共查询到20条相似文献,搜索用时 15 毫秒
1.
Nagy E Feher-Kiss A Barnai M Domján-Preszner A Angyan L Horvath G 《European journal of applied physiology》2007,100(1):97-104
The changes in postural control in elderly people after an 8-week training course were characterized. Static postural stability
was measured during standing on a single force platform first with the eyes open and then with the eyes closed. Body sway
was analysed on a force plate in groups of elderly and of young subjects. Half of the elderly subjects then took part in the
training course. The posturographic measurements were repeated after the course. The sway in anteroposterior (AP) and mediolateral
(ML) directions was subjected to spectral analysis. The frequency spectrum of the platform oscillations was calculated by
fast Fourier transformation in the intervals 0.1–0.3, 0.3–1 and 1–3 Hz. It was found that the sway path was longer and the
frequency power was higher in the elderly group. The training caused a significant improvement in functional performance,
but a significantly longer sway path was observed after the training in the ML direction. The frequency analysis revealed
a significantly higher power after 8 weeks without visual control in the ML direction in the training group in the low and
the middle frequency bands. The results suggest that the participants’ balance confidence and the control of ML balance improved
in response to the training. The higher ML frequency power exhibited after the training may be indicative of a better balance
performance. Thus, the increase in the sway path in this age group did not mean a further impairment of the postural control. 相似文献
2.
Summary Postural sway behaviour was investigated in 30 young subjects (15 male and 15 female) during 60 s of erect standing, under various combinations of auditory and visual input. Sway was assessed using a standard biomechanical measuring platform, the output of which led directly to an online computer from which the following parameters were determined: mean lateral and antero-posterior sway, velocity and radius of sway, length of the sway path and area within the sway profile. A marked difference in sway behaviour between the sexes was observed, with women showing increased magnitudes of some sway parameters. Postural sway was significantly increased in conditions without visual feedback. The presence of an auditory field tends to have a destabilising influence on sway behaviour, with both the direction of the sound source and the type of auditory input being important variables. Nevertheless there appears to be no interaction between the visual and the auditory environment in the control of posture. 相似文献
3.
Sparto PJ Redfern MS Jasko JG Casselbrant ML Mandel EM Furman JM 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》2006,168(4):505-516
Young children rely heavily on vision for postural control during the transition to walking. Although by 10 years of age,
children have automatic postural responses similar to adults, it is not clear when the integration of sensory inputs becomes
fully developed. The purpose of this study was to examine this transition in the sensory integration process in children aged
7–12 years. Healthy children and adults stood on a fixed or sway-referenced support surface while viewing full-field optic
flow scenes that moved sinusoidally (0.1 and 0.25 Hz) in an anterior–posterior direction. Center of pressure was recorded,
and measures of sway amplitude and phase were calculated at each stimulus frequency. Children and adults had significant postural
responses during approximately two-thirds of the trials. In adults, there was a 90% decrease in sway on the fixed surface
compared with the sway-referenced surface, but only a 50% decrease in children. The phase between the optic flow stimulus
and postural response in children led that of adults by 52° at 0.1 Hz and by 15° at 0.25 Hz. Adults and children aged 7–12 years
have similar ability to use dynamic visual cues for postural control. However, 7–12-year-old children do not utilize somatosensory
cues to stabilize posture to the same extent as adults when visual and somatosensory cues are conflicting. 相似文献
4.
Boonstra TW Roerdink M Daffertshofer A van Vugt B van Werven G Beek PJ 《Journal of neurophysiology》2008,100(4):2158-2164
The effects of low doses of alcohol on neural synchronization in muscular activity were investigated in ten participants during quiet standing with eyes open or closed. We focused on changes in common input to bilateral motor unit pools as evident in surface electromyographic (EMG) recordings of lower leg extensor and flexor muscles. The extensor muscles exhibited bilateral synchronization in two distinct frequency bands (i.e., 0–5 and 10–15 Hz), whereas synchronization between flexor muscles was minimal. As expected, alcohol ingestion affected postural sway, yielding increased sway at higher blood-alcohol levels. Whereas vision affected bilateral synchronization only at 0–5 Hz, alcohol ingestion resulted in a progressive decrease of synchronization at 10–15 Hz between the EMG activities of the extensor muscles. The decrease in common bilateral input is most likely related to reduced reticulospinal activity with alcohol ingestion. 相似文献
5.
