scholarly journals Aging Does Not Affect Beta Modulation during Reaching Movements

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Serena Ricci ◽  
Ramtin Mehraram ◽  
Elisa Tatti ◽  
Aaron B. Nelson ◽  
Martina Bossini-Baroggi ◽  
...  
Keyword(s):  
Modulation Depth ◽  
Movement Time ◽  
Peak Latency ◽  
Reaching Movements ◽  
Performance Indices ◽  
Reaching Task ◽  
Beta Power ◽  
Total Movement ◽  
Older Subjects ◽  
Highly Correlated

During movement, modulation of beta power occurs over the sensorimotor areas, with a decrease just before its start (event-related desynchronization, ERD) and a rebound after its end (event-related synchronization, ERS). We have recently found that the depth of ERD-to-ERS modulation increases during practice in a reaching task and the following day decreases to baseline levels. Importantly, the magnitude of the beta modulation increase during practice is highly correlated with the retention of motor skill tested the following day. Together with other evidence, this suggests that the increase of practice-related modulation depth may be the expression of sensorimotor cortex’s plasticity. Here, we determine whether the practice-related increase of beta modulation depth is equally present in a group of younger and a group of older subjects during the performance of a 30-minute block of reaching movements. We focused our analyses on two regions of interest (ROIs): the left sensorimotor and the frontal region. Performance indices were significantly different in the two groups, with the movements of older subjects being slower and less accurate. Importantly, both groups presented a similar increase of the practice-related beta modulation depth in both ROIs in the course of the task. Peak latency analysis revealed a progressive delay of the ERS peak that correlated with the total movement time. Altogether, these findings support the notion that the depth of beta modulation in a reaching movement task does not depend on age and confirm previous findings that only ERS peak latency but not ERS magnitude is related to performance indices.

scholarly journals Motor Cortical Representation of Position and Velocity During Reaching

2007 ◽  
Vol 97 (6) ◽  
pp. 4258-4270 ◽  
Author(s):  
Wei Wang ◽  
Sherwin S. Chan ◽  
Dustin A. Heldman ◽  
Daniel W. Moran
Keyword(s):  
Neural Activity ◽  
Cortical Neurons ◽  
Three Dimensional ◽  
Reaching Movements ◽  
Hand Position ◽  
Cortical Representation ◽  
Reaching Task ◽  
Position Signal ◽  
Motor Cortical ◽  
Highly Correlated

This study examines motor cortical representation of hand position and its relationship to the representation of hand velocity during reaching movements. In all, 978 motor cortical neurons were recorded from the proximal arm area of rostral motor cortex. The results demonstrate that position and velocity are simultaneously encoded by single motor cortical neurons in an additive fashion and that the relative weights of the position and velocity signals change dynamically during reaching. The two variables—hand position and hand velocity—are highly correlated in the standard center-out reaching task. A new reaching task (standard reaching) is introduced to minimize these correlations. Likewise, a new decoding method (indirect OLE) was developed to analyze the data by simultaneously decoding both three-dimensional (3D) hand position and 3D hand velocity from correlated neural activity. This method shows that, on average, the reconstructed velocity led the actual hand velocity by 122 ms, whereas the reconstructed position signal led the actual hand position by 81 ms.

Application of Virtual Environments to Assessment of Human Motor Learning During Reaching Movements

2009 ◽  
Vol 18 (2) ◽  
pp. 112-124 ◽  
Author(s):  
Ali Asadi Nikooyan ◽  
Amir Abbas Zadpoor
Keyword(s):  
Force Field ◽  
Force Fields ◽  
Physical World ◽  
Reaching Movements ◽  
Viscous Force ◽  
Virtual Object ◽  
Learning Mechanisms ◽  
Reaching Task ◽  
Third Phase ◽  
Virtual Force

This paper studies learning of reaching movements in a dynamically variable virtual environment specially designed for this purpose. Learning of reaching movements in the physical world has been extensively studied by several researchers. In most of those studies, the subjects are asked to exercise reaching movements while being exposed to real force fields exerted through a robotic manipulandum. Those studies have contributed to our understanding of the mechanisms used by the human cognitive system to learn reaching movements in the physical world. The question that remains to be answered is how the learning mechanism in the physical world relates to its counterpart in the virtual world where the real force fields are replaced by virtual force fields. A limited number of studies have already addressed this question and have shown that there are, actually, quite a number of relationships between the learning mechanisms in these two different environments. In this study, we are focused on gaining a more in-depth understanding of these relationships. In our experiments, the subjects are asked to guide a virtual object to a desired target on a computer screen using a mouse. The movement of the virtual object is affected by a viscous virtual force field that is sensed by the examinees through their visual system. Three groups of examinees are used for the experiments. All the examinees are first trained in the null-field condition. Then, the viscous force field is introduced either suddenly (for the two first groups) or gradually (for the last group). While the first and third groups of the examinees used their dominant arm to guide the virtual object in the second step, the second group used their nondominant arm. Generalization of the learning from the dominant to the nondominant arm and vice versa was studied in the third phase of the experiments. Finally, the force field was removed and the examinees were asked to repeat the reaching task to study the so-called aftereffects phenomenon. The results of the experiments are compared with the studies performed in the physical world. It is shown that the trends of learning and generalization are similar to what is observed in the physical world for a sudden application of the virtual force field. However, the generalization behavior of the examinees is somewhat different from the physical world if the force field is gradually applied.

