scholarly journals Promoting Motor Variability During Robotic Assistance Enhances Motor Learning of Dynamic Tasks

2021 ◽  
Vol 14 ◽  
Author(s):  
Özhan Özen ◽  
Karin A. Buetler ◽  
Laura Marchal-Crespo
Keyword(s):  
Motor Learning ◽  
Sense Of Agency ◽  
Control Group ◽  
Haptic Guidance ◽  
Movement Variability ◽  
Robotic Training ◽  
Motor Variability ◽  
End Effector ◽  
Dynamic Task ◽  
Somatosensory Information

Despite recent advances in robot-assisted training, the benefits of haptic guidance on motor (re)learning are still limited. While haptic guidance may increase task performance during training, it may also decrease participants' effort and interfere with the perception of the environment dynamics, hindering somatosensory information crucial for motor learning. Importantly, haptic guidance limits motor variability, a factor considered essential for learning. We propose that Model Predictive Controllers (MPC) might be good alternatives to haptic guidance since they minimize the assisting forces and promote motor variability during training. We conducted a study with 40 healthy participants to investigate the effectiveness of MPCs on learning a dynamic task. The task consisted of swinging a virtual pendulum to hit incoming targets with the pendulum ball. The environment was haptically rendered using a Delta robot. We designed two MPCs: the first MPC—end-effector MPC—applied the optimal assisting forces on the end-effector. A second MPC—ball MPC—applied its forces on the virtual pendulum ball to further reduce the assisting forces. The participants' performance during training and learning at short- and long-term retention tests were compared to a control group who trained without assistance, and a group that trained with conventional haptic guidance. We hypothesized that the end-effector MPC would promote motor variability and minimize the assisting forces during training, and thus, promote learning. Moreover, we hypothesized that the ball MPC would enhance the performance and motivation during training but limit the motor variability and sense of agency (i.e., the feeling of having control over their movements), and therefore, limit learning. We found that the MPCs reduce the assisting forces compared to haptic guidance. Training with the end-effector MPC increases the movement variability and does not hinder the pendulum swing variability during training, ultimately enhancing the learning of the task dynamics compared to the other groups. Finally, we observed that increases in the sense of agency seemed to be associated with learning when training with the end-effector MPC. In conclusion, training with MPCs enhances motor learning of tasks with complex dynamics and are promising strategies to improve robotic training outcomes in neurological patients.

scholarly journals High variability impairs motor learning regardless of whether it affects task performance

2018 ◽  
Vol 119 (1) ◽  
pp. 39-48 ◽  
Author(s):  
Marco Cardis ◽  
Maura Casadio ◽  
Rajiv Ranganathan
Keyword(s):  
Motor Learning ◽  
Task Performance ◽  
Null Space ◽  
Motor Task ◽  
Task Space ◽  
Movement Variability ◽  
Motor Variability ◽  
Different Dimensions ◽  
Left And Right

Motor variability plays an important role in motor learning, although the exact mechanisms of how variability affects learning are not well understood. Recent evidence suggests that motor variability may have different effects on learning in redundant tasks, depending on whether it is present in the task space (where it affects task performance) or in the null space (where it has no effect on task performance). We examined the effect of directly introducing null and task space variability using a manipulandum during the learning of a motor task. Participants learned a bimanual shuffleboard task for 2 days, where their goal was to slide a virtual puck as close as possible toward a target. Critically, the distance traveled by the puck was determined by the sum of the left- and right-hand velocities, which meant that there was redundancy in the task. Participants were divided into five groups, based on both the dimension in which the variability was introduced and the amount of variability that was introduced during training. Results showed that although all groups were able to reduce error with practice, learning was affected more by the amount of variability introduced rather than the dimension in which variability was introduced. Specifically, groups with higher movement variability during practice showed larger errors at the end of practice compared with groups that had low variability during learning. These results suggest that although introducing variability can increase exploration of new solutions, this may adversely affect the ability to retain the learned solution.NEW & NOTEWORTHY We examined the role of introducing variability during motor learning in a redundant task. The presence of redundancy allows variability to be introduced in different dimensions: the task space (where it affects task performance) or the null space (where it does not affect task performance). We found that introducing variability affected learning adversely, but the amount of variability was more critical than the dimension in which variability was introduced.

