scholarly journals Effects of Perturbation Velocity, Direction, Background Muscle Activation, and Task Instruction on Long-Latency Responses Measured From Forearm Muscles

2021 ◽  
Vol 15 ◽  
Author(s):  
Jacob Weinman ◽  
Paria Arfa-Fatollahkhani ◽  
Andrea Zonnino ◽  
Rebecca C. Nikonowicz ◽  
Fabrizio Sergi
Keyword(s):  
Muscle Activation ◽  
Task Instruction ◽  
Multiple Time Scales ◽  
Behavioral Factors ◽  
Interaction Terms ◽  
Emg Signal ◽  
Long Latency ◽  
Perturbation Velocity ◽  
Latency Response ◽  
And Task

The central nervous system uses feedback processes that occur at multiple time scales to control interactions with the environment. The long-latency response (LLR) is the fastest process that directly involves cortical areas, with a motoneuron response measurable 50 ms following an imposed limb displacement. Several behavioral factors concerning perturbation mechanics and the active role of muscles prior or during the perturbation can modulate the long-latency response amplitude (LLRa) in the upper limbs, but the interactions among many of these factors had not been systematically studied before. We conducted a behavioral study on thirteen healthy individuals to determine the effect and interaction of four behavioral factors – background muscle torque, perturbation direction, perturbation velocity, and task instruction – on the LLRa evoked from the flexor carpi radialis (FCR) and extensor carpi ulnaris (ECU) muscles after velocity-controlled wrist displacements. The effects of the four factors were quantified using both a 0D statistical analysis on the average perturbation-evoked EMG signal in the period corresponding to an LLR, and using a timeseries analysis of EMG signals. All factors significantly modulated LLRa, and their combination nonlinearly contributed to modulating the LLRa. Specifically, all the three-way interaction terms that could be computed without including the interaction between instruction and velocity significantly modulated the LLR. Analysis of the three-way interaction terms of the 0D model indicated that for the ECU muscle, the LLRa evoked when subjects are asked to maintain their muscle activation in response to the perturbations was greater than the one observed when subjects yielded to the perturbations (p < 0.001), but this effect was not measured for muscles undergoing shortening or in absence of background muscle activation. Moreover, higher perturbation velocity increased the LLRa evoked from the stretched muscle in presence of a background torque (p < 0.001), but no effects of velocity were measured in absence of background torque. Also, our analysis identified significant modulations of LLRa in muscles shortened by the perturbation, including an interaction between torque and velocity, and an effect of both torque and velocity. The time-series analysis indicated the significance of additional transient effects in the LLR region for muscles undergoing shortening.

scholarly journals Effects of Perturbation Velocity, Direction, Background muscle activation, and Task Instruction on Long-Latency Responses Measured from Forearm Muscles

2020 ◽  
Author(s):  
Jacob Weinman ◽  
Paria Arfa Fatollahkhani ◽  
Andrea Zonnino ◽  
Rebecca Nikonowicz ◽  
Fabrizio Sergi
Keyword(s):  
Muscle Activation ◽  
Task Instruction ◽  
Multiple Time Scales ◽  
Behavioral Factors ◽  
Interaction Terms ◽  
Emg Signal ◽  
Long Latency ◽  
Perturbation Velocity ◽  
Latency Response ◽  
And Task

