scholarly journals Pupil-linked arousal modulates trial-by-trial motor adaptation in humans

2021 ◽  
Author(s):  
Atsushi Yokoi ◽  
Jeff Weiler
Keyword(s):  
Motor Learning ◽  
Force Field ◽  
Learning Rate ◽  
Sudden Increase ◽  
Rapid Reduction ◽  
Non Invasive ◽  
Arousal System ◽  
Series Of Experiments ◽  
The Rich ◽  
Task Irrelevant

Research in reward-based decision-making showed that humans and animals dynamically modulate learning rate according to their belief about environmental change (volatility) and surprise about observation. Recent evidence also suggests that neuromodulator noradrenaline (NA) signals volatility and surprise. Despite the rich anatomical evidence suggesting the potential influence of NA on the motor system, it is still elusive how NA and volatility/surprise affect human motor learning. To address this issue, we ran a series of experiments in which we simultaneously tracked the pupil diameter, a non-invasive proxy for the central NA/arousal activity, during a short-term force-field reach adaptation paradigm. A sudden increase in error due to the force-field resulted in increased pupil dilation during movement followed by an elevated baseline diameter in the following trials. These online and offline pupil responses showed a consistent pattern with surprise and volatility simulated by a recent computational model which dynamically adjusts learning rate according to volatility estimated from experienced error (surprise). However, unlike the model's prediction, when participants experienced frequent reversals in force-field, the size of pupil responses rapidly diminished regardless of large errors induced by reversals. We further confirmed that the causal manipulation of participants' arousal by task-irrelevant auditory stimuli modulated the single-trial motor learning rate. Collectively, these results provide a compelling evidence that NA/arousal system acts as a common modulator of learning rate in both cognitive and motor domains. Rapid reduction in pupil responses at reversals suggests that error sensitivity for computing current environmental uncertainty and surprise is also highly dynamic.

scholarly journals Motor learning in reaching tasks leads to homogenization of task space error distribution

2021 ◽  
Author(s):  
Puneet Singh ◽  
Oishee Ghosal ◽  
Aditya Murthy ◽  
Ashitava Ghodal
Keyword(s):  
Motor Learning ◽  
Force Field ◽  
Error Distribution ◽  
Task Space ◽  
Field Perturbation ◽  
Directional Dependence ◽  
Reaching Tasks ◽  
Space Error ◽  
Human Arm ◽  
Point To Point

A human arm, up to the wrist, is often modelled as a redundant 7 degree-of-freedom serial robot. Despite its inherent nonlinearity, we can perform point-to-point reaching tasks reasonably fast and with reasonable accuracy in the presence of external disturbances and noise. In this work, we take a closer look at the task space error during point-to-point reaching tasks and learning during an external force-field perturbation. From experiments and quantitative data, we confirm a directional dependence of the peak task space error with certain directions showing larger errors than others at the start of a force-field perturbation, and the larger errors are reduced with repeated trials implying learning. The analysis of the experimental data further shows that a) the distribution of the peak error is made more uniform across directions with trials and the error magnitude and distribution approaches the value when no perturbation is applied, b) the redundancy present in the human arm is used more in the direction of the larger error, and c) homogenization of the error distribution is not seen when the reaching task is performed with the non-dominant hand. The results support the hypothesis that not only magnitude of task space error, but the directional dependence is reduced during motor learning and the workspace is homogenized possibly to increase the control efficiency and accuracy in point-to-point reaching tasks. The results also imply that redundancy in the arm is used to homogenize the workspace, and additionally since the bio-mechanically similar dominant and non-dominant arms show different behaviours, the homogenizing is actively done in the central nervous system.

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.