Investigating the Difficulty of One Degree of Freedom Positioning: Associating Movement Phases with Regions

2009 ◽  
Vol 53 (15) ◽  
pp. 965-969 ◽  
Author(s):  
Robert Pastel
Keyword(s):  
Movement Time ◽  
Touch Screen ◽  
Degree Of Freedom ◽  
One Dimension ◽  
Mouse Button ◽  
Total Movement ◽  
Remaining Time ◽  
Total Movement Time

Positioning an object within specified bounds is a common daily computer task, for example making selections using a touch screen or positioning icons relative to each other. This experiment measured times for participants ( n = 145) to position rectangular cursors with various widths, p, within rectangular targets with various tolerances, t, in one dimension. The analysis divides the total movement time into three parts, the time for the cursor to touch the target, the time to enter the target after touching, and the centering time, the remaining time for participants to indicate that the cursor is completely within the target by clicking on the mouse button. The time to touch the target was modeled well by the initial cursor-target separation, r2/sup> = 0.95. The entering time was modeled well by log2( p/t + 1), r2/sup> = 0.99, and the centering time was modeled well by r2/sup> = 0.94

rTMS of Medial Parieto-occipital Cortex Interferes with Attentional Reorienting during Attention and Reaching Tasks

2013 ◽  
Vol 25 (9) ◽  
pp. 1453-1462 ◽  
Author(s):  
Marco Ciavarro ◽  
Ettore Ambrosini ◽  
Annalisa Tosoni ◽  
Giorgia Committeri ◽  
Patrizia Fattori ◽  
...  
Keyword(s):  
Posterior Parietal Cortex ◽  
Motor Planning ◽  
Occipital Cortex ◽  
Reaching Movements ◽  
Dorsal Part ◽  
Visual Stream ◽  
Reaching Task ◽  
On Line ◽  
Posterior Parietal

Unexpected changes in the location of a target for an upcoming action require both attentional reorienting and motor planning update. In both macaque and human brain, the medial posterior parietal cortex is involved in both phenomena but its causal role is still unclear. Here we used on-line rTMS over the putative human V6A (pV6A), a reach-related region in the dorsal part of the anterior bank of the parieto-occipital sulcus, during an attention and a reaching task requiring covert shifts of attention and planning of reaching movements toward cued targets in space. We found that rTMS increased RTs to invalidly cued but not to validly cued targets during both the attention and reaching task. Furthermore, we found that rTMS induced a deviation of reaching endpoints toward visual fixation and that this deviation was larger for invalidly cued targets. The results suggest that reorienting signals are used by human pV6A area to rapidly update the current motor plan or the ongoing action when a behaviorally relevant object unexpectedly occurs in an unattended location. The current findings suggest a direct involvement of the action-related dorso-medial visual stream in attentional reorienting and a more specific role of pV6A area in the dynamic, on-line control of reaching actions.

scholarly journals Saturated Muscle Activation Contributes to Compensatory Reaching Strategies After Stroke

2005 ◽  
Vol 94 (5) ◽  
pp. 2999-3008 ◽  
Author(s):  
Patrick H. McCrea ◽  
Janice J. Eng ◽  
Antony J. Hodgson
Keyword(s):  
Muscle Activation ◽  
Sagittal Plane ◽  
Reaching Movements ◽  
Abduction Angle ◽  
Task Completion ◽  
Shoulder Abduction ◽  
Reaching Task ◽  
Hand Motion ◽  
Control Subjects ◽  
Anterior Deltoid

