Head-Trunk Coordination During Linear Anterior-Posterior Translations

2003 ◽  
Vol 89 (4) ◽  
pp. 1891-1901 ◽  
Author(s):  
Emily A. Keshner
Keyword(s):  
Vestibular System ◽  
Healthy Subjects ◽  
Low Frequency ◽  
Head Acceleration ◽  
Response Latencies ◽  
Distraction Task ◽  
Analysis System ◽  
Post Hoc ◽  
Linear Accelerometer ◽  
Anterior Posterior

The purpose of this study was to evaluate the relative contributions of inputs from the vestibular system and the trunk to head-trunk coordination. Twelve healthy adults and 6 adults with diminished bilateral labyrinthine input (LD) were seated with their trunk either fixed to the seat or free to move. Subjects received 10-cm, 445-cm/s2 anterior-posterior ramps and 0.35- to 4.05-Hz sum-of-sines translations while performing a mental distraction task in the dark. Kinematics of the head and trunk were derived from an Optotrak motion analysis system and a linear accelerometer placed on the head. EMG signals were collected from neck and paraspinal muscles. Data were tested for significance with multivariate ANOVA (MANOVA) and Bonferroni post hoc analyses. Initial linear and angular head acceleration directions differed in healthy subjects when the trunk was fixed or free, but did not differ in LD subjects. Peak head angular accelerations were significantly greater with the trunk fixed than when free, and were greater in LD than in control subjects. EMG response latencies did not differ when the trunk was fixed or free. Low-frequency phase responses in the healthy subjects were close to 90° and had a delayed descent as frequency increased, suggesting some neural compensation that was absent in the LD subjects. Results of this study revealed a strong initial reliance on system mechanics and on signals from segmental receptors. The vestibular system may act to damp later response components and to monitor the position of the head in space secondary to feedback from segmental proprioceptors rather than to generate the postural reactions.

Effects of activation frequency and force on low-frequency fatigue in human skeletal muscle

1999 ◽  
Vol 86 (4) ◽  
pp. 1337-1346 ◽  
Author(s):  
Stuart A. Binder-Macleod ◽  
David W. Russ
Keyword(s):  
Healthy Subjects ◽  
Human Skeletal Muscle ◽  
Low Frequency ◽  
Variable Frequency ◽  
Activation Pattern ◽  
Constant Frequency ◽  
Mean Frequency ◽  
Before And After ◽  
Low Frequency Fatigue ◽  
Force Time

No comparison of the amount of low-frequency fatigue (LFF) produced by different activation frequencies exists, although frequencies ranging from 10 to 100 Hz have been used to induce LFF. The quadriceps femoris of 11 healthy subjects were tested in 5 separate sessions. In each session, the force-generating ability of the muscle was tested before and after fatigue and at 2, ∼13, and ∼38 min of recovery. Brief (6-pulse), constant-frequency trains of 9.1, 14.3, 33.3, and 100 Hz and a 6-pulse, variable-frequency train with a mean frequency of 14.3 Hz were delivered at 1 train/s to induce fatigue. Immediately postfatigue, there was a significant effect of fatiguing protocol frequency. Muscles exhibited greater LFF after stimulation with the 9.1-, 14.3-, and variable-frequency trains. These three trains also produced the greatest mean force-time integrals during the fatigue test. At 2, ∼13, and ∼38 min of recovery, however, the LFF produced was independent of the fatiguing protocol frequency. The findings are consistent with theories suggesting two independent mechanisms behind LFF and may help identify the optimal activation pattern when functional electrical stimulation is used.

scholarly journals Effect of Acupuncture on Heart Rate Variability: A Systematic Review

2014 ◽  
Vol 2014 ◽  
pp. 1-19 ◽  
Author(s):  
Joanne W. Y. Chung ◽  
Vincent C. M. Yan ◽  
Hongwei Zhang
Keyword(s):  
Systematic Review ◽  
Heart Rate ◽  
Heart Rate Variability ◽  
High Frequency ◽  
Healthy Subjects ◽  
Keyword Search ◽  
Data Extraction ◽  
Meta Analysis ◽  
Low Frequency ◽  
Control Group