scholarly journals High variability impairs motor learning regardless of whether it affects task performance

2017 ◽  
Author(s):  
Marco Cardis ◽  
Maura Casadio ◽  
Rajiv Ranganathan
Keyword(s):  
Motor Learning ◽  
Task Performance ◽  
Null Space ◽  
Motor Task ◽  
High Variability ◽  
Task Space ◽  
Movement Variability ◽  
Motor Variability ◽  
Left And Right ◽  
And Task

AbstractMotor variability plays an important role in motor learning, although the exact mechanisms of how variability affects learning is not well understood. Recent evidence suggests that motor variability may have different effects on learning in redundant tasks, depending on whether it is present in the task space (where it affects task performance), or in the null space (where it has no effect on task performance). Here we examined the effect of directly introducing null and task space variability using a manipulandum during the learning of a motor task. Participants learned a bimanual shuffleboard task for 2 days, where their goal was to slide a virtual puck as close as possible towards a target. Critically, the distance traveled by the puck was determined by the sum of the left and right hand velocities, which meant that there was redundancy in the task. Participants were divided into five groups – based on both the dimension in which the variability was introduced and the amount of variability that was introduced during training. Results showed that although all groups were able to reduce error with practice, learning was affected more by the amount of variability introduced rather than the dimension in which variability was introduced. Specifically, groups with higher movement variability during practice showed larger errors at the end of practice compared to groups that had low variability during learning. These results suggest that although introducing variability can increase exploration of new solutions, this may come at a cost of decreased stability of the learned solution.

scholarly journals Somatosensory signals from the controllers of an extra robotic finger support motor learning

2021 ◽  
Author(s):  
Elena Amoruso ◽  
Lucy Dowdall ◽  
Mathew Thomas Kollamkulam ◽  
Obioha Ukaegbu ◽  
Paulina Kieliba ◽  
...  
Keyword(s):  
Motor Control ◽  
Motor Learning ◽  
Pressure Sensors ◽  
Motor Task ◽  
Body Part ◽  
Control Group ◽  
Body Parts ◽  
Position Information ◽  
Somatosensory Information ◽  
Alternative Means

Considerable resources are being invested to provide bidirectional control of substitutive and augmentative motor interfaces through artificial somatosensory feedback. Here, we investigated whether intrinsic somatosensory information, from body part(s) proportionally controlling an augmentation device, can be utilised to infer the device state and position, to better support motor control and learning. In a placebo-controlled design, we used local anaesthetic to attenuate somatosensory inputs to the big toes while participants learned to operate a toe-controlled robotic extra finger (Third Thumb) using pressure sensors. Motor learning outcomes were compared against a control group who received sham anaesthetic. The availability of somatosensory cues about the amount of exerted pressure generally facilitated acquisition, retention and transfer of motor skills, and performance under cognitive load. Motor performance was not impaired by anaesthesia when tasks involved close collaboration with the biological fingers, indicating that the brain could close the gap of the missing pressure signals by alternative means, including feedback from other body parts involved in the motor task. Together, our findings demonstrate that there are intrinsic natural avenues to provide surrogate position information to support motor control of an artificial body part, beyond artificial extrinsic signalling.

scholarly journals Multidirectional Overground Robotic Training Leads to Improvements in Balance in Older Adults

Robotics ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 101
Author(s):  
Lara A. Thompson ◽  
Mehdi Badache ◽  
Joao Augusto Renno Brusamolin ◽  
Marzieh Savadkoohi ◽  
Jelani Guise ◽  
...  
Keyword(s):  
Older Adults ◽  
Healthy Aging ◽  
Robotic System ◽  
Control Group ◽  
Support Surface ◽  
Training Methods ◽  
Robotic Training ◽  
Balance Confidence ◽  
Balance Ability ◽  
Abc Scale

