Dysequilibrium Reaction Time and “Long-Loop” Recruitment Deficits in Subjects with Hemiplegia

1992 ◽  
Vol 12 (4) ◽  
pp. 229-241
Author(s):  
Richard P. DiFabio ◽  
Mary Beth Badke ◽  
Ann Breunig
Keyword(s):  
Reaction Time ◽  
Stretch Reflex ◽  
Onset Time ◽  
Reflex Response ◽  
Body Sway ◽  
Limiting Factor ◽  
Postural Reflex ◽  
Time Required ◽  
Gastrocnemius Muscles ◽  
Postural Muscles

Gaps in the recruitment of postural muscles to correct body sway may be a limiting factor in the rehabilitation of patients with stroke. The purpose of this study was to determine how the onset of a postural reflex compares to the conscious identification of body sway in patients with hemiplegia and in a comparison group of able-bodied subjects. All subjects stood on a movable force platform that was unexpectedly displaced backwards inducing a forward body sway. The excursion and velocity of the platform displacements were varied systematically and the frequency of activation of postural muscles was recorded. A hand held response key was used to measure the time required to react to the postural disturbance (RT). In addition, the onset time of a long-loop “stretch” reflex was measured in the gastrocnemius muscles bilaterally. Subjects with hemiplegia failed to recruit a reflex response in 53% of the trials, whereas able-bodied subjects had an absent response in only 3% of the trials. The upper extremity RT for subjects with hemiplegia was not significantly delayed compared to able-bodied subjects, and the onset of a stretch reflex response in the gastrocnemius muscles was not different between groups. In addition, there was no correlation between reflex onset and conscious reaction time for control or disabled groups. These results have implications for the practice of occupational therapy because lower extremity recruitment deficits may persist and require treatment even though the recognition of body sway and the onset of reflex muscle discharge (when recruited) was similar to that of able-bodied subjects.

scholarly journals THE LIGHT GROWTH RESPONSE AND THE GROWTH SYSTEM OF PHYCOMYCES

1935 ◽  
Vol 18 (3) ◽  
pp. 385-397 ◽  
Author(s):  
E. S. Castle ◽  
A. J. M. Honeyman
Keyword(s):  
Reaction Time ◽  
Growth Response ◽  
Total Elongation ◽  
Limiting Factor ◽  
Outermost Layer ◽  
Long Latency ◽  
Time Component ◽  
Growth System ◽  
Time Required ◽  
Mechanism Of Growth

1. The Roscoe-Bunsen law holds for the light growth response of Phycomyces if the time component of stimulation is short. With exposures longer than a few seconds, the reaction time to light is determined by the intensity and not by the energy of the flash. 2. The possible nature of the very long latency in the response to light is considered in terms of the structure of the cell and its mechanism of growth. It is suggested that during the latency some substance produced by light in the protoplasm is transported centrifugally to the cell wall or outermost layer of protoplasm. 3. The total elongation occurring over a period of 1 to 2 hours is independent of flashes of light or temporary darkening. Light acts by facilitating some change already under way in the growth system, and during the principal phase of elongation is not a necessary or limiting factor for growth. 4. Judged by the reaction time, the original sensitivity is restored in the light system following exposure to light in about one-third the time required for equilibrium to be reattained in the growth system.

Residual Neuromuscular Block in HIV-Infected Young Patients: A Prospective Observational Study

2021 ◽  
Author(s):  
Ruixue hou ◽  
Liangyu wu ◽  
Yadong liu ◽  
Fangfang miao ◽  
Cheng yin ◽  
...  
Keyword(s):  
Reaction Time ◽  
Neuromuscular Block ◽  
Young Patients ◽  
Onset Time ◽  
Pulmonary Complications ◽  
Infected Group ◽  
Normal Group ◽  
Postanesthesia Care Unit ◽  
Residual Neuromuscular Blockade ◽  
Train Of Four