Aim.To summarize all relevant trials and critically evaluate the effect of acupuncture on heart rate variability (HRV).Method.This was a systematic review with meta-analysis. Keyword search was conducted in 7 databases for randomized controlled trials (RCTs). Data extraction and risk of bias were done.Results.Fourteen included studies showed a decreasing effect of acupuncture on low frequency (LF) and low frequency to high frequency ratio (LF/HF ratio) of HRV for nonhealthy subjects and on normalized low frequency (LF norm) for healthy subjects. The overall effect was in favour of the sham/control group for high frequency (HF) in nonhealthy subjects and for normalized high frequency (HF norm) in healthy subjects. Significant decreasing effect on HF and LF/HF ratio of HRV when acupuncture was performed on ST36 among healthy subjects and PC6 among both healthy and nonhealthy subjects, respectively.Discussion.This study partially supports the possible effect of acupuncture in modulating the LF of HRV in both healthy and nonhealthy subjects, while previous review reported that acupuncture did not have any convincing effect on HRV in healthy subjects. More published work is needed in this area to determine if HRV can be an indicator of the therapeutic effect of acupuncture.

scholarly journals Estimation of Delay Times in Coupling Between Autonomic Regulatory Loops of Human Heart Rate and Blood Flow Using Phase Dynamics Analysis

2017 ◽  
Vol 9 (1) ◽  
pp. 16-22 ◽  
Author(s):  
Vladimir S Khorev ◽  
Anatoly S Karavaev ◽  
Elena E Lapsheva ◽  
Tatyana A Galushko ◽  
Mikhail D Prokhorov ◽  
...  
Keyword(s):  
Heart Rate ◽  
Delay Time ◽  
Healthy Subjects ◽  
Low Frequency ◽  
Phase Dynamics ◽  
Oscillatory Systems ◽  
Low Frequency Oscillations ◽  
Delay Times ◽  
The Difference ◽  
Regulatory Loop

Objective: We assessed the delay times in the interaction between the autonomic regulatory loop of Heart Rate Variability (HRV) and autonomic regulatory loop of photoplethysmographic waveform variability (PPGV), showing low-frequency oscillations. Material and Methods: In eight healthy subjects aged 25–30 years (3 male, 5 female), we studied at rest (in a supine position) the simultaneously recorded two-hour signals of RR intervals (RRIs) chain and finger photoplethysmogram (PPG). To extract the low-frequency components of RRIs and PPG signal, associated with the low-frequency oscillations in HRV and PPGV with a frequency of about 0.1 Hz, we filtered RRIs and PPG with a bandpass 0.05-0.15 Hz filter. We used a method for the detection of coupling between oscillatory systems, based on the construction of predictive models of instantaneous phase dynamics, for the estimation of delay times in the interaction between the studied regulatory loops. Results: Averaged value of delay time in coupling from the regulatory loop of HRV to the loop of PPGV was 0.9±0.4 seconds (mean ± standard error of the means) and averaged value of delay time in coupling from PPGV to HRV was 4.1±1.1 seconds. Conclusion: Analysis of two-hour experimental time series of healthy subjects revealed the presence of delay times in the interaction between regulatory loops of HRV and PPGV. Estimated delay time in coupling regulatory loops from HRV to PPGV was about one second or even less, while the delay time in coupling from PPGV to HRV was about several seconds. The difference in delay times is explained by the fact that PPGV to HRV response is mediated through the autonomic nervous system (baroreflex), while the HRV to PPGV response is mediated mechanically via cardiac output.