The control and execution of movement could potentially be altered by the presence of stroke-induced weakness if muscles are incapable of generating sufficient power. The purpose of this study was to identify compensatory strategies during a forward (sagittal) reaching task for 20 persons with chronic stroke and 10 healthy age-matched controls. We hypothesized that the paretic anterior deltoid would be maximally activated (i.e., saturated) during a reaching task and that task completion would require activation of additional muscles, resulting in compensatory movements out of the sagittal plane. For reaching movements by control subjects, joint motion remained largely in the sagittal plane and hand trajectories were smooth and direct. Movement characteristics of the nonparetic arm of stroke subjects were similar to control subjects except for small increases in the abduction angle and the percentage that anterior deltoid was activated. In contrast, reaching movements of the paretic arm of stroke subjects were characterized by increased activation of all muscles, especially the lateral deltoid, in addition to the anterior deltoid, with resulting shoulder abduction power and segmented and indirect hand motion. For the paretic arm of stroke subjects, muscle and kinetic compensations increased with impairment severity and weaker muscles were used at a higher percentage of their available muscle activity. These results suggest that the inability to generate sufficient force with the typical agonists involved during a forward reaching task may necessitate compensatory muscle recruitment strategies to complete the task.

scholarly journals Effects of target location and uncertainty on reaching movements in standing position

2012 ◽  
Vol 26 (3) ◽  
pp. 485-493 ◽  
Author(s):  
Luiz de França Bahia Loureiro Junior ◽  
Sandra Maria Sbeghen Ferreira de Freitas ◽  
Paulo Barbosa de Freitas
Keyword(s):  
Reaction Time ◽  
Target Location ◽  
Movement Time ◽  
Target Position ◽  
Standing Position ◽  
Reaching Movements ◽  
Radial Error ◽  
Arm Reaching ◽  
The Right

The effects of target location and uncertainty of target position on reaching movements while standing were investigated. Ten healthy, right-handed adults stood facing a 17'' touchscreen. They were instructed to press with their right index fingertip a push bottom and touch the center of the target displayed on the screen after it was lighted on, moving quickly their arm. The target was shown either ipsi- or contralateral to the right arm and either in a certain or uncertain position. Reaction time (RT), movement time (MT), and radial error (RE) were assessed. Results revealed shorter RT (≈ 35 ms) and smaller RE (≈ 0.19 cm) for certain than for uncertain condition and slightly longer RT (≈ 8 ms) and MT (≈ 18 ms) for reaches towards the contralateral target. In conclusion, the findings of this study showing the effect of uncertainty of target location as well as target position are also applied to arm reaching in standing position.

scholarly journals Research on the visual cognition patterns of exit guide sign viewing on freeway interchanges

2019 ◽  
Vol 11 (3) ◽  
pp. 168781401881953
Author(s):  
Guichao Ren ◽  
Xiaohua Zhao ◽  
Zhanzhou Lin ◽  
Wenxiang Xu
Keyword(s):  
Eye Movement ◽  
Fixation Duration ◽  
Tracking System ◽  
Movement Time ◽  
Threshold Value ◽  
Visual Cognition ◽  
The Road ◽  
Route Information ◽  
Four Levels ◽  
Highly Correlated

The development of freeway construction and the increasing coverage of the road network have led to increasing requirements for guide signs. This article investigated drivers’ visual cognition pattern regarding exit guide signs on freeway interchanges. A static visual cognition experiment with 32 participants was carried out. The route information volume (four levels) and destination information volume (seven levels) were selected as the variables. An eye-tracking system was utilized to record drivers’ eye movement indicators, such as eye movement time, saccade frequency, seek time, and fixation duration. The results indicated that the eye movement time, saccade frequency, and seek time are highly correlated with information volume and increase significantly with the increases in information volume; although the fixation duration has no correlation with information volume, the fixation duration value, saccade frequency, and seek time of destination information are significantly higher than those of route information, and the destination information fulfills a stronger guiding function during the driver’s trip. The corresponding threshold values of destination information are 5, 5, 4, and 3 under the four levels of route information, and the threshold value of route information is 3.

Information Content and Task Performance: A Study of the Older Worker

1978 ◽  
Vol 22 (1) ◽  
pp. 558-563
Author(s):  
Dev S. Kochhar ◽  
Hatem M. Ali
Keyword(s):  
Decision Making ◽  
Heart Rate ◽  
Movement Time ◽  
Decision Time ◽  
Control Group ◽  
Information Load ◽  
Significant Determinant ◽  
Performance Time ◽  
Older Subjects ◽  
And Task

A study was conducted to investigate the variation in speed of performance and decision making ability with age. Twenty volunteers from local industry formed the subject group. Ten of these ranged in age from 52 to 63 years. The control group ranged in age from 18 to 29 years. The task performed involved decision making hand movement and positioning elements. Three levels of information load (2, 3 and 4 bits), four distances of move (7“, 10”, 13“ and 16”), and four levels of radial clearance (0.008“, 0.063”, 0.25“ and 0.75”) were taken as independent variables. The dependent variable, performance time, was composed of the decision and movement time components (DT and MT). In addition, heart rate was also monitored. It was found that age was a significant determinant of performance time (p ≤ .01). The components of performance time, i.e., decision and movement times were both significantly higher for the older subjects as compared to the younger ones (p ≤ .01) reflecting the fact that there is some natural slowing of psychomotor function with age in such combined manual and decision tasks. The information load and the distance of move were significant determinants of decision time and also of movement time (p < 0.01). The clearance was a significant determinant of movement time (p < 0.01). The difference between the older subjects and the younger subjects in decision time increased with an increase in the information load. An analysis of the performance errors for the self paced task indicated that the slowing among the older subjects was not observed at the expense of accuracy. The study provided no evidence that age has an effect on heart rate variability under different levels of information load and task difficulty.