Abstract Objectives: Avoidance of residual neuromuscular blockade (RNMB) is crucial to decrease anesthesia-related pulmonary complications. At present, no data are available for HIV-infected patients about the occurrence of RNMB. In this trial, we aim to investigate the incidence of RNMB in such patients. Methods: Data were prospectively collected on 45 normal and 45 HIV-infected patients (18-65 yr). The train-of-four stimulation (TOF-Watch SX) was used to evaluate the level of neuromuscular block from the induction of anesthesia to back to the postanesthesia care unit (PACU) by an assessor, but blind to the anesthesiologist. Primary endpoint was the presence of RNMB at PACU admission, defined as a train-of-four (TOF) ratio < 0.9. The onset time (from application of cisatracurium to maximum depression of T1), no reaction time (from zero of T1 to non-zero), and clinical duration (from application to 25% recovery of T1) were determined for each patient. Results: The incidence of RNMB was 37.5% in HIV- infected patients and 32.5% in normal patients (difference, 5%; 99% CI, −16% to 26 1%; p=0.815). The onset time was no different between two groups (4.05±0.88 min in HIV-infected group vs. 3.85±1.08 min in normal group (p=0.37)). The no reaction time was also similarly between two groups ( 49.83±3.81min in HIV-infected group vs. 48.98±5.12min in normal group (p=0.40)). The clinical duration was 53.78±3.05 min and 52.40±5.02 min in HIV-infected group and normal group, respectively (p=0.14). Conclusion: The odds of RNMB were not significantly different in HIV-infected young patients compared to normal persons.

QUANTIFIED DEEP TENDON REFLEX DEVICE, SECOND GENERATION

2008 ◽  
Vol 08 (01) ◽  
pp. 75-85 ◽  
Author(s):  
ROBERT LEMOYNE ◽  
FOAD DABIRI ◽  
ROOZBEH JAFARI
Keyword(s):  
Traumatic Brain Injury ◽  
Brain Injury ◽  
Stretch Reflex ◽  
Evaluation System ◽  
Deep Tendon Reflex ◽  
Reflex Response ◽  
Fundamental Aspect ◽  
Maximum Acceleration ◽  
Mems Accelerometer ◽  
Tendon Reflex

The deep tendon reflex is a fundamental aspect of neurological examinations. The severity of and degree of recovery from a traumatic brain injury can be assessed by the myotatic stretch reflex. A hyperactive reflex response is correlated with spasticity, which can also be correlated with the degree of damage to the supraspinal input, in essence assessing the severity of traumatic brain injury. The myotatic stretch reflex is clinically evaluated by the National Institute of Neurological Disorders and Stroke (NINDS) reflex scale (0–4); however, this scale lacks temporal data and may also vary in interpretation. The solution is a fully quantified evaluation system of the myotatic stretch reflex, whereby a patellar hammer's force input is based on original potential energy and a microelectromechanical system (MEMS) accelerometer quantifies the output. The MEMS accelerometer is attached to a set anchor point near the ankle. The reflex amplitude is based on the maximum acceleration of the reflex response. The quantified data collected from MEMS accelerometers are transmitted by a portable computer (i.e. a Pocket PC). This paper describes a device that quantitatively evaluates the reflex response using accelerometers and that demonstrates precision for reproducibility.

scholarly journals Smart Headgear for Assessment of Auditory Response Reaction Time of Professional and Amateur Kendokas

Proceedings ◽  
2020 ◽  
Vol 49 (1) ◽  
pp. 93
Author(s):  
Kwangyul Jeong ◽  
Adin Ming Tan ◽  
Yehuda Weizman ◽  
Franz Konstantin Fuss
Keyword(s):  
Reaction Time ◽  
Pressure Sensor ◽  
Average Reaction Time ◽  
Significant Difference ◽  
Auditory Response ◽  
Time Required

