Could Different Directions of Infant Stepping Be Controlled by the Same Locomotor Central Pattern Generator?

2000 ◽  
Vol 83 (5) ◽  
pp. 2814-2824 ◽  
Author(s):  
Tania Lamb ◽  
Jaynie F. Yang
Keyword(s):  
Central Pattern Generator ◽  
Muscle Activation ◽  
Pattern Generator ◽  
Swing Phase ◽  
Smooth Transition ◽  
Cycle Duration ◽  
Human Infants ◽  
Activation Patterns ◽  
Muscle Activation Patterns ◽  
The Relationship

This study examined the idea of whether the same central pattern generator (CPG) for locomotion can control different directions of walking in humans. Fifty-two infants, aged 2–11 mo, were tested. Infants were supported to walk on a treadmill at a variety of speeds. If forward stepping was elicited, stepping in the other directions (primarily sideways and backward) was attempted. The orientation of the infant on the treadmill belt determined the direction of stepping. In some infants, we also attempted to obtain a smooth transition from one direction to another by gradually changing the orientation of the infant during a stepping sequence. Limb segment motion and surface electromyography from the muscles of the lower limb were recorded. Most infants who showed sustained forward walking also could walk in all other directions. Thirty-three of 34 infants tested could step sideways. The success of eliciting backward stepping was 69%. Most of the infants who did not meet our backward stepping criteria did, however, make stepping movements. The different directions of stepping had similar responses to changes in treadmill speed. The relationship between stance and swing phase durations and cycle duration were the same regardless of the direction of stepping across a range of speeds. Some differences were noted in the muscle activation patterns during different directions of walking. For example, the hamstrings were much more active during the swing phase of backward walking compared with forward walking. The quadriceps was more active in the trailing leg during sideways walking. In some infants, we were able to elicit stepping along a continuum of directions. We found no discrete differences in either the electromyographic patterns or the temporal parameters of stepping as the direction of stepping was gradually changed. The results support the idea that the same locomotor CPG controls different directions of stepping in human infants. The fact that most infants were able to step in all directions, the similarity in the response to speed changes, and the absence of any discrete changes as the direction of stepping was changed gradually are all consistent with this hypothesis.

How the Brain Generates Movement

2012 ◽  
Vol 24 (2) ◽  
pp. 289-331 ◽  
Author(s):  
Uri Rokni ◽  
Haim Sompolinsky
Keyword(s):  
Muscle Activation ◽  
Pattern Generator ◽  
General Purpose ◽  
Neural Oscillator ◽  
Central Component ◽  
Activation Patterns ◽  
Muscle Activation Patterns ◽  
Movement Segment ◽  
The Brain ◽  
Basic Movement

In this study, we assume that the brain uses a general-purpose pattern generator to transform static commands into basic movement segments. We hypothesize that this pattern generator includes an oscillator whose complete cycle generates a single movement segment. In order to demonstrate this hypothesis, we construct an oscillator-based model of movement generation. The model includes an oscillator that generates harmonic outputs whose frequency and amplitudes can be modulated by external inputs. The harmonic outputs drive a number of integrators, each activating a single muscle. The model generates muscle activation patterns composed of rectilinear and harmonic terms. We show that rectilinear and fundamental harmonic terms account for known properties of natural movements, such as the invariant bell-shaped hand velocity profile during reaching. We implement these dynamics by a neural network model and characterize the tuning properties of the neural integrator cells, the neural oscillator cells, and the inputs to the system. Finally, we propose a method to test our hypothesis that a neural oscillator is a central component in the generation of voluntary movement.

Stability of Stepping Movements in the Frontal Plain: A Biomechanical Model

2007 ◽  
Author(s):  
Sonja A. Karg
Keyword(s):  
Muscle Activation ◽  
Biomechanical Model ◽  
Pattern Generator ◽  
Neural Oscillator ◽  
Complex Task ◽  
Activation Patterns ◽  
Muscle Activation Patterns ◽  
Oscillator Network ◽  
Stepping In Place ◽  
Basic Movement

Walking is a complex task influenced by many factors. It is still not well understood how single parts as mechanics, sensor feedback and according control components are integrated to the very robust and adaptive task ‘walking’. So one possible way to address this task is to look at single components, as passive mechanics, and analyze their abilities for walking [1,2]. Or rhythmic movement mechanisms in vertebrates are analyzed, like central pattern generator mechanisms, to produce muscle activation patterns [3]. The combination of mechanics and rhythmic actuation leads to more robust walkers [4]. In the following a new biomechanical model for stepping movements in the frontal plain is introduced. This model bases on passive dynamics actuated by a neural oscillator network. It concentrates on low level generation of basic movement patterns which allow different stepping tasks as stepping in place, stepping up and down or stepping to the side. For the case stepping in place, it is shown that there exist periodic movements which are stable in the sense of a limit cycle, though the movement is varied in frequency and amplitude.