A. E. Pavlik J. T. Inglis M. Lauk L. Oddsson J. J. Collins 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1999,124(3):273-280
Galvanic vestibular stimulation serves to modulate the continuous firing level of the peripheral vestibular afferents. It
has been shown that the application of sinusoidally varying, bipolar galvanic currents to the vestibular system can lead to
sinusoidally varying postural sway. Our objective was to test the hypothesis that stochastic galvanic vestibular stimulation
can lead to coherent stochastic postural sway. Bipolar binaural stochastic galvanic vestibular stimulation was applied to
nine healthy young subjects. Three different stochastic vestibular stimulation signals, each with a different frequency content
(0–1 Hz, 1–2 Hz, and 0–2 Hz), were used. The stimulation level (range 0.4–1.5 mA, peak to peak) was determined on an individual
basis. Twenty 60-s trials were conducted on each subject – 15 stimulation trials (5 trials with each stimulation signal) and
5 control (no stimulation) trials. During the trials, subjects stood in a relaxed, upright position with their head facing
forward. Postural sway was evaluated by using a force platform to measure the displacements of the center of pressure (COP)
under each subject’s feet. Cross-spectral measures were used to quantify the relationship between the applied stimulus and
the resulting COP time series. We found significant coherency between the stochastic vestibular stimulation signal and the
resulting mediolateral COP time series in the majority of trials in 8 of the 9 subjects tested. The coherency results for
each stimulation signal were reproducible from trial to trial, and the highest degree of coherency was found for the 1- to
2-Hz stochastic vestibular stimulation signal. In general, for the nine subjects tested, we did not find consistent significant
coherency between the stochastic vestibular stimulation signals and the anteroposterior COP time series. This work demonstrates
that, in subjects who are facing forward, bipolar binaural stochastic galvanic stimulation of the vestibular system leads
to coherent stochastic mediolateral postural sway, but it does not lead to coherent stochastic anteroposterior postural sway.
Our finding that the coherency was highest for the 1- to 2-Hz stochastic vestibular stimulation signal may be due to the intrinsic
dynamics of the quasi-static postural control system. In particular, it may result from the effects of the vestibular stimulus
simply being superimposed upon the quiet-standing COP displacements. By utilizing stochastic stimulation signals, we ensured
that the subjects could not predict a change in the vestibular stimulus. Thus, our findings indicate that subjects can act
as ”responders” to galvanic vestibular stimulation.
Received: 13 March 1998 / Accepted: 8 October 1998 相似文献
6.
Power spectra of short-term (less than 1 sec) electrical responses to conditioned stimuli were studied over the frequency
range 1–225 Hz in dogs during food-related operant conditioning. These spectra demonstrated regional characteristics in terms
of energy levels and frequency composition. Responses were more marked in the visual and parietal areas of the left hemisphere.
Power in responses to a differential stimulus were significantly lower than with responses to positive stimuli, mainly because
of the high-frequency range (80–225 Hz); energy levels in these two situations were similar during prestimulus intervals.
The frequency composition of responses was defined by a series of discrete frequencies in the gamma (30–80 Hz) and high-frequency
ranges.
__________
Translated from Zhurnal Vysshei Nervnoi Deyatel’nosti imeni I. P. Pavlova, Vol. 55, No. 5, pp. 658–670, September–October,
2005. 相似文献
7.
Saffer M Kiemel T Jeka J 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》2008,185(2):215-226
Studies of muscle activation during perturbed standing have demonstrated that the typical patterns of coordination (“ankle
strategy” and “hip strategy”) are controlled through multiple muscles activated in a distal-to-proximal or proximal-to-distal
temporal pattern. In contrast, quiet stance is thought to be maintained primarily through the ankle musculature. Recently,
spectral analysis of inter-segment body motion revealed the coexistence of both ankle and hip patterns of coordination during
quiet stance, with the predominating pattern dependent on the frequency of body sway. Here we use frequency domain techniques
to determine if these patterns are associated with the same muscular patterns as observed during perturbed stance. Six of
the seven muscles measured showed a linear relationship to the sway of at least one body segment, all being leg muscles. Muscle–segment
phases were consistent with that required to resist gravity at low frequencies, with increasing phase lag as frequency increased.