In Kendo, the ability to execute a technique within the shortest time is essential for winning. The purpose of this study was to utilise an in-house developed automatic headgear-scoring sensor with a buzzer to determine the auditory response reaction time (ARRT) of professional (PK) and amateur (AK) Kendo practitioners. ARRT is defined as the time required for a participant to hit a target after a buzzer is sounded. A total of 14 participants took part in this study. The participants were requested to hit the opponent’s headgear target, which consisted of a pressure sensor, upon hearing the buzzer. The average reaction time of PK is 0.44 s, and for AK 0.58 s, with a significant difference between the two groups (p < 0.0001). The in-house developed automatic headgear-scoring sensor with buzzer can be utilised to assist a Kendo practitioner in training to shorten the response reaction time to improve competition performance.

Contributions of motor-unit recruitment and rate modulation of compensation for muscle yielding

1982 ◽  
Vol 47 (5) ◽  
pp. 797-809 ◽  
Author(s):  
P. J. Cordo ◽  
W. Z. Rymer
Keyword(s):  
Motor Unit ◽  
Stretch Reflex ◽  
Muscle Force ◽  
Motor Units ◽  
Muscle Stiffness ◽  
Motor Unit Recruitment ◽  
Reflex Response ◽  
Rate Modulation ◽  
Stimulus Rate ◽  
Wide Range

1. Subdivided portions of the cut ventral root innervation of the soleus muscle were electrically stimulated in 14 anesthetized cats. The stimulus trains imposed on these nerves simulated the recruitment and rate-modulation patterns of single motor units recorded during stretch-reflex responses in decerebrate preparations. Each activation pattern was evaluated for its ability to prevent muscle yield. 2. Three basic stimulus patterns, recruitment, step increases in stimulus rate, and doublets were imposed during the course of ramp stretches applied over a wide range of velocities. The effect of each stimulus pattern on muscle force was compared to the force output recorded without stretch-related recruitment or rate modulation. 3. Motor-unit recruitment was found to be most effective in preventing yield during muscle stretch. Newly recruited motor units showed no evidence of yielding for some 250 ms following activation, at which time muscle stiffness declined slightly. This time-dependent resistance to yield was observed regardless of whether the onset of the neural stimulus closely preceded or followed stretch onset. 4. Step increases in stimulus rate arising shortly after stretch onset did not prevent the occurrence of yield at most stretch velocities, but did augment muscle stiffness later in the stretch. Doublets in the stimulus train were found to augment muscle stiffness only when they occurred in newly recruited motor units. 5. These results suggest that at low or moderate initial forces, the prevention of yield in lengthening, reflexively intact muscle results primarily from rapid motor-unit recruitment. To a lesser extent, the spring-like character of the stretch-reflex response also derives from step increases in firing rate of motor units active before stretch onset and doublets in units recruited during the course of stretch. Smooth rate increases appear to augment muscle force later in the course of the reflex response.

scholarly journals Effect of Low-Frequency Vibration on Muscle Response under Different Neurointact Conditions

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Chaofei Zhang ◽  
Wenjun Wang ◽  
Dennis Anderson ◽  
Sishu Guan ◽  
Guofa Li ◽  
...  
Keyword(s):  
Stretch Reflex ◽  
Muscle Force ◽  
Low Frequency ◽  
Quantitative Relationship ◽  
Length Change ◽  
Whole Body ◽  
Sprague Dawley ◽  
Nonlinear Hysteresis ◽  
Low Frequency Vibration ◽  
Gastrocnemius Muscles