Age dependency of cardiovascular autonomic responses to head-up tilt in healthy subjects

2004 ◽  
Vol 96 (6) ◽  
pp. 2333-2340 ◽  
Author(s):  
Tomi Laitinen ◽  
Leo Niskanen ◽  
Ghislaine Geelen ◽  
Esko Länsimies ◽  
Juha Hartikainen
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
High Frequency ◽  
Healthy Subjects ◽  
Baroreflex Sensitivity ◽  
Low Frequency ◽  
Upright Position ◽  
Vascular Responses ◽  
Autonomic Responses ◽  
Head Up Tilt

In elderly subjects, heart rate responses to postural change are attenuated, whereas their vascular responses are augmented. Altered strategy in maintaining blood pressure homeostasis during upright position may result from various cardiovascular changes, including age-related cardiovascular autonomic dysfunction. This exploratory study was conducted to evaluate impact of age on cardiovascular autonomic responses to head-up tilt (HUT) in healthy subjects covering a wide age range. The study population consisted of 63 healthy, normal-weight, nonsmoking subjects aged 23–77 yr. Five-minute electrocardiogram and finger blood pressure recordings were performed in the supine position and in the upright position 5 min after 70° HUT. Stroke volume was assessed from noninvasive blood pressure signals by the arterial pulse contour method. Heart rate variability (HRV) and systolic blood pressure variability (SBPV) were analyzed by using spectral analysis, and baroreflex sensitivity (BRS) was assessed by using sequence and cross-spectral methods. Cardiovascular autonomic activation during HUT consisted of decreases in HRV and BRS and an increase in SBPV. These changes became attenuated with aging. Age correlated significantly with amplitude of HUT-stimulated response of the high-frequency component ( r = -0.61, P < 0.001) and the ratio of low-frequency to high-frequency power of HRV ( r = -0.31, P < 0.05) and indexes of BRS (local BRS: r = -0.62, P < 0.001; cross-spectral baroreflex sensitivity in the low-frequency range: r = -0.38, P < 0.01). Blood pressure in the upright position was maintained well irrespective of age. However, the HUT-induced increase in heart rate was more pronounced in the younger subjects, whereas the increase in peripheral resistance was predominantly observed in the older subjects. Thus it is likely that whereas the dynamic capacity of cardiac autonomic regulation decreases, vascular responses related to vasoactive mechanisms and vascular sympathetic regulation become augmented with increasing age.

scholarly journals The effect of cannabidiol (CBD) on low-frequency activity and functional connectivity in the brain of adults with and without autism spectrum disorder (ASD)

2019 ◽  
Vol 33 (9) ◽  
pp. 1141-1148 ◽  
Author(s):  
Charlotte M Pretzsch ◽  
Bogdan Voinescu ◽  
Maria A Mendez ◽  
Robert Wichers ◽  
Laura Ajram ◽  
...  
Keyword(s):  
Autism Spectrum Disorder ◽  
Functional Connectivity ◽  
Low Frequency ◽  
Random Order ◽  
Autism Spectrum ◽  
Spectrum Disorder ◽  
Double Blind ◽  
Drug Challenge ◽  
The Right ◽  
Post Hoc

Background: The potential benefits of cannabis and its major non-intoxicating component cannabidiol (CBD) are attracting attention, including as a potential treatment in neurodevelopmental disorders such as autism spectrum disorder (ASD). However, the neural action of CBD, and its relevance to ASD, remains unclear. We and others have previously shown that response to drug challenge can be measured using functional magnetic resonance imaging (fMRI), but that pharmacological responsivity is atypical in ASD. Aims: We hypothesized that there would be a (different) fMRI response to CBD in ASD. Methods: To test this, task-free fMRI was acquired in 34 healthy men (half with ASD) following oral administration of 600 mg CBD or matched placebo (random order; double-blind administration). The ‘fractional amplitude of low-frequency fluctuations’ (fALFF) was measured across the whole brain, and, where CBD significantly altered fALFF, we tested if functional connectivity (FC) of those regions was also affected by CBD. Results: CBD significantly increased fALFF in the cerebellar vermis and the right fusiform gyrus. However, post-hoc within-group analyses revealed that this effect was primarily driven by the ASD group, with no significant change in controls. Within the ASD group only, CBD also significantly altered vermal FC with several of its subcortical (striatal) and cortical targets, but did not affect fusiform FC with other regions in either group. Conclusion: Our results suggest that, especially in ASD, CBD alters regional fALFF and FC in/between regions consistently implicated in ASD. Future studies should examine if this affects the complex behaviours these regions modulate.