AbstractThe centeral nervous system uses feedback processes that occur at multiple time scales to control interactions with the environment. Insight on the neuromechanical mechanisms subserving the faster feedback processes can be gained by applying rapid mechanical perturbations to the limb, and observing the ensuing muscle responses using electromyography (EMG). The long-latency response (LLR) is the fastest process that directly involve cortical areas, with a motorneuron response measurable 50 ms following an imposed limb displacement. Several behavioral factors concerning perturbation mechanics and the active role of muscles prior or during the perturbation can modulate the long-latency response amplitude (LLRa) in the upper limbs, but the interaction between many of these factors had not been systematically studied before.We conducted a behavioral study on thirteen healthy individuals to determine the effect and interaction of four behavioral factors -- background muscle torque, perturbation direction, perturbation velocity, and task instruction -- on the LLRa evoked from the flexor carpi radialis (FCR) and extensor carpi ulnaris (ECU) muscles following the application of wrist displacements. The effects of the four factors listed above were quantified using both a 0D statistical analysis on the average perturbation-evoked EMG signal in the period corresponding to an LLR, and using a timeseries analysis of EMG signals.All factors significantly modulated LLRa, and that their combination nonlinearly contributed to modulating the LLRa. Specifically, all the three-way interaction terms that could be computed without including the interaction between instruction and velocity significantly modulated the LLR. Analysis of the three-way interaction terms of the 0D model indicated that for the ECU muscle, the LLRa evoked when subjects are asked to maintain their muscle activation in response to the perturbations (DNI) was greater than the one observed when subjects yielded (Y) to the perturbations (ΔLLRa — DNI vs. Y: 1.76±0.16 nu, p<0.001), but this effect was not measured for muscles undergoing shortening or in absence of background muscle activation. Moreover, higher perturbation velocity increased the LLRa evoked from the stretched muscle in presence of a background torque (ΔLLRa 200−125 deg/s: 0.94±0.20 nu, p<0.001; ΔLLRa 125−50 deg/s: 1.09 ±0.20 nu, p<0.001), but no effects of velocity were measured in absence of background torque, nor effects of any of those factors was measured on muscles shortened by the perturbations. The time-series analysis indicated the significance of some effects in the LLR region also for muscles undergoing shortening. As an example, the interaction between torque and instruction was significant also for the ECU muscle undergoing shortening, in part due to the composition of a positive and negative modulation of the response due to the interaction between of the two terms. The absence of a nonlinear interaction between task instruction and perturbation velocity suggest that the modulation introduced by these two factors are processed by distinct neural pathways.

scholarly journals Impact of Rhythmic Oral Activity on the Timing of Muscle Activation in the Swallow of the Decerebrate Pig

2009 ◽  
Vol 101 (3) ◽  
pp. 1386-1393 ◽  
Author(s):  
Allan J. Thexton ◽  
A. W. Crompton ◽  
Tomasz Owerkowicz ◽  
Rebecca Z. German
Keyword(s):  
Brain Stem ◽  
Muscle Activation ◽  
Rhythmic Activity ◽  
Emg Activity ◽  
Long Latency ◽  
Jaw Opening ◽  
Short Latency Response ◽  
Pharyngeal Swallow ◽  
Latency Response ◽  
Changeover Period

The pharyngeal swallow can be elicited as an isolated event but, in normal animals, it occurs within the context of rhythmic tongue and jaw movement (RTJM). The response includes activation of the multifunctional geniohyoid muscle, which can either protract the hyoid or assist jaw opening; in conscious nonprimate mammals, two bursts of geniohyoid EMG activity (GHemg) occur in swallow cycles at times consistent with these two actions. However, during experimentally elicited pharyngeal swallows, GHemg classically occurs at the same time as hyoglossus and mylohyoid activity (short latency response) but, when the swallow is elicited in the decerebrate in the absence of RTJM, GHemg occurs later in the swallow (long latency response). We tested the hypothesis that it was not influences from higher centers but a brain stem mechanism, associated with RTJM, which caused GHemg to occur earlier in the swallow. In 38 decerebrate piglets, RTJM occurred sporadically in seven animals. Before RTJM, GHemg had a long latency, but, during RTJM, swallow related GHemg occurred synchronously with activity in hyoglossus and mylohyoid, early in the swallow. Both early and late responses were present during the changeover period. During this changeover period, duplicate electrodes in the geniohyoid could individually detect either the early or the late burst in the same swallow. This suggested that two sets of geniohyoid task units existed that were potentially active in the swallow and that they were differentially facilitated or inhibited depending on the presence or absence of rhythmic activity originating in the brain stem.

Differences in muscular activation and fatigue for intermittent and constant load

2005 ◽  
Vol 5 (1) ◽  
pp. 43-56
Author(s):  
Danuta Roman-Liu ◽  
Krzysztof Kȩdzior
Keyword(s):  
External Force ◽  
Upper Limb ◽  
Muscle Activation ◽  
Regression Line ◽  
Constant Load ◽  
Median Frequency ◽  
Experimental Conditions ◽  
Emg Signal ◽  
Limb Posture ◽  
Muscular Activation

The aim of this study was to compare the influence of constant or intermittent load on muscle activation and fatigue. The analysis and assessment of muscular activation and fatigue was based on surface EMG measurements from eight muscles (seven muscles of the right upper limb and trapezius muscle). Two EMG signal parameters were analyzed for each of the experimental conditions distinguished by the value of the external force and the character of the load – constant or intermittent. The amplitude related to its maximum (AMP) and the slope of the regression line between time and median frequency (SMF) were the EMG parameters that were analyzed. The results showed that constant load caused higher muscular fatigue than intermittent load despite the lower value of the external force and lower muscle activation. Results suggest that additional external force might influence muscle activation and fatigue more than upper limb posture. The results of the study support the thesis that all biomechanical factors which influence upper limb load and fatigue (upper limb posture, external force and time sequences) should be considered when work stands and work processes are designed. They also indicate that constant load should be especially avoided.