Evaluation of the Helicopter Emergency Breathing Apparatus on Egress Performance

2020 ◽  
Vol 91 (12) ◽  
pp. 962-965
Author(s):  
Michael King ◽  
Elizabeth Sanli ◽  
Kaitlin Mugford ◽  
Stefanie Martina ◽  
Robert Brown ◽  
...  
Keyword(s):  
Movement Time ◽  
Prior Experience ◽  
Practical Significance ◽  
Escape Training ◽  
Specialized Training ◽  
Breathing Apparatus ◽  
Helicopter Landing ◽  
Total Movement ◽  
Sequence Performance ◽  
Total Movement Time

BACKGROUND: Emergency helicopter landing at sea is dangerous. Specialized training, known as helicopter underwater escape training (HUET), prepares occupants to quickly exit the helicopter, which often inverts and sinks. In most jurisdictions, helicopter occupants are equipped with a helicopter underwater egress breathing apparatus (HUEBA) to provide sufficient air for escape. HUET trainees report that the HUEBA is easy to use, but it is well known that learners are often overconfident in their judgement of learning. To better understand how the HUEBA affects HUET sequence performance, we investigated whether using the HUEBA influences the sequence movement time and number of errors.METHODS: Twelve participants (7 men and 5 women, mean age 25.33 9.57 SD) with no prior experience with HUET performed consecutive trials of the HUET sequence, 5 with the HUEBA and 5 without the HUEBA. Video of each trial recorded the total movement time and enabled movement time analyses of each component of the sequence: crossing arms, tucking the head, pushing the window, inserting the regulator, and releasing the seatbelt. These recordings were also used to score performance errors according to a checklist.RESULTS: Analyses revealed that using a HUEBA increased the total movement time and time to release the seatbelt by 0.36 and 0.39 s, respectively, in comparison to without the HUEBA.DISCUSSION: Our study illustrates that using the HUEBA during the HUET sequence increases total movement time and time to release the seatbelt. However, this difference is marginal and unlikely to have practical significance during underwater escape.King M, Sanli E, Mugford K, Martina S, Brown R, Carnahan H. Evaluation of the helicopter emergency breathing apparatus on egress performance. Aerosp Med Hum Perform. 2020; 91(12):962965.

Task-Specific Internal Models for Kinematic Transformations

2003 ◽  
Vol 90 (2) ◽  
pp. 578-585 ◽  
Author(s):  
Christine Tong ◽  
J. Randall Flanagan
Keyword(s):  
Internal Model ◽  
Dynamic Environment ◽  
Reaching Movements ◽  
Task Interference ◽  
Reaching Task ◽  
Visuomotor Transformations ◽  
Drawing Task ◽  
Kinematic Transformations ◽  
Memory Resources ◽  
Perceived Motion

Numerous studies of motor learning have focused on how people adapt their reaching movements to novel dynamic and visuomotor perturbations that alter the actual or visually perceived motion of the hand. An important finding from this work is that learning of novel dynamics generalizes across different movement tasks. Thus adaptation to an unusual force field generalizes from center-out reaching movements to circular movements ( Conditt et al. 1997 ). This suggests that subjects acquired an internal model of the dynamic environment that could be used to determine the motor commands needed for untrained movements. Using a task interference paradigm, we investigated whether transfer across tasks is also observed when learning visuomotor transformations. On day 1, all subjects adapted to a +30° rotation while making center-out-and-back reaching movements. After a delay of 5 min, different groups of subjects then adapted to a –30° rotation while performing either a continuous tracking task, a figure-eight drawing task, or the center-out-and-back reaching task. All subjects were then retested the next day on the +30° rotation in the reaching task. As expected, subjects who experienced the opposing rotations while performing the same reaching tasks showed no retention of learning for the first rotation when tested on day 2 ( Krakauer et al. 1999 ). In contrast, such retrograde interference was not observed in the two groups of subjects who experienced the opposing rotations while performing different tasks. In fact, their performance on day 2 was similar to that of control subjects who never experienced the opposite rotation. This lack of interference suggests that memory resources for visuomotor rotations are task specific.

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