Soft Palate Reflex: Technical Requirements and First Results

1992 ◽  
Vol 29 (4) ◽  
pp. 340-345 ◽  
Author(s):  
Godber S. Godbersen ◽  
Johannes Schneider-Littfeld ◽  
Jochen A. Werner ◽  
Sönke Wolters ◽  
Axel Pellner
Keyword(s):  
Soft Palate ◽  
Healthy Subjects ◽  
Processing System ◽  
Data Processing System ◽  
Response Latencies ◽  
Technical Requirements ◽  
First Results ◽  
The Individual ◽  
Electromyographic Signals ◽  
Stimulation Of

The present study describes technical prerequisites for soft palate reflex measurements and first results. Reflex measurements can be done using standard electromyographic methods. The data-processing system that records and processes the electromyographic signals was activated when the soft palate was stimulated by a newly developed device. The first results of objective soft palate reflex measurements in 15 healthy subjects show that the musculus levator veli palatini reacts to a mechanical stimulation of the soft palate with a contraction that can be measured electromyographicslly. The response latencies were constant in the individual subjects. In 12 subjects a minimum of 30 ms and a maximum of 61 ms was recorded. In one healthy subject, the reflex was activated only after 167 ms. No reflex could be evoked in two subjects. The stimulus was always supraliminal. Reaction time was longer following surface anesthesia of the oral mucosa.

scholarly journals Needle-Free Electroacupuncture for Postoperative Pain Management

2011 ◽  
Vol 2011 ◽  
pp. 1-7 ◽  
Author(s):  
Daniel Lee ◽  
Hong Xu ◽  
Jaung-Geng Lin ◽  
Kerry Watson ◽  
Rick Sai Chuen Wu ◽  
...  
Keyword(s):  
Postoperative Pain ◽  
Low Frequency ◽  
Postoperative Pain Management ◽  
Control Group ◽  
High Frequency Stimulation ◽  
Double Blind ◽  
Group 4 ◽  
Frequency Stimulation ◽  
Post Hoc ◽  
Stimulation Group

This study examined the effects of needle-free electroacupuncture, at ST36 on postoperative pain following hysterectomy. Based on a double-blind, sham, and different intervention controlled clinical experimental design, 47 women were randomly allocated to four different groups. Except for those in the control group (Group 1,n=13), a course of treatment was given of either sham (Group 2,n=12), high-frequency stimulation (Group 3,n=12), or low-frequency stimulation (Group 4,n=10). All groups were assessed during the postoperative period for 24 hours. The Visual Analogue Scale was used to determine the amount of perceived pain felt by each subject. Differences were found between the means postoperatively at three, four, eight, 16, and 24 hours. Post hoc comparison tests indicated that Group 4 was significantly different from Groups 1, 2, and 3 at 24 hours. A one-way ANOVA analysis for total patient-controlled analgesia demand and doses indicated significant differences between the groupsF(3,42)=3.59,P<.05. Post hoc analysis confirmed the differences between Groups 1 (M=84.54) and 4 (M=41.60). Treatment outcomes of this therapy showed a positive effect for the management of postoperative pain.

Impact of Low-Frequency Pulsed Magnetic Fields on Defensin and CRP Concentrations in Patients with Painful Diabetic Polyneuropathy and in Healthy Subjects

2010 ◽  
Vol 29 (1-12) ◽  
pp. 19-25 ◽  
Author(s):  
Marta Patrycja Wróbel ◽  
Aleksandra Szymborska-Kajanek ◽  
Joanna Katarzyna Strzelczyk ◽  
Dariusz Karasek ◽  
Hend Anna Rawwash ◽  
...  
Keyword(s):  
Magnetic Fields ◽  
Healthy Subjects ◽  
Low Frequency ◽  
Diabetic Polyneuropathy ◽  
Pulsed Magnetic Fields
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