For the rapidly growing aging demographic worldwide, robotic training methods could be impactful towards improving balance critical for everyday life. Here, we investigated the hypothesis that non-bodyweight supportive (nBWS) overground robotic balance training would lead to improvements in balance performance and balance confidence in older adults. Sixteen healthy older participants (69.7 ± 6.7 years old) were trained while donning a harness from a distinctive NaviGAITor robotic system. A control group of 11 healthy participants (68.7 ± 5.0 years old) underwent the same training but without the robotic system. Training included 6 weeks of standing and walking tasks while modifying: (1) sensory information (i.e., with and without vision (eyes-open/closed), with more and fewer support surface cues (hard or foam surfaces)) and (2) base-of-support (wide, tandem and single-leg standing exercises). Prior to and post-training, balance ability and balance confidence were assessed via the balance error scoring system (BESS) and the Activities specific Balance Confidence (ABC) scale, respectively. Encouragingly, results showed that balance ability improved (i.e., BESS errors significantly decreased), particularly in the nBWS group, across nearly all test conditions. This result serves as an indication that robotic training has an impact on improving balance for healthy aging individuals.

scholarly journals Motor learning-based activities may improve functional ability in adults with severe cerebral palsy: A controlled pilot study

2021 ◽  
pp. 1-11
Author(s):  
Helle Hüche Larsen ◽  
Rasmus Feld Frisk ◽  
Maria Willerslev-Olsen ◽  
Jens Bo Nielsen
Keyword(s):  
Cerebral Palsy ◽  
Motor Learning ◽  
Motor Function ◽  
Functional Ability ◽  
Active Group ◽  
Control Group ◽  
Gross Motor ◽  
Gross Motor Function ◽  
Learning Principles

BACKGROUND: Cerebral palsy (CP) is a neurodevelopmental disturbance characterized by impaired control of movement. Function often decreases and 15% of adults are classified as severely affected (Gross Motor Function Classification Scale III-V). Little is known about interventions that aim to improve functional abilities in this population. OBJECTIVE: To evaluate a 12-week intervention based on motor learning principles on functional ability in adults with severe CP. METHODS: 16 adults (36±10 years, GMFCS III-V) were enrolled and divided into an intervention group (Active group) and a standard care group (Control group). Primary outcome measure was Gross Motor Function Measure (GMFM-88). Secondary measures were neurological status. The Active group were measured at baseline, after the intervention and at one-month follow-up. The Control group were measured at baseline and after one month. RESULTS: Analysis showed statistically significant improvement in GMFM-88 for the Active group from baseline to post assessment compared with the Control group (group difference: 5 points, SE 14.5, p = 0.008, CI: 1.2 to 8.7). Improvements were maintained at follow-up. Results from the neurological screening showed no clear tendencies. CONCLUSIONS: The study provides support that activities based on motor learning principles may improve gross motor function in adults with severe CP.

scholarly journals Optimization of Dynamic Task Location within a Manipulator’s Workspace for the Utilization of the Minimum Required Joint Torques

Electronics ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 288
Author(s):  
Adam Wolniakowski ◽  
Charalampos Valsamos ◽  
Kanstantsin Miatliuk ◽  
Vassilis Moulianitis ◽  
Nikos Aspragathos
Keyword(s):  
High Performance ◽  
Human Robot Interaction ◽  
Optimal Position ◽  
End Effector ◽  
Joint Torques ◽  
Dynamic Task ◽  
Arbitrary Position ◽  
Simulation Results ◽  
Set Up ◽  
Task Placement

The determination of the optimal position of a robotic task within a manipulator’s workspace is crucial for the manipulator to achieve high performance regarding selected aspects of its operation. In this paper, a method for determining the optimal task placement for a serial manipulator is presented, so that the required joint torques are minimized. The task considered comprises the exercise of a given force in a given direction along a 3D path followed by the end effector. Given that many such tasks are usually conducted by human workers and as such the utilized trajectories are quite complex to model, a Human Robot Interaction (HRI) approach was chosen to define the task, where the robot is taught the task trajectory by a human operator. Furthermore, the presented method considers the singular free paths of the manipulator’s end-effector motion in the configuration space. Simulation results are utilized to set up a physical execution of the task in the optimal derived position within a UR-3 manipulator’s workspace. For reference the task is also placed at an arbitrary “bad” location in order to validate the simulation results. Experimental results verify that the positioning of the task at the optimal location derived by the presented method allows for the task execution with minimum joint torques as opposed to the arbitrary position.

