Limits in motor control bandwidth during stick balancing

2013 ◽  
Vol 109 (10) ◽  
pp. 2523-2527 ◽  
Author(s):  
N. Peter Reeves ◽  
Pramod Pathak ◽  
John M. Popovich ◽  
Vilok Vijayanagar
Keyword(s):  
Motor Control ◽  
Natural Frequency ◽  
Muscle Activation ◽  
Threshold Effect ◽  
Trunk Muscles ◽  
Human Control ◽  
Agonist And Antagonist ◽  
The Central Nervous System ◽  
Human Motor ◽  
Electromyographic Signals

Why can we balance a yardstick but not a pencil on the tip of our finger? As with other physical systems, human motor control has constraints, referred to as bandwidth, which restricts the range of frequency over which the system can operate within some tolerated level of error. To investigate control bandwidth, the natural frequency of a stick used during a stick-balancing task was modified by adjusting the height of a mass attached to the stick. The ability to successfully balance the stick with the mass positioned at four different heights was determined. In addition, electromyographic signals from forearm and trunk muscles were recorded during the trials. We hypothesized that 1) the probability of successfully balancing would decrease as mass height decreased; and 2) the level of muscle activation in both agonist and antagonist would increase as the natural frequency of the stick increased. Results showed that as the mass height decreased the probability of successfully balancing the stick decreased. Changes in the probability of success with respect to mass height showed a threshold effect, suggesting that limits in human control bandwidth were approached at the lowest mass height. Also, the level of muscle activation in both the agonist and antagonist of the forearm and trunk increased linearly as the natural frequency of the stick increased. These changes in muscle activation suggest that the central nervous system adapts muscle activation to task dynamics, possibly to improve control bandwidth.

Control Mechanisms in Oscillatory Motor Behavior

2013 ◽  
Author(s):  
Davide Piovesan ◽  
Felix C. Huang
Keyword(s):  
Muscle Activation ◽  
Motor Behavior ◽  
Rhythmic Movement ◽  
Control Mechanisms ◽  
Rhythmic Movements ◽  
Movement Trajectories ◽  
Reduced Frequency ◽  
The Central Nervous System ◽  
Human Motor ◽  
Inertial Loading

Studies on unimpaired humans have demonstrated that the central nervous system employs internal representations of limb dynamics and intended movement trajectories for planning muscle activation during pointing and reaching tasks. However, when performing rhythmic movements, it has been hypothesized that a control scheme employing an autonomous oscillator — a simple feedback circuit lacking exogenous input — can maintain stable control. Here we investigate whether such simple control architectures that can realize rhythmic movement that we observe in experimental data. We asked subjects to perform rhythmic movements of the forearm while a robotic interface simulated inertial loading. Our protocol included unexpected increases in loading (catch trials) as a probe to reveal any systematic changes in frequency and amplitude. Our primary findings were that increased inertial loading resulted in reduced frequency of oscillations, and in some cases multiple frequencies. These results exhibit some agreement with an autonomous oscillator model, though other features are more consistent with feedforward planning of force. This investigation provides a theoretical and experimental framework to reveal basic computational elements for how the human motor system achieves skilled rhythmic movement.

Anticipatory postural mechanisms: Some evidence and methodological implications

1996 ◽  
Vol 19 (1) ◽  
pp. 77-78
Author(s):  
Tatsuya Kasai
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Motor Control ◽  
Postural Control ◽  
H Reflex ◽  
Human Motor Control ◽  
Therapeutic Implications ◽  
Anticipatory Postural Control ◽  
The Central Nervous System ◽  
Human Motor

AbstractTo understand the basic priorities of the central nervous system in human motor control, neurophysiological parameters are important. Certain H-reflex methods related to anticipatory postural control are particularly useful and may have therapeutic implications.