Model of a pattern generator for locomotion in mammals

1985 ◽  
Vol 248 (4) ◽  
pp. R484-R494 ◽  
Author(s):  
A. E. Patla ◽  
T. W. Calvert ◽  
R. B. Stein
Keyword(s):  
Muscle Activation ◽  
Pattern Generator ◽  
Simulation Studies ◽  
Activation Patterns ◽  
Relaxation Oscillators ◽  
Muscle Activation Patterns ◽  
Smooth Change ◽  
Limb Pattern ◽  
Flexion And Extension ◽  
Oscillator Output

This paper presents an analytic model of a limb pattern generator that can produce complex muscle activation patterns such as those shown to control the limbs of cats. The limb pattern generator is considered to have a tonic input and six outputs; this provides for flexion and extension of representative muscles for each of the three joints of the limb. The pattern generator functions as a community of labile synthesized relaxation oscillators that alters its output in response to input. This model was studied using electromyographic data from an experiment conducted on an acute postmammillary cat preparation. The results suggest that the limb pattern generator can be represented as three subsystems: an oscillator that produces the fundamental frequency of the output in response to the tonic signal, nonlinear shaping functions that mold the oscillator output into the basic complex pattern, and appropriate weighting functions that generate the muscle activity pattern from basic waveforms. The model can account for speed changes in locomotion with a relatively smooth change of system parameters. The pattern generator model is generative, amenable to simulation studies, and can be realized by a neural network.

scholarly journals Is the Occurrence of the Sticking Region in Maximum Smith Machine Squats the Result of Diminishing Potentiation and Co-Contraction of the Prime Movers among Recreationally Resistance Trained Males?

2021 ◽  
Vol 18 (3) ◽  
pp. 1366
Author(s):  
Roland van den Tillaar ◽  
Eirik Lindset Kristiansen ◽  
Stian Larsen
Keyword(s):  
Muscle Activity ◽  
Muscle Activation ◽  
Gluteus Maximus ◽  
Knee Extensors ◽  
Force Output ◽  
Activation Patterns ◽  
Muscle Activation Patterns ◽  
Prime Movers ◽  
Almost All ◽  
Height Data

This study compared the kinetics, barbell, and joint kinematics and muscle activation patterns between a one-repetition maximum (1-RM) Smith machine squat and isometric squats performed at 10 different heights from the lowest barbell height. The aim was to investigate if force output is lowest in the sticking region, indicating that this is a poor biomechanical region. Twelve resistance trained males (age: 22 ± 5 years, mass: 83.5 ± 39 kg, height: 1.81 ± 0.20 m) were tested. A repeated two-way analysis of variance showed that Force output decreased in the sticking region for the 1-RM trial, while for the isometric trials, force output was lowest between 0–15 cm from the lowest barbell height, data that support the sticking region is a poor biomechanical region. Almost all muscles showed higher activity at 1-RM compared with isometric attempts (p < 0.05). The quadriceps activity decreased, and the gluteus maximus and shank muscle activity increased with increasing height (p ≤ 0.024). Moreover, the vastus muscles decreased only for the 1-RM trial while remaining stable at the same positions in the isometric trials (p = 0.04), indicating that potentiation occurs. Our findings suggest that a co-contraction between the hip and knee extensors, together with potentiation from the vastus muscles during ascent, creates a poor biomechanical region for force output, and thereby the sticking region among recreationally resistance trained males during 1-RM Smith machine squats.

scholarly journals Electromyographic activation patterns during swallowing in older adults

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jin Young Ko ◽  
Hayoung Kim ◽  
Joonyoung Jang ◽  
Jun Chang Lee ◽  
Ju Seok Ryu
Keyword(s):  
Older Adults ◽  
Viscous Fluid ◽  
Muscle Activation ◽  
Fatty Infiltration ◽  
Liquid Volume ◽  
Type I ◽  
Type Ii ◽  
Activation Patterns ◽  
Muscle Activation Patterns ◽  
Age Related