scholarly journals Explicit motor sequence learning after stroke: a neuropsychological study

2021 ◽  
Author(s):  
Cristina Russo ◽  
Laura Veronelli ◽  
Carlotta Casati ◽  
Alessia Monti ◽  
Laura Perucca ◽  
...  
Keyword(s):  
Basal Ganglia ◽  
Motor Learning ◽  
Upper Limb ◽  
Motor Recovery ◽  
Finger Tapping ◽  
Control Group ◽  
Stroke Severity ◽  
Motor Sequence ◽  
Stroke Patients ◽  
Motor Practice

AbstractMotor learning interacts with and shapes experience-dependent cerebral plasticity. In stroke patients with paresis of the upper limb, motor recovery was proposed to reflect a process of re-learning the lost/impaired skill, which interacts with rehabilitation. However, to what extent stroke patients with hemiparesis may retain the ability of learning with their affected limb remains an unsolved issue, that was addressed by this study. Nineteen patients, with a cerebrovascular lesion affecting the right or the left hemisphere, underwent an explicit motor learning task (finger tapping task, FTT), which was performed with the paretic hand. Eighteen age-matched healthy participants served as controls. Motor performance was assessed during the learning phase (i.e., online learning), as well as immediately at the end of practice, and after 90 min and 24 h (i.e., retention). Results show that overall, as compared to the control group, stroke patients, regardless of the side (left/right) of the hemispheric lesion, do not show a reliable practice-dependent improvement; consequently, no retention could be detected in the long-term (after 90 min and 24 h). The motor learning impairment was associated with subcortical damage, predominantly affecting the basal ganglia; conversely, it was not associated with age, time elapsed from stroke, severity of upper-limb motor and sensory deficits, and the general neurological condition. This evidence expands our understanding regarding the potential of post-stroke motor recovery through motor practice, suggesting a potential key role of basal ganglia, not only in implicit motor learning as previously pointed out, but also in explicit finger tapping motor tasks.

scholarly journals Motor Sequences - Separating The Sequence From The Motor. A longitudinal rsfMRI Study

2021 ◽  
Author(s):  
ATP Jäger ◽  
JM Huntenburg ◽  
SA Tremblay ◽  
U Schneider ◽  
S Grahl ◽  
...  
Keyword(s):  
Functional Connectivity ◽  
Motor Learning ◽  
Resting State ◽  
Primary Motor Cortex ◽  
Control Group ◽  
Motor Execution ◽  
Motor Sequence ◽  
Resting State Functional Connectivity ◽  
Fast Learning ◽  
Slow Learning

AbstractIn motor learning, sequence-specificity, i.e. the learning of specific sequential associations, has predominantly been studied using task-based fMRI paradigms. However, offline changes in resting state functional connectivity after sequence-specific motor learning are less well understood. Previous research has established that plastic changes following motor learning can be divided into stages including fast learning, slow learning and retention. A description of how resting state functional connectivity after sequence-specific motor sequence learning (MSL) develops across these stages is missing. This study aimed to identify plastic alterations in whole-brain functional connectivity after learning a complex motor sequence by contrasting an active group who learned a complex sequence with a control group who performed a control task matched for motor execution. Resting state fMRI and behavioural performance were collected in both groups over the course of 5 consecutive training days and at follow-up after 12 days to encompass fast learning, slow learning, overall learning and retention. Between-group interaction analyses showed sequence-specific increases in functional connectivity during fast learning in the sensorimotor territory of the internal segment of right globus pallidus (GPi), and sequence-specific decreases in right supplementary motor area (SMA) in overall learning. We found that connectivity changes in key regions of the motor network including the superior parietal cortex (SPC) and primary motor cortex (M1) were not a result of sequence-specific learning but were instead linked to motor execution. Our study confirms the sequence-specific role of SMA and GPi that has previously been identified in online task-based learning studies in humans and primates, and extends it to resting state network changes after sequence-specific MSL. Finally, our results shed light on a timing-specific plasticity mechanism between GPi and SMA following MSL.

