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 Feedback adaptation to unpredictable force fields in 250ms

2019 ◽  
Author(s):  
Frédéric Crevecoeur ◽  
James Mathew ◽  
Marie Bastin ◽  
Philippe Lefevre
Keyword(s):  
Nervous System ◽  
Motor Learning ◽  
Force Field ◽  
Recent Work ◽  
Muscle Activity ◽  
Force Fields ◽  
Control Strategies ◽  
Motor Adaptation ◽  
Classical Studies ◽  
Learning And Adaptation

AbstractMotor learning and adaptation are important functions of the nervous system. Classical studies have characterized how humans adapt to changes in the environment during tasks such as reaching, and have documented improvements in behavior across movements. Yet little is known about how quickly the nervous system adapts to such disturbances. In particular, recent work has suggested that adaptation could be sufficiently fast to alter the control strategies of an ongoing movement. To further address the possibility that learning occurred within a single movement, we designed a series of human reaching experiments to extract in muscles recordings the latency of feedback adaptation. Our results confirmed that participants adapted their feedback responses to unanticipated force fields applied randomly. In addition, our analyses revealed that the feedback response was specifically and finely tuned to the ongoing perturbation not only across trials with the same force field, but also across different kinds of force fields. Finally, changes in muscle activity consistent with feedback adaptation occurred in about 250ms following reach onset. We submit this estimate as the latency of motor adaptation in the nervous system.

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.

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 New Light on the Historia Augusta

2020 ◽  
Vol 110 ◽  
pp. 167-198
Author(s):  
Justin Stover
Keyword(s):  
Recent Work ◽  
Historia Augusta ◽  
New Evidence

AbstractThis paper presents a new manuscript of part of the Historia Augusta from Erlangen, which vindicates a more than century-old hypothesis by E. Patzig: that the 1489 Venice edition of the work is textually valuable. On this basis, and building on the recent work of R. Modonutti, I present five new passages that are not printed in modern editions of the HA, six lacunose passages restored, and propose that the lost Murbach manuscript is the source. Armed with this new evidence, I re-examine the question of the great lacuna between the Lives of Maximus and Balbinus and the Lives of the Two Valerians, showing that it is a codicological — and not authorial — feature.

Colored context cues can facilitate the ability to learn and to switch between multiple dynamical force fields

2011 ◽  
Vol 106 (1) ◽  
pp. 163-183 ◽  
Author(s):  
Touria Addou ◽  
Nedialko Krouchev ◽  
John F. Kalaska
Keyword(s):  
Force Field ◽  
Color Change ◽  
Force Fields ◽  
Human Subjects ◽  
Elbow Flexion ◽  
Motor Output ◽  
Viscous Force ◽  
Dynamic Force ◽  
Flexion Extension ◽  
Context Cues

We tested the efficacy of color context cues during adaptation to dynamic force fields. Four groups of human subjects performed elbow flexion/extension movements to move a cursor between targets on a monitor while encountering a resistive (Vr) or assistive (Va) viscous force field. They performed two training sets of 256 trials daily, for 10 days. The monitor background color changed (red, green) every four successful trials but provided different degrees of force field context information to each group. For the irrelevant-cue groups, the color changed every four trials, but one group encountered only the Va field and the other only the Vr field. For the reliable-cue group, the force field alternated between Va and Vr each time the monitor changed color (Vr, red; Va, green). For the unreliable-cue group, the force field changed between Va and Vr pseudorandomly at each color change. All subjects made increasingly stereotyped movements over 10 training days. Reliable-cue subjects typically learned the association between color cues and fields and began to make predictive changes in motor output at each color change during the first day. Their performance continued to improve over the remaining days. Unreliable-cue subjects also improved their performance across training days but developed a strategy of probing the nature of the field at each color change by emitting a default motor response and then adjusting their motor output in subsequent trials. These findings show that subjects can extract explicit and implicit information from color context cues during force field adaptation.

Athens and Tenos in the Early Hellenistic Age

1992 ◽  
Vol 42 (2) ◽  
pp. 365-383 ◽  
Author(s):  
Gary Reger
Keyword(s):  
Recent Work ◽  
Third Century ◽  
The Third ◽  
Greek History ◽  
History Of ◽  
Old Evidence ◽  
New Evidence ◽  
Standing Problem

Some recent work on the history of Athens and Tenos in the third century B.c. has brought to light new evidence and new interpretations of old evidence for this notoriously shadowy period of Greek history. Reflection on this material has suggested to me solutions to a few minor puzzles (Sections IA, IB, III), a contribution to a long-standing problem in the history of Athens in the early third century (Section IB), and a new explanation for the entry of Rhodos into the war with Antiokhos (Section II).

Time, Death, and the Next Generation: The Early Elizabethan Recusancy Policy, 1558–1574

1982 ◽  
Vol 14 (2) ◽  
pp. 103-117
Author(s):  
John J. LaRocca
Keyword(s):  
Recent Work ◽  
Recent Article ◽  
Local Level ◽  
The Political ◽  
Privy Council ◽  
Next Generation ◽  
Social Composition ◽  
The Social ◽  
International Character ◽  
The Church

In a recent article, Caroline M. Hibbard noted that recent work on Tudor-Stuart recusancy has focused on the enforcement of royal and statutory policy on the local level and has examined the social composition of the recusant community. These studies have revealed that the recusant community was not dominated by priests, not subject to the political directives of the papacy, and not plotting rebellion. The problem inherent in these local studies, as Professor Hibbard points out, is that they do not explain why the English were anti-Catholic and they do not examine the international character of the English Catholic Community. This article is an attempt to view the recusant problem from the perspective of the monarch and the privy council, because both monarch and privy council were aware of the international character of Catholicism and both stated clearly in their policies toward recusants the grounds of their objection to the Catholic community. An analysis of the recusancy policy established by Elizabeth between 1559 and 1574 reveals that her primary objection to the recusants was not religious but political. The recusants denied a fundamental claim of the monarch: the headship of the church and, therefore, the claim that the monarch was the source of all power within the realm. This article, then, will examine the ways in which she wished to contain a minority who denied her supreme power in the realm and the circumstances which caused the queen and the council to change that policy.

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.

The Compromise of Charles Cardinal de Lorraine: New Evidence

2003 ◽  
Vol 54 (3) ◽  
pp. 469-483 ◽  
Author(s):  
STUART CARROLL
Keyword(s):  
Recent Work ◽  
Reform Movement ◽  
Privy Council ◽  
Before And After ◽  
New Evidence

The discovery of a document, until now hidden in an obscure Protestant pamphlet, presented by Charles cardinal de Lorraine (1525–74) to the privy council in August 1562, underpins recent work which shows the cardinal to have been an evangelical Catholic interested in reform and in reconciliation with Lutherans, both before and after the Colloquy of Poissy. This paper argues that Protestants feared Lorraine precisely because his interest in dialogue had the potential to split the reform movement. Publication of his five articles in 1565 was an attempt to embarrass him after Trent and to compromise his political rapprochement with the prince of Condé.

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