AbstractAge-related weakness due to atrophy and fatty infiltration in oropharyngeal muscles may be related to dysphagia in older adults. However, little is known about changes in the oropharyngeal muscle activation pattern in older adults. This was a prospective and experimental study. Forty healthy participants (20 older [> 60 years] and 20 young [< 60 years] adults) were enrolled. Six channel surface electrodes were placed over the bilateral suprahyoid (SH), bilateral retrohyoid (RH), thyrohyoid (TH), and sternothyroid (StH) muscles. Electromyography signals were then recorded twice for each patient during swallowing of 2 cc of water, 5 cc of water, and 5 cc of a highly viscous fluid. Latency, duration, and peak amplitude were measured. The activation patterns were the same, in the order of SH, TH, and StH, in both groups. The muscle activation patterns were classified as type I and II; the type I pattern was characterized by a monophasic shape, and the type II comprised a pre-reflex phase and a main phase. The oropharyngeal muscles and SH muscles were found to develop a pre-reflex phase specifically with increasing volume and viscosity of the swallowed fluid. Type I showed a different response to the highly viscous fluid in the older group compared to that in the younger group. However, type II showed concordant changes in the groups. Therefore, healthy older people were found to compensate for swallowing with a pre-reflex phase of muscle activation in response to increased liquid volume and viscosity, to adjust for age-related muscle weakness.

scholarly journals Inter-laboratory comparison of knee biomechanics and muscle activation patterns during gait in patients with knee osteoarthritis

The Knee ◽  
2021 ◽  
Vol 29 ◽  
pp. 500-509
Author(s):  
J.C. Schrijvers ◽  
D. Rutherford ◽  
R. Richards ◽  
J.C. van den Noort ◽  
M. van der Esch ◽  
...  
Keyword(s):  
Knee Osteoarthritis ◽  
Muscle Activation ◽  
Knee Biomechanics ◽  
Activation Patterns ◽  
Muscle Activation Patterns

scholarly journals Functional Gait Recovery after a Combination of Conventional Therapy and Overground Robot-Assisted Gait Training Is Not Associated with Significant Changes in Muscle Activation Pattern: An EMG Preliminary Study on Subjects Subacute Post Stroke

2021 ◽  
Vol 11 (4) ◽  
pp. 448
Author(s):  
Francesco Infarinato ◽  
Paola Romano ◽  
Michela Goffredo ◽  
Marco Ottaviani ◽  
Daniele Galafate ◽  
...  
Keyword(s):  
Conventional Therapy ◽  
Muscle Activation ◽  
Bilateral Symmetry ◽  
Gait Training ◽  
Robot Assisted ◽  
Activation Patterns ◽  
Post Stroke ◽  
Muscle Activation Patterns ◽  
Preliminary Study ◽  
Functional Gait

Background: Overground Robot-Assisted Gait Training (o-RAGT) appears to be a promising stroke rehabilitation in terms of clinical outcomes. The literature on surface ElectroMyoGraphy (sEMG) assessment in o-RAGT is limited. This paper aimed to assess muscle activation patterns with sEMG in subjects subacute post stroke after training with o-RAGT and conventional therapy. Methods: An observational preliminary study was carried out with subjects subacute post stroke who received 15 sessions of o-RAGT (5 sessions/week; 60 min) in combination with conventional therapy. The subjects were assessed with both clinical and instrumental evaluations. Gait kinematics and sEMG data were acquired before (T1) and after (T2) the period of treatment (during ecological gait), and during the first session of o-RAGT (o-RAGT1). An eight-channel wireless sEMG device acquired in sEMG signals. Significant differences in sEMG outcomes were found in the BS of TA between T1 and T2. There were no other significant correlations between the sEMG outcomes and the clinical results between T1 and T2. Conclusions: There were significant functional gains in gait after complex intensive clinical rehabilitation with o-RAGT and conventional therapy. In addition, there was a significant increase in bilateral symmetry of the Tibialis Anterior muscles. At this stage of the signals from the tibialis anterior (TA), gastrocnemius medialis (GM), rectus femoris (RF), and biceps femoris caput longus (BF) muscles of each lower extremity. sEMG data processing extracted the Bilateral Symmetry (BS), the Co-Contraction (CC), and the Root Mean Square (RMS) coefficients. Results: Eight of 22 subjects in the subacute stage post stroke agreed to participate in this sEMG study. This subsample demonstrated a significant improvement in the motricity index of the affected lower limb and functional ambulation. The heterogeneity of the subjects’ characteristics and the small number of subjects was associated with high variability research, functional gait recovery was associated with minimal change in muscle activation patterns.

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