Comparative Spectroscopic Analysis of Maya Wall Paintings from Ek’Balam, Mexico

2014 ◽  
Vol 1618 ◽  
pp. 63-72 ◽  
Author(s):  
A. Alonso ◽  
N. A. Pérez ◽  
J. L. Ruvalcaba Sil ◽  
E. Casanova ◽  
P. Claes ◽  
...  
Keyword(s):  
Spectroscopic Analysis ◽  
Analytical Techniques ◽  
Archaeological Site ◽  
X Ray Diffraction ◽  
X Ray ◽  
Non Invasive ◽  
Yellow Orange ◽  
Pigment Distribution ◽  
The Rich ◽  
Invasive Techniques

ABSTRACTThe Maya archaeological site of Ek’Balam is located in Yucatán, Mexico. This place is known for its artistic tradition of reliefs modeled in stucco as well as the rich pictorial and hieroglyphic texts. Although the mural played a key role in the artistic program architectural of elite groups, most of these remains have not been studied, either by its incomplete or fragile condition, or by localization in inaccessible substructures.In this study, technical aspects of the mural paintings from rooms 12 and 50 of the main building of the site are addressed by the spectroscopic analysis of its materials. Optical microscopy was used to observe the layers superposition and pigment distribution, while the stucco and rock support were characterized by X-ray Diffraction (XRD) and X-ray Fluorescence (XRF). Moreover, the chromatic palette composed of different colors and tones of red, yellow, orange, green, blue and black were analyzed mainly with non-invasive techniques using Raman and FTIR spectroscopies as well as XRF.The information obtained from the combination of these analytical techniques, allowed a better understanding of the similarities and differences between these two rooms that were built during the last construction stage of the Acropolis. These results were also compared with previous analyses of mural painting of this site and other Maya paintings.

scholarly journals Cerebellar motor learning: are environment dynamics more important than error size?

2013 ◽  
Vol 110 (2) ◽  
pp. 322-333 ◽  
Author(s):  
Tricia L. Gibo ◽  
Sarah E. Criscimagna-Hemminger ◽  
Allison M. Okamura ◽  
Amy J. Bastian
Keyword(s):  
Motor Learning ◽  
Force Field ◽  
Complex Dynamics ◽  
External Perturbation ◽  
Joint Space ◽  
Relative Effect ◽  
Small Error ◽  
Cerebellar Damage ◽  
Movement Dynamics ◽  
Compensatory Strategy

Cerebellar damage impairs the control of complex dynamics during reaching movements. It also impairs learning of predictable dynamic perturbations through an error-based process. Prior work suggests that there are distinct neural mechanisms involved in error-based learning that depend on the size of error experienced. This is based, in part, on the observation that people with cerebellar degeneration may have an intact ability to learn from small errors. Here we studied the relative effect of specific dynamic perturbations and error size on motor learning of a reaching movement in patients with cerebellar damage. We also studied generalization of learning within different coordinate systems (hand vs. joint space). Contrary to our expectation, we found that error size did not alter cerebellar patients' ability to learn the force field. Instead, the direction of the force field affected patients' ability to learn, regardless of whether the force perturbations were introduced gradually (small error) or abruptly (large error). Patients performed best in fields that helped them compensate for movement dynamics associated with reaching. However, they showed much more limited generalization patterns than control subjects, indicating that patients rely on a different learning mechanism. We suggest that patients typically use a compensatory strategy to counteract movement dynamics. They may learn to relax this compensatory strategy when the external perturbation is favorable to counteracting their movement dynamics, and improve reaching performance. Altogether, these findings show that dynamics affect learning in cerebellar patients more than error size.

scholarly journals Successful auditory motor adaptation requires task-relevant auditory errors

2019 ◽  
Vol 122 (2) ◽  
pp. 552-562 ◽  
Author(s):  
Ayoub Daliri ◽  
Jonathan Dittman
Keyword(s):  
Motor Learning ◽  
Categorical Perception ◽  
Production Systems ◽  
State Space Model ◽  
Motor Adaptation ◽  
Auditory Information ◽  
Speech Motor Learning ◽  
Task Irrelevant ◽  
The Brain ◽  
Speech Motor

