Motor Control
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2021 ◽  
Author(s):  
Rune Berg ◽  
Henrik Lindén ◽  
Peter Petersen ◽  
Mikkel Vestergaard

Abstract Although the nervous system is elegantly orchestrating movements, the underlying neural principles remain unclear. Since flexor- and extensor-muscles alternate during movements like walking, it is often assumed that the responsible neural circuitry is similarly alternating in opposition. Here, we present ensemble recordings of neurons in the lumbar spinal cord that indicate that, rather than alternation, the population is performing a "rotation" in neural space, i.e. the neural activity is cycling through all phases continuously during the rhythmic behavior. The radius of rotation correlates with the intended muscle force. Since existing models of spinal motor control offer an inadequate explanation of rotation, we propose a new theory of neural generation of movement from which this and other unresolved issues, such as speed regulation, force control, and multi-functionalism, are conveniently explained.


PLoS ONE ◽  
2021 ◽  
Vol 16 (10) ◽  
pp. e0258747
Author(s):  
Abigail R. Bradshaw ◽  
Carolyn McGettigan

Joint speech behaviours where speakers produce speech in unison are found in a variety of everyday settings, and have clinical relevance as a temporary fluency-enhancing technique for people who stutter. It is currently unknown whether such synchronisation of speech timing among two speakers is also accompanied by alignment in their vocal characteristics, for example in acoustic measures such as pitch. The current study investigated this by testing whether convergence in voice fundamental frequency (F0) between speakers could be demonstrated during synchronous speech. Sixty participants across two online experiments were audio recorded whilst reading a series of sentences, first on their own, and then in synchrony with another speaker (the accompanist) in a number of between-subject conditions. Experiment 1 demonstrated significant convergence in participants’ F0 to a pre-recorded accompanist voice, in the form of both upward (high F0 accompanist condition) and downward (low and extra-low F0 accompanist conditions) changes in F0. Experiment 2 demonstrated that such convergence was not seen during a visual synchronous speech condition, in which participants spoke in synchrony with silent video recordings of the accompanist. An audiovisual condition in which participants were able to both see and hear the accompanist in pre-recorded videos did not result in greater convergence in F0 compared to synchronisation with the pre-recorded voice alone. These findings suggest the need for models of speech motor control to incorporate interactions between self- and other-speech feedback during speech production, and suggest a novel hypothesis for the mechanisms underlying the fluency-enhancing effects of synchronous speech in people who stutter.


2021 ◽  
Vol 15 ◽  
Author(s):  
Tjasa Kunavar ◽  
Marko Jamšek ◽  
Marie Barbiero ◽  
Gunnar Blohm ◽  
Daichi Nozaki ◽  
...  

Our sensorimotor control is well adapted to normogravity environment encountered on Earth and any change in gravity significantly disturbs our movement. In order to produce appropriate motor commands for aimed arm movements such as pointing or reaching, environmental changes have to be taken into account. This adaptation is crucial when performing successful movements during microgravity and hypergravity conditions. To mitigate the effects of changing gravitational levels, such as the changed movement duration and decreased accuracy, we explored the possible beneficial effects of gravity compensation on movement. Local gravity compensation was achieved using a motorized robotic device capable of applying precise forces to the subject’s wrist that generated a normogravity equivalent torque at the shoulder joint during periods of microgravity and hypergravity. The efficiency of the local gravity compensation was assessed with an experiment in which participants performed a series of pointing movements toward the target on a screen during a parabolic flight. We compared movement duration, accuracy, movement trajectory, and muscle activations of movements during periods of microgravity and hypergravity with conditions when local gravity compensation was provided. The use of local gravity compensation at the arm mitigated the changes in movement duration, accuracy, and muscle activity. Our results suggest that the use of such an assistive device helps with movements during unfamiliar environmental gravity.


2021 ◽  
Vol 15 ◽  
Author(s):  
Saugat Bhattacharyya ◽  
Amit Konar ◽  
Haider Raza ◽  
Anwesha Khasnobish

2021 ◽  
Vol 12 (4) ◽  
pp. 195
Author(s):  
Mengyuan Dong ◽  
Yuezhen Fan ◽  
Donglei Yu ◽  
Qingchun Wang

Vehicle driving safety is an important performance indicator for vehicles, and there is still much room for development in the active safety control of electric vehicles. A vehicle rollover is an important road traffic safety problem, as rollover accidents cause serious casualties and huge economic losses. It is very easy for vehicles in high-speed sharp turns or high-speed overtaking to roll over; in order to improve the vehicle in these conditions with the anti-rollover stability, this study proposed a real-time motor control strategy, mainly through the acquisition of vehicle attitude data and the use of multi-sensor fusion on the vehicle running state for real time. The lateral load transfer rate was used as the vehicle rollover evaluation index, and the test results indicate that when the real-time rollover index exceeds the set limit safety threshold, the motor speed is reduced through active control so that the vehicle avoids rollover accidents, or the risk of rollover is reduced. The STM32F103RET6 was used as the main chip for hardware design, control board fabrication, control program software design, and joint testing of software and hardware. The tests and data analysis prove that the motor control strategy is reliable in real time and can significantly improve the active safety of electric vehicles.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ronit Feingold-Polak ◽  
Anna Yelkin ◽  
Shmil Edelman ◽  
Amir Shapiro ◽  
Shelly Levy-Tzedek