Evaluation of Muscle Activities on Different Type of Exercises During Prolonged Sitting

2021 ◽  
Vol 2 (2) ◽  
Author(s):  
Mohammad Shahril Salim ◽  
◽  
Nor Fatihah Fujrah Mohd Nawi ◽  
Ahmad Faizal Salleh ◽  
Nurhidayah Omar ◽  
...  
Keyword(s):  
Back Pain ◽  
Muscle Activation ◽  
Erector Spinae ◽  
Prolonged Sitting ◽  
Emg Signal ◽  
Different Types ◽  
Muscle Activations ◽  
Internal Oblique ◽  
Electrical Muscle

Electromyography (EMG) signal is an analysis of electrical signals generated during muscular contractions that have been used to measure and record electrical muscle activity usually applied for medical tests. In this research EMG signal is used to; (1) evaluate muscle activations on different gender during prolonged sitting task; (2) investigate the influence of various types of exercise during prolonged sitting on muscle activation and (3) proposed the best exercise that can help to prevent low back discomfort. Twenty subjects (10 males and 10 females) were recruited from undergraduate engineering student’s education background in UniMAP with age ranging between 20 to 24 years old. The subject must be asymptomatic back pain, normal BMI and right-handed. . Three different types of sitting, one hour per sitting were done by each subject in order to reach the goals of this study. First sitting (sitting without exercise) was conducted while second and third sitting (sitting with exercise) were done in order the investigate the effectiveness of the exercises. Two different types of exercise were performed in second and third sitting, both of exercises were chosen from Mc Kenzie’s exercise. EEGOTM sport device were used to record the EMG signal from four types of muscles which are Erector Spinae, Latissimus Dorsi, Internal Oblique and External Oblique. By comparing the Root Mean Square (RMS) values from EMG signals muscle activation during prolonged sitting and the effectiveness of performing the exercises have been evaluated based on RMS values. As the results, muscle become deactivate during prolonged sitting. The best exercise to reduce back pain discomfort is exercise type 1 (Seated Lumbar Exercise) and it is recommended to perform this exercise regularly to reduce the risk of getting hazardous disease due to prolonged sitting.

scholarly journals Transient Responses of Rabbit Retinal Ganglion Cells to Photic and Electrical Stimuli

1976 ◽  
Vol 3 (1) ◽  
pp. 73-79 ◽  
Author(s):  
S. Molotchnikoff
Keyword(s):  
Receptive Field ◽  
Retinal Ganglion Cells ◽  
Ganglion Cells ◽  
Electrical Activation ◽  
Retinal Ganglion ◽  
Transient Responses ◽  
Long Latency ◽  
Latency Response ◽  
Electrical Stimuli ◽  
Inhibitory Period

SUMMARY:The relationships between the center and the surround of the receptive field of the rabbit retinal ganglion cell were investigated. This was done by coupling localized light spots and electrical activation of the retina and by analyzing the time of the excitatory and inhibitory periods. The responsiveness to the electrical transretinal pulse revealed a) that ON stimulation in OFF-center cells and OFF stimulation in ON-center cells, elicited a primary period of inhibition with a short latency; b) the long latency response of surround stimulation was not preceded by an inhibitory period unless the center was simultaneously stimulated in the same direction; c) a transient response to a stationary spot of light is followed by a period of inhibition. These results are discussed in relation to the known cellular retinal networks.

scholarly journals Effects of a Dynamic Chair on Chair Seat Motion and Trunk Muscle Activity during Office Tasks and Task Transitions

2018 ◽  
Vol 15 (12) ◽  
pp. 2723 ◽  
Author(s):  
Corina Nüesch ◽  
Jan-Niklas Kreppke ◽  
Annegret Mündermann ◽  
Lars Donath
Keyword(s):  
Young Adults ◽  
Muscle Activity ◽  
Muscle Activation ◽  
Dynamic Condition ◽  
Trunk Muscle ◽  
Erector Spinae ◽  
Task Transition ◽  
The Right ◽  
Hand Writing ◽  
And Task