Segregation of agonist and antagonist systems minimizes the benefits of polarity

1997 ◽  
Vol 20 (2) ◽  
pp. 315-316
Author(s):  
William A. MacKay
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Motor Control ◽  
Lateral Inhibition ◽  
Explanatory Power ◽  
Physiological Mechanisms ◽  
Kinematic Theory ◽  
Agonist And Antagonist ◽  
The Central Nervous System

A purely kinematic theory of movement runs the risk of having no explanatory power because it neglects the internal generative structures of the central nervous system. Distributed interaction between the agonist and antagonist systems would better simulate physiological mechanisms of oscillation, lateral inhibition, and synchronization, all of which have important roles in motor control.

scholarly journals A Perspective on Muscle Synergies and Different Theories Related to Their Adaptation

Biomechanics ◽  
2021 ◽  
Vol 1 (2) ◽  
pp. 253-263
Author(s):  
Ashar Turky Abd ◽  
Rajat Emanuel Singh ◽  
Kamran Iqbal ◽  
Gannon White
Keyword(s):  
Sensory System ◽  
Principal Component ◽  
Building Blocks ◽  
Muscle Synergies ◽  
Clinical Settings ◽  
Decomposition Algorithms ◽  
Small Set ◽  
The Central Nervous System ◽  
Human Motor ◽  
Electromyographic Signals

The human motor system is a complex neuro-musculo sensory system that needs further investigations of neuro-muscular commands and sensory-motor coupling to decode movement execution. Some researchers suggest that the central nervous system (CNS) activates a small set of modules termed muscle synergies to simplify motor control. Further, these modules form functional building blocks of movement as they can explain the neurophysiological characteristics of movements. We can identify and extract these muscle synergies from electromyographic signals (EMG) recorded in the laboratory by using linear decomposition algorithms, such as principal component analysis (PCA) and non-Negative Matrix Factorization Algorithm (NNMF). For the past three decades, the hypothesis of muscle synergies has received considerable attention as we attempt to understand and apply the concept of muscle synergies in clinical settings and rehabilitation. In this article, we first explore the concept of muscle synergies. We then present different strategies of adaptation in these synergies that the CNS employs to accomplish a movement goal.

scholarly journals Changes in Muscle Strategies During Landing Task in Subjects With and Without Knee Genu Varum

2021 ◽  
Author(s):  
Mahboobeh Azizi ◽  
Khosrow Khademi ◽  
Mehri Ghasemi ◽  
Alireza Akbarzadegan
Keyword(s):  
Motor Control ◽  
Knee Joint ◽  
Lower Limb ◽  
Healthy Subjects ◽  
Muscle Activation ◽  
Control Strategies ◽  
Trunk Muscles ◽  
Genu Varum ◽  
Significant Difference ◽  
Offset Time

Introduction: Onset and offset activation of lower limb and trunk muscles may change the knee with genu varum during landing. These motor control strategies can be different from those in healthy subjects and contribute to more injuries in lower extremities. This study aimed to compare the delay time of the onset activity of the abdominal and lower limb muscles in the specific landing task. Materials and Methods: Ten females with genu varum deformity and ten females with normal knee participated in this case-control study. Genu varum deformity was measured by a camera capturing goniometer. The subjects were informed to land by preferred lower limb from a table (30 cm high) on a force plate. Vertical Ground Reaction Force (VGRF) was measured to clarify the onset of the landing task. Surface Electromyography (sEMG) of transverse abdominal/int. oblique (TA/IO), Vastus Medialis (VM), Vastus Lateralis (VL), Lateral Gastrocnemius (LG), and medial gastrocnemius (MG) muscles were recorded during landing. The difference between the onset activity of the above muscles and onset of VGRF was calculated as delay times and compared between muscles and between two groups. Also, the offset of activities and the intensity of muscle activation (normalized RMS) were compared between the two groups. Results: Lower limb and trunk muscles showed significantly different onset of activities in the genu varum group (P<0.05), whereas there was no significant difference in the onset of muscle activities in the healthy group. Results indicated significant differences between two groups in TA/IO, LG, and MG muscles and the genu varum group had longer delay time for motor control strategy (especially ankle strategy) in the landing task. Offset time of all muscles in the genu varum and healthy subjects had a significant difference between muscles, especially in gastrocnemius muscles (P<0.05). Also, there were significant changes between the two groups in LG and MG muscles (P<0.05). Normalized muscle activities (nRMS) generally indicated an increase in muscle activation of genu varum subjects (TA/IO, LG, MG) compared with the normal subjects (P<0.05). Conclusion: Motor control strategies in landing task is different in the genu varum group due to changes in biomechanics and properties of the knee joint. This variation may be due to changes in proprioception afferent pathways around the knee joint. An increase in muscle activation, delay, and offset time of muscle activities in these subjects, indicated that an increase in the degree of freedom may change motor control strategies. Internal anticipation and postural adjustment of the landing task in these subjects need more motor unit recruitment (an increase in nRMS). This deformity in the knee joint might affect some activities and possibly cause knee changes such as osteoarthritis.