scholarly journals The Effect of External Attentional Focus and Self-Controlled Feedback on Motor Learning in Older Adults

2020 ◽  
Vol 27 (1) ◽  
pp. 9-13
Author(s):  
Sima Razaghi ◽  
Esmaeel Saemi ◽  
Rasool Abedanzadeh
Keyword(s):  
Older Adults ◽  
Motor Learning ◽  
Retention Test ◽  
Attentional Focus ◽  
Focus Of Attention ◽  
The Other ◽  
Acquisition Phase ◽  
Control Group ◽  
External Focus ◽  
Mixed Anova

AbstractIntroduction. External focus instruction and self-controlled feedback have beneficial effects on motor learning. The purpose of the present study was to investigate the benefits of combined effects of external focus instruction and self-controlled feedback on balance performance in older adults.Material and Methods. Forty older adults (mean age: 63.21 ± 3.6 years; all female) were selected and randomly divided into 4 groups: self-controlled feedback, external attention, external attention/self-controlled feedback and control group. The task of standing on the platform of the stabilometer device and trying to keep the platform horizontally as much as possible was performed in each 30-sec. trial. The participants of self-controlled group received feedback on the timing of balance after the trials. In the external focus of attention, participants noticed the signs that were located horizontally ahead of their feet. The test was conducted in two sessions. In the acquisition phase, 10 trials of 30 seconds were performed and the retention test was completed 24 hours later as 5 trials of 30 seconds.Results. The results of mixed ANOVA on time data as an indicator of balance in the acquisition phase showed that the mixed group of external focus of attention and self-controlled feedback had better performance than the other groups (p = 0.004). In the retention test, the results of mixed ANOVA showed that the participants in the combined group of external focus and self-controlled feedback had better performance than the other groups (p = 0.006). The external focus of attention and self-controlled feedback performed similarly, and both were superior to the control group (p < 0.05).Conclusions. The results of this study, supporting the OPTIMAL theory of motor learning in the elderly, showed that the combination of two factors of external focus and self-controlled feedback has a double advantage over the presence of each of the factors. Therefore, it is suggested that the combinations of external focus instructions and self-controlled feedback should be used to improve performance and motor learning in the classes of practical and clinical rehabilitation fields.

scholarly journals Concurrent Validity of Physiological Cost Index in Walking over Ground and during Robotic Training in Subacute Stroke Patients

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Anna Sofia Delussu ◽  
Giovanni Morone ◽  
Marco Iosa ◽  
Maura Bragoni ◽  
Stefano Paolucci ◽  
...  
Keyword(s):  
Random Sequence ◽  
Pearson Correlation ◽  
Control Group ◽  
Stroke Patients ◽  
Robotic Training ◽  
Cost Index ◽  
Physiological Cost ◽  
Subacute Stroke ◽  
Weight Support ◽  
Walking Tests

Physiological Cost Index (PCI) has been proposed to assess gait demand. The purpose of the study was to establish whether PCI is a valid indicator in subacute stroke patients of energy cost of walking in different walking conditions, that is, over ground and on the Gait Trainer (GT) with body weight support (BWS). The study tested if correlations exist between PCI and ECW, indicating validity of the measure and, by implication, validity of PCI. Six patients (patient group (PG)) with subacute stroke and 6 healthy age- and size-matched subjects as control group (CG) performed, in a random sequence in different days, walking tests overground and on the GT with 0, 30, and 50% BWS. There was a good to excellent correlation between PCI and ECW in the observed walking conditions: in PG Pearson correlation was 0.919 (p<0.001); in CG Pearson correlation was 0.852 (p<0.001). In conclusion, the high significant correlations between PCI and ECW, in all the observed walking conditions, suggest that PCI is a valid outcome measure in subacute stroke patients.

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