the first grade three (VII-3) which consists of 27 students for each class. This research is conducted in comparison research design that consists of experimental class (VII-4) and controll class (VII-3). The data of this research are collected by giving pre-test and post-test in two classes (VII-4 & VII-3). The result shows that there is an improvement of the students’ vocabulary achievement. Independent samples t-test shows that, there is a significant difference in the Ngain scores for experimental class ( M = 60.08,  SD = 9.36 ) and controll class ( M = 20.41, SD = 14.56 ), t (52) = 11.904, p (0.000) < 0.05. Therefore, it can be concluded that the value of Sig (2 tailed) is lower than the significance α value (0.000 < 0.05). In other words, alternative hypothesis (H1) is accepted and the null hypothesis (H0) is rejected. It means that the Blindfold game can enrich students’ vocabulary achievement for Junior High School Student.

scholarly journals Visuomotor Learning Generalizes Between Bilateral and Unilateral Conditions Despite Varying Degrees of Bilateral Interference

2010 ◽  
Vol 104 (6) ◽  
pp. 2913-2921 ◽  
Author(s):  
Jinsung Wang ◽  
J. Toby Mordkoff ◽  
Robert L. Sainburg
Keyword(s):  
Arm Movement ◽  
Visuomotor Adaptation ◽  
Sensorimotor Adaptation ◽  
Visuomotor Learning ◽  
Motion Direction ◽  
Visual Rotation ◽  
Hand Motion ◽  
Bimanual Performance ◽  
Affect Transfer ◽  
Unilateral Conditions

Bilateral interference, referring to the tendency of movements of one arm to disrupt the intended movements made simultaneously with the other arm, is often observed in a task that involves differential planning of each arm movement during sensorimotor adaptation. In the present study, we examined two questions: 1) how does the compatibility between visuomotor adaptation tasks performed with both arms affect bilateral interference during bimanual performance? and 2) how do variations in bilateral interference affect transfer of visuomotor adaptation between bilateral and unilateral conditions? To examine these questions, we manipulated visuomotor compatibility using two kinematic variables (direction of required hand motion, direction of an imposed visual rotation). Experiment 1 consisted of two conditions in which the direction of visual rotations for both arms was either in the same or opposing directions, whereas the target direction for both arms was always the same. In experiment 2, we examined the pattern of generalization between the bilateral and unilateral conditions when both the target and rotation directions were opposing between the arms. In both experiments, subjects first adapted to a 30° visual rotation with one arm (preunilateral), then with both arms (bilateral), and finally with the arm that was not used in the first session (postunilateral). Our results show that bilateral interference was smallest when both variables were the same between the arms. Our data also show extensive transfer of visuomotor adaptation between bilateral and unilateral conditions, regardless of degree of bilateral interference.

A phrenic nerve-actuated electronically controlled positive-pressure ventilator

1987 ◽  
Vol 62 (5) ◽  
pp. 2121-2125 ◽  
Author(s):  
E. R. Schertel ◽  
D. A. Schneider ◽  
D. L. Howard ◽  
J. F. Green
Keyword(s):  
Moving Average ◽  
Inspiratory Flow ◽  
Positive Pressure ◽  
Feedback Signal ◽  
Position Signal ◽  
Tracheal Pressure ◽  
Valve Position ◽  
Air Valve ◽  
The Difference ◽  
Operational Modes

We have constructed an electronically controlled positive-pressure ventilator actuated by phrenic neural activity for use in open-chested or paralyzed experimental animals for the study of breathing pattern. A Bird Mark 14 positive-pressure ventilator was modified such that flow is a linear function of a command signal. Flow is delivered by advancing an air valve with a servo-motor that is controlled by one of three different operational modes. In two of the modes, the difference between the electronic average of inspiratory phrenic activity (moving average) and a feedback signal determines the inspiratory flow. The feedback signal is derived from either tracheal pressure or an electronic measure of inspired volume. In the third mode, the moving average is differentiated to provide control of inspiratory flow and volume. Physiological flow profiles were created using all three operational modes. Integration of an air-valve position signal provides an electronic measure of tidal volume. An additional feature of this ventilator allows inspiratory flow and duration to be predetermined for a given breath.

scholarly journals Can patients with cerebellar disease switch learning mechanisms to reduce their adaptation deficits?

Brain ◽  
2019 ◽  
Vol 142 (3) ◽  
pp. 662-673 ◽  
Author(s):  
Aaron L Wong ◽  
Cherie L Marvel ◽  
Jordan A Taylor ◽  
John W Krakauer
Keyword(s):  
Prediction Error ◽  
Poor Performance ◽  
Visuomotor Adaptation ◽  
Cerebellar Degeneration ◽  
Prediction Errors ◽  
Cerebellar Disease ◽  
Learning Mechanisms ◽  
Visuomotor Rotation ◽  
Age Related ◽  
Sensory Prediction

Abstract Systematic perturbations in motor adaptation tasks are primarily countered by learning from sensory-prediction errors, with secondary contributions from other learning processes. Despite the availability of these additional processes, particularly the use of explicit re-aiming to counteract observed target errors, patients with cerebellar degeneration are surprisingly unable to compensate for their sensory-prediction error deficits by spontaneously switching to another learning mechanism. We hypothesized that if the nature of the task was changed—by allowing vision of the hand, which eliminates sensory-prediction errors—patients could be induced to preferentially adopt aiming strategies to solve visuomotor rotations. To test this, we first developed a novel visuomotor rotation paradigm that provides participants with vision of their hand in addition to the cursor, effectively setting the sensory-prediction error signal to zero. We demonstrated in younger healthy control subjects that this promotes a switch to strategic re-aiming based on target errors. We then showed that with vision of the hand, patients with cerebellar degeneration could also switch to an aiming strategy in response to visuomotor rotations, performing similarly to age-matched participants (older controls). Moreover, patients could retrieve their learned aiming solution after vision of the hand was removed (although they could not improve beyond what they retrieved), and retain it for at least 1 year. Both patients and older controls, however, exhibited impaired overall adaptation performance compared to younger healthy controls (age 18–33 years), likely due to age-related reductions in spatial and working memory. Patients also failed to generalize, i.e. they were unable to adopt analogous aiming strategies in response to novel rotations. Hence, there appears to be an inescapable obligatory dependence on sensory-prediction error-based learning—even when this system is impaired in patients with cerebellar disease. The persistence of sensory-prediction error-based learning effectively suppresses a switch to target error-based learning, which perhaps explains the unexpectedly poor performance by patients with cerebellar degeneration in visuomotor adaptation tasks.

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