scholarly journals A Human-like Upper-limb Motion Planner: Generating naturalistic movements for humanoid robots

2021 ◽  
Vol 18 (2) ◽  
pp. 172988142199858
Author(s):  
Gianpaolo Gulletta ◽  
Eliana Costa e Silva ◽  
Wolfram Erlhagen ◽  
Ruud Meulenbroek ◽  
Maria Fernanda Pires Costa ◽  
...  
Keyword(s):  
Motor Control ◽  
Upper Limb ◽  
Planning Process ◽  
Computational Cost ◽  
Humanoid Robots ◽  
Efficient Manner ◽  
Daily Lives ◽  
Human Motor Control ◽  
Planning Algorithm ◽  
Human Motor

As robots are starting to become part of our daily lives, they must be able to cooperate in a natural and efficient manner with humans to be socially accepted. Human-like morphology and motion are often considered key features for intuitive human–robot interactions because they allow human peers to easily predict the final intention of a robotic movement. Here, we present a novel motion planning algorithm, the Human-like Upper-limb Motion Planner, for the upper limb of anthropomorphic robots, that generates collision-free trajectories with human-like characteristics. Mainly inspired from established theories of human motor control, the planning process takes into account a task-dependent hierarchy of spatial and postural constraints modelled as cost functions. For experimental validation, we generate arm-hand trajectories in a series of tasks including simple point-to-point reaching movements and sequential object-manipulation paradigms. Being a major contribution to the current literature, specific focus is on the kinematics of naturalistic arm movements during the avoidance of obstacles. To evaluate human-likeness, we observe kinematic regularities and adopt smoothness measures that are applied in human motor control studies to distinguish between well-coordinated and impaired movements. The results of this study show that the proposed algorithm is capable of planning arm-hand movements with human-like kinematic features at a computational cost that allows fluent and efficient human–robot interactions.

scholarly journals The Effects of Abdominal Hypopressive Training on Postural Control and Deep Trunk Muscle Activation: A Randomized Controlled Trial

2021 ◽  
Vol 18 (5) ◽  
pp. 2741
Author(s):  
María del Mar Moreno-Muñoz ◽  
Fidel Hita-Contreras ◽  
María Dolores Estudillo-Martínez ◽  
Agustín Aibar-Almazán ◽  
Yolanda Castellote-Caballero ◽  
...  
Keyword(s):  
Postural Control ◽  
Muscle Activation ◽  
Center Of Pressure ◽  
Controlled Trial ◽  
Trunk Muscle ◽  
Posture Control ◽  
Trunk Muscles ◽  
Control Group ◽  
Female Population ◽  
Imaging Results

Background: Abdominal Hypopressive Training (AHT) provides postural improvement, and enhances deep trunk muscle activation. However, until recently, there was a lack of scientific literature supporting these statements. The major purpose of this study was to investigate the effect of AHT on posture control and deep trunk muscle function. Methods: 125 female participants aged 18–60 were randomly allocated to the Experimental Group (EG), consisting of two sessions of 30 min per week for 8 weeks of AHT, or the Control Group (CG), who did not receive any treatment. Postural control was measured with a stabilometric platform to assess the static balance and the activation of deep trunk muscles (specifically the Transverse Abdominal muscle (TrA)), which was measured by real-time ultrasound imaging. Results: The groups were homogeneous at baseline. Statistical differences were identified between both groups after intervention in the Surface of the Center of Pressure (CoP) Open-Eyes (S-OE) (p = 0.001, Cohen’s d = 0.60) and the Velocity of CoP under both conditions; Open-Eyes (V-OE) (p = 0.001, Cohen´s d = 0.63) and Close-Eyes (V-CE) (p = 0.016, Cohen´s d = 0.016), with the EG achieving substantial improvements. Likewise, there were statistically significant differences between measurements over time for the EG on S-OE (p < 0.001, Cohen´s d = 0.99); V-OE (p = 0.038, Cohen´s d = 0.27); V-CE (p = 0.006, Cohen´s d = 0.39), anteroposterior movements of CoP with Open-Eyes (RMSY-OE) (p = 0.038, Cohen´s d = 0.60) and activity of TrA under contraction conditions (p < 0.001, Cohen´s d = 0.53). Conclusions: The application of eight weeks of AHT leads to positive outcomes in posture control, as well as an improvement in the deep trunk muscle contraction in the female population.

Sign in / Sign up

Export Citation Format

Share Document