AbstractImpairment in force regulation and motor control impedes the independence of individuals with stroke by limiting their ability to perform daily activities. There is, at present, incomplete information about how individuals with stroke regulate the application of force and control their movement when reaching, grasping, and lifting objects of different weights, located at different heights. In this study, we assess force regulation and kinematics when reaching, grasping, and lifting a cup of two different weights (empty and full), located at three different heights, in a total of 46 participants: 30 sub-acute stroke participants, and 16 healthy individuals. We found that the height of the reached target affects both force calibration and kinematics, while its weight affects only the force calibration when post-stroke and healthy individuals perform a reach-to-grasp task. There was no difference between the two groups in the mean and peak force values. The individuals with stroke had slower, jerkier, less efficient, and more variable movements compared to the control group. This difference was more pronounced with increasing stroke severity. With increasing stroke severity, post-stroke individuals demonstrated altered anticipation and preparation for lifting, which was evident for either cortical lesion side.


Author(s):  
Jaejin Lee ◽  
Dohyun Kim ◽  
Yoonkyum Shin ◽  
Chunghwi Yi ◽  
Hyeseon Jeon ◽  
...  

BACKGROUND: To restore core stability, abdominal drawing-in maneuver (ADIM), abdominal bracing (AB), and dynamic neuromuscular stabilization (DNS) have been employed but outcome measures varied and one intervention was not superior over another. OBJECTIVE: The purpose of this study was to compare the differential effects of ADIM, AB, and DNS on diaphragm movement, abdominal muscle thickness difference, and external abdominal oblique (EO) electromyography (EMG) amplitude. METHODS: Forty-one participants with core instability participated in this study. The subjects performed ADIM, AB, and DNS in random order. A Simi Aktisys and Pressure Biofeedback Unit (PBU) were utilized to measure core stability, an ultrasound was utilized to measure diaphragm movement and measure abdominal muscles thickness and EMG was utilized to measure EO amplitude. Analysis of variance (ANOVA) was conducted at P< 0.05. RESULTS: Diaphragm descending movement and transverse abdominis (TrA) and internal abdominal oblique (IO) thickness differences were significantly increased in DNS compared to ADIM and AB (P< 0.05). EO amplitude was significantly increased in AB compared to ADIM, and DNS. CONCLUSIONS: DNS was the best technique to provide balanced co-activation of the diaphragm and TrA with relatively less contraction of EO and subsequently producing motor control for efficient core stabilization.


2021 ◽  
Vol 3 ◽  
Author(s):  
Arata Kimura ◽  
Toshiharu Yokozawa ◽  
Hiroki Ozaki

Coordination is a multidisciplinary concept in human movement science, particularly in the field of biomechanics and motor control. However, the term is not used synonymously by researchers and has substantially different meanings depending on the studies. Therefore, it is necessary to clarify the meaning of coordination to avoid confusion. The meaning of coordination in motor control from computational and ecological perspectives has been clarified, and the meanings differed between them. However, in biomechanics, each study has defined the meaning of the term and the meanings are diverse, and no study has attempted to bring together the diversity of the meanings of the term. Therefore, the purpose of this study is to provide a summary of the different meanings of coordination across the theoretical landscape and clarify the meaning of coordination in biomechanics. We showed that in biomechanics, coordination generally means the relation between elements that act toward the achievement of a motor task, which we call biomechanical coordination. We also showed that the term coordination used in computational and ecological perspectives has two different meanings, respectively. Each one had some similarities with biomechanical coordination. The findings of this study lead to an accurate understanding of the concept of coordination, which would help researchers formulate their empirical arguments for coordination in a more transparent manner. It would allow for accurate interpretation of data and theory development. By comprehensively providing multiple perspectives on coordination, this study intends to promote coordination studies in biomechanics.


Author(s):  
Mevhibe Saricaoglu ◽  
Lutfu Hanoglu ◽  
Guven Toprak ◽  
Nesrin Helvaci Yilmaz ◽  
Burak Yulug

Introduction: The pre-supplementary motor area (Pre-SMA) plays a pivotal role in the control of voluntary motor control and freezing of gait (FOG) pathophysiological mechanism. Here, we aimed to modulate if the pre-SMA would have beneficial effects on motor and behavioural outcomes in freezing of gait. To test this hypothesis, we examined the left pre-SMA stimulating effect of repetitive Transcranial Magnetic Stimulation (rTMS) on motor, cognitive and behavioural parameters in Parkinson’s patients with FOG. Method: The study included 20 Parkinson’s patients with FOG (3 females, 17 males) who received the left Pre-SMA rTMS procedure. The clinical assessments were performed on all patients at the baseline and the patients were re-evaluated under the same clinical conditions one week after the end of the sessions. Results & Discussion: We found significant improvements in motor, cognitive and behavioural symptoms (p<0.05). The main finding of our study is that Pre-SMA is an attractive stimulation area leading to critical improvement of symptoms of Parkinson' s patients with FOG. Conclusion: The high-frequency rTMS stimulation over the left preSMA has a restorative effect on the motor, cognitive and behavioural symptoms of Parkinson' s patients with FOG.


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