Stretch reflex is an important factor that influences the biomechanical response of the human body under whole-body vibration. However, there is a lack of quantitative evaluation at lower frequencies. Thus, the aim of this study was to investigate the effects of vibration on the stretch reflex and, in particular, to explore the quantitative relationship between dynamic muscle responses and low-frequency vibrations. The gastrocnemius muscle of 45 Sprague-Dawley rats was dissected. Sinusoidal vibrations of five discrete frequencies (2~16 Hz) with peak-to-peak amplitudes of 1 mm were applied to the gastrocnemius muscles with 2 mm or 3 mm prelengthening. Variables including dynamic muscle force, vibration acceleration, and displacement were recorded in two conditions, with and without the stretch reflex. Results showed that the dynamic muscle forces decreased by 20% on average for the 2 mm prelengthening group after the stretch reflex was blocked and by 24% for the 3 mm prelengthening group. Statistical analysis indicated that the amplitude of dynamic muscle force in the “with stretch reflex” condition was significantly larger than that in the “without stretch reflex” condition (p<0.001). The tension-length curve was found to be a nonlinear hysteresis loop that changed with frequency. The phase difference between the dynamic muscle force and the length change was affected significantly by vibration frequency (p<0.01), and the minimum frequency was 4–8 Hz. Experimental results of this study could benefit musculoskeletal model by providing a theoretical support to build a stretch reflex model for low-frequency vibration.

scholarly journals University of Miami Radiocarbon Dates VI

Radiocarbon ◽  
1976 ◽  
Vol 18 (2) ◽  
pp. 210-220 ◽  
Author(s):  
J J Stipp ◽  
K L Eldridge ◽  
R Cadwell
Keyword(s):  
Standard Deviation ◽  
Reaction Time ◽  
Liquid Scintillation Counting ◽  
Liquid Scintillation ◽  
Scintillation Counting ◽  
Correction Factors ◽  
Lithium Metal ◽  
Radiocarbon Dates ◽  
Partial List ◽  
Time Required

The following radiocarbon measurements are a partial list of projects and samples dated since the Spring of 1975. The technique used is liquid scintillation counting of wholly synthesized benzene as indicated in R, v 16, p 402-408. The intermediate chemical step of converting CO2 to Li2C2 has been modified so that the CO2 is reacted with the lithium metal at a temperature of 950° to 1000°C instead of the 600°C as formerly done (Tamers, 1975). This modification has had the effect of reducing occasional variable losses in conversion yields in this step, and reducing the reaction time required from 30 min to 10 min for a typical ¼ mole sample. Dates are calculated using a 14C half-life of 5568 yr and errors are reported as one standard deviation. No other correction factors are applied.

scholarly journals Flèche versus Lunge as the Optimal Footwork Technique in Fencing

2019 ◽  
Vol 16 (13) ◽  
pp. 2315 ◽  
Author(s):  
Zbigniew Borysiuk ◽  
Natalia Markowska ◽  
Mariusz Konieczny ◽  
Krzysztof Kręcisz ◽  
Monika Błaszczyszyn ◽  
...  
Keyword(s):  
Reaction Time ◽  
Movement Time ◽  
Medial Gastrocnemius ◽  
Ground Reaction Forces ◽  
Vertical Force ◽  
Muscular Tension ◽  
Explosive Force ◽  
Reaction Forces ◽  
Gastrocnemius Muscles ◽  
Sensorimotor Responses

The objective of the study reported in this paper involved identifying the fencing attack (flèche versus lunge) that provides greater effectiveness in a real competition. Two hypotheses are presented in the study. The first hypothesis involves the greater effectiveness of the flèche with regard to bioelectric muscular tension, and the second hypothesis involves the reduction of movement time of the flèche. Therefore, analyses were conducted by the application of EMG (electromyography) signal, ground reaction forces, and parameters representing sensorimotor responses (RT—reaction time and MT—movement time). This study included six world-leading female épée fencers (mean age: 24.6 ± 6.2 years). Throughout the procedure, the subjects performed flèche and lunge touches at the command of the coach based on visual stimuli. The experimental results indicated the greater effectiveness of the flèche compared with the lunge with regard to increases in EMG values (p = 0.027) in the lateral and medial gastrocnemius muscles and decreases in the duration of the movement phase (p = 0.049) and vertical force of the rear leg (p = 0.028). In conclusion, higher levels of EMG and ground reaction forces were generated during the flèche compared with the lunge, which promotes an improvement in the explosive force and contributes to a reduction in the movement phase of the entire offensive action.

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