When we produce speech movements, we also predict the auditory consequences of the movements. We use discrepancies between our predictions and incoming auditory information to modify our future movements (adapt). Although auditory errors are crucial for speech motor learning, not all perceived auditory errors are consequences of our own actions. Therefore, the brain needs to evaluate the relevance of perceived auditory errors. In this study, we examined error assessment processes involved in auditory motor adaptation by systematically manipulating the correspondence between speech motor outputs and their auditory consequences during speaking. Participants ( n = 30) produced speech while they received perturbed auditory feedback (e.g., produced “head” but heard a word that sounded like “had”). In one condition, auditory errors were related to participants’ productions (task-relevant errors). In another condition, auditory errors were defined by the experimenter and had no correspondence with participants’ speech output (task-irrelevant errors). We found that the extent of adaptation and error sensitivity (derived from a state-space model) were greater in the condition with task-relevant auditory errors compared with those in the condition with task-irrelevant auditory errors. Additionally, participants with smaller perceptual targets (derived from a categorical perception task) adapted more to auditory perturbations, and participants with larger perceptual targets adapted less. Similarly, participants with smaller perceptual targets were more sensitive to errors in the condition with task-relevant auditory errors. Together, our results highlight the intricate mechanisms, involving both perception and production systems, that the brain uses to optimally integrate auditory errors for successful speech motor learning. NEW & NOTEWORTHY Feedback monitoring is essential for accurate speech production. By providing empirical results and a computational framework, we show that 1) the brain evaluates relevance of auditory errors and responds more to relevant errors, and 2) smaller perceptual targets are associated with more sensitivity to errors and more auditory motor adaptation.

scholarly journals Plastic Changes in Hand Proprioception Following Force-Field Motor Learning

2010 ◽  
Vol 104 (3) ◽  
pp. 1213-1215 ◽  
Author(s):  
Daniel J. Goble ◽  
Joaquin A. Anguera
Keyword(s):  
Motor Learning ◽  
Force Field ◽  
Recent Work ◽  
Recent Article ◽  
Sensory Feedback ◽  
Motor Output ◽  
Feedback Processing ◽  
Plastic Changes ◽  
Proprioceptive Function ◽  
New Evidence

Motor neurophysiologists are placing greater emphasis on sensory feedback processing than ever before. In line with this shift, a recent article by Ostry and colleagues provided timely new evidence that force-field motor learning influences not only motor output, but also proprioceptive sense. In this Neuro Forum, the merits and limitations of Ostry and colleagues are explored in the context of recent work on proprioceptive function, including several recent studies from this journal.

scholarly journals Motor learning and its sensory effects: time course of perceptual change and its presence with gradual introduction of load

2013 ◽  
Vol 109 (3) ◽  
pp. 782-791 ◽  
Author(s):  
Andrew A. G. Mattar ◽  
Mohammad Darainy ◽  
David J. Ostry
Keyword(s):  
Motor Learning ◽  
Force Field ◽  
Motor Performance ◽  
Time Course ◽  
Sensory Perception ◽  
Learning Task ◽  
Perceptual Change ◽  
Sensory Effects ◽  
Gradual Introduction ◽  
Lateral Displacements

A complex interplay has been demonstrated between motor and sensory systems. We showed recently that motor learning leads to changes in the sensed position of the limb (Ostry DJ, Darainy M, Mattar AA, Wong J, Gribble PL. J Neurosci 30: 5384–5393, 2010). Here, we document further the links between motor learning and changes in somatosensory perception. To study motor learning, we used a force field paradigm in which subjects learn to compensate for forces applied to the hand by a robotic device. We used a task in which subjects judge lateral displacements of the hand to study somatosensory perception. In a first experiment, we divided the motor learning task into incremental phases and tracked sensory perception throughout. We found that changes in perception occurred at a slower rate than changes in motor performance. A second experiment tested whether awareness of the motor learning process is necessary for perceptual change. In this experiment, subjects were exposed to a force field that grew gradually in strength. We found that the shift in sensory perception occurred even when awareness of motor learning was reduced. These experiments argue for a link between motor learning and changes in somatosensory perception, and they are consistent with the idea that motor learning drives sensory change.

Perceptuo-motor learning rate declines by half from 20s to 70/80s

2012 ◽  
Vol 225 (1) ◽  
pp. 75-84 ◽  
Author(s):  
Rachel O. Coats ◽  
Winona Snapp-Childs ◽  
Andrew D. Wilson ◽  
Geoffrey P. Bingham
Keyword(s):  
Motor Learning ◽  
Learning Rate
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