Employing dynamic office chairs might increase the physical (micro-) activity during prolonged office sitting. We investigated whether a dynamic BioSwing® chair increases chair sway and alters trunk muscle activation. Twenty-six healthy young adults performed four office tasks (reading, calling, typing, hand writing) and transitions between these tasks while sitting on a dynamic and on a static office chair. For all task-transitions, chair sway was higher in the dynamic condition (p < 0.05). Muscle activation changes were small with lower mean activity of the left obliquus internus during hand writing (p = 0.07), lower mean activity of the right erector spinae during the task-transition calling to hand writing (p = 0.036), and higher mean activity of the left erector spinae during the task-transition reading to calling (p = 0.07) on the dynamic chair. These results indicate that an increased BioSwing® chair sway only selectively alters trunk muscle activation. Adjustments of chair properties (i.e., swinging elements, foot positioning) are recommended.

scholarly journals Temporal Evolution of “Automatic Gain-Scaling”

2009 ◽  
Vol 102 (2) ◽  
pp. 992-1003 ◽  
Author(s):  
J. Andrew Pruszynski ◽  
Isaac Kurtzer ◽  
Timothy P. Lillicrap ◽  
Stephen H. Scott
Keyword(s):  
Steady State ◽  
Muscle Activity ◽  
Temporal Evolution ◽  
Rapid Decrease ◽  
Short Latency ◽  
State Activity ◽  
Long Latency ◽  
Short Latency Response ◽  
Latency Response ◽  
Steady State Activity

The earliest neural response to a mechanical perturbation, the short-latency stretch response (R1: 20–45 ms), is known to exhibit “automatic gain-scaling” whereby its magnitude is proportional to preperturbation muscle activity. Because gain-scaling likely reflects an intrinsic property of the motoneuron pool (via the size-recruitment principle), counteracting this property poses a fundamental challenge for the nervous system, which must ultimately counter the absolute change in load regardless of the initial muscle activity (i.e., show no gain-scaling). Here we explore the temporal evolution of gain-scaling in a simple behavioral task where subjects stabilize their arm against different background loads and randomly occurring torque perturbations. We quantified gain-scaling in four elbow muscles (brachioradialis, biceps long, triceps lateral, triceps long) over the entire sequence of muscle activity following perturbation onset—the short-latency response, long-latency response (R2: 50–75 ms; R3: 75–105 ms), early voluntary corrections (120–180 ms), and steady-state activity (750–1250 ms). In agreement with previous observations, we found that the short-latency response demonstrated substantial gain-scaling with a threefold increase in background load resulting in an approximately twofold increase in muscle activity for the same perturbation. Following the short-latency response, we found a rapid decrease in gain-scaling starting in the long-latency epoch (∼75-ms postperturbation) such that no significant gain-scaling was observed for the early voluntary corrections or steady-state activity. The rapid decrease in gain-scaling supports our recent suggestion that long-latency responses and voluntary control are inherently linked as part of an evolving sensorimotor control process through similar neural circuitry.

Evaluation and optimization of vehicle pedal comfort based on biomechanics

2019 ◽  
Vol 234 (5) ◽  
pp. 1402-1412
Author(s):  
Liqing Chen ◽  
Wanjun Li ◽  
Yang Yang ◽  
Wei Miao
Keyword(s):  
Muscle Activation ◽  
Resistance Coefficient ◽  
Lower Limbs ◽  
Accelerator Pedal ◽  
Noticeable Effect ◽  
The Road ◽  
Emg Signal ◽  
Optimal Value ◽  
The Difference ◽  
Point Distance

Existing research on the manipulation comfort of the cab pedal generally focuses on the completion of the pedal movement when a vehicle is at rest, with certain data collected for analysis. This paper, by taking passenger vehicles in China as the study object and in view of the actual road conditions in China and the Chinese body size, attempts to solve the problem of muscle redundancy through the maximum/minimum optimization model of muscle activation. The road test was carried out on a typical pavement in a Chinese city. The parameters of pedal stroke, pedal force, and typical Electromyography signal (EMG) signal of drivers’ lower limbs during driving were obtained, from which muscle activation degree was calculated. The obtained experimental data were used as external driving one to simulate and analyze the pedal comfort under the layout of different human percentile and different pedal parameters in an aim to obtain the optimal value. The results indicate that the difference in pedal strokes, pedal preload, pedal resistance coefficients, seat heights, and H-point distances can have a noticeable effect on muscle activation. Taking a 95th-percentile accelerator pedal as an example, with the optimal values of each parameter selected (pedal preload: 8.2 N, pedal resistance coefficient: 2.55, seat height: 0.45 m and H-point distance: 0.86 m), as the pedal strokes increase, muscle activation shows a trend of increase after initial decrease. In the common stroke of a pedal after optimization, the degree of muscle activation is significantly lower than that before optimization, indicating a decrease in muscle fatigue.

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