Visual information had effects only at frequencies below 0.5 Hz, where the shift from in-phase to anti-phase trunk–leg co-phase
was observed. These results indicate that co-existence of the ankle and hip pattern during quiet stance involves only leg
musculature. Anti-phase movement of the trunk relative to the legs at higher frequencies arises from indirect biomechanical
control from posterior leg muscles. 相似文献
8.
Stefano Corna Jessica Tarantola Antonio Nardone Andrea Giordano M. Schieppati 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1999,124(3):331-341
We describe the characteristics of displacement of the head and hip in normal young subjects standing on a moving platform
undergoing continuous sinusoidal horizontal translation in the antero-posterior direction, at frequencies ranging from 0.1–1
Hz. The head, hip and malleolus were marked by light-emitting diodes (LEDs), and the displacement of each LED was quantified
by (1) the measure of the shift during each cycle of translation, (2) the standard deviation (SD) of the path travelled during
the whole trial, (3) the power spectrum (PS) of the signal and (4) the cross-correlation (CC) between pairs of LED signals.
At each frequency of translation, with eyes open (EO), the displacement of head was smaller than that of hip, and the displacement
of hip was smaller than that of malleolus. With eyes closed (EC), this order was reversed. The peak value of the CC functions
of the pairs malleolus/head, malleolus/hip and hip/head decreased by passing from low to high frequency of translation, under
both visual conditions, and decreased more for the pair malleolus/head than malleolus/hip. The lags between body segment displacements
ranged between 30 ms and 150 ms, on average, the former segment of each pair preceding the latter. The fast Fourier transformation
of hip and head displacement showed a power spectrum peak at the frequency imposed by the platform translation. The peak was
larger with EC than EO. With EC, another peak appeared at 0.2 Hz, possibly corresponding to the respiratory frequency. We
conclude that, when vision was allowed, subjects behaved as a non-rigid, non-inverted pendulum, and stabilised head in space.
When vision was denied, head oscillated more than the platform, especially at low translation frequencies. Therefore, the
strategy of balance control shifted from a pendulum to an inverted-pendulum behaviour, passing from active head-and-trunk
control to maximal body compliance to the perturbation.
Received: 20 April 1998 / Accepted: 8 November 1998 相似文献
9.
Stephenson JL Christou EA Maluf KS 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》2011,208(2):203-215
This study examined discharge rate modulation at respiratory (0–0.5 Hz) and beta (16–32 Hz) frequencies in trapezius motor
units active during voluntary contractions and during periods of instructed rest under conditions of low and high psychosocial
stress. In separate sessions, single motor unit activity was recorded from the trapezius muscle of healthy women during low-intensity
voluntary contractions and during periods of instructed muscle rest that followed voluntary contractions. The level of psychosocial
stress during periods of instructed muscle rest was manipulated using a verbal math task combined with social evaluative threat
which increased perceived anxiety, heart rate, and blood pressure (P ≤ 0.002). Discharge rate modulation was quantified by the mean power of motor unit discharge rate profiles within frequency
bands of interest. Under low stress conditions, motor units active during instructed rest had greater power at 0–0.5 Hz (P = 0.002) and less power at 16–32 Hz (P = 0.009) compared to those active during voluntary contraction. Exposure to the stressor increased the amount of motor unit
activity during instructed rest (P = 0.021) but did not alter the power of discharge rate modulation at 0–0.5 Hz (P = 0.391) or 16–32 Hz (P = 0.089). These results indicate that sustained motor unit activity during periods of instructed muscle rest has a lesser
contribution from inputs at beta frequencies and a greater contribution from inputs at respiratory frequencies than present
during low-intensity voluntary contractions. Furthermore, increases in motor unit activity when exposed to stressors during
periods of instructed rest are not caused by changes in inputs at respiratory or beta frequencies. 相似文献
10.
Power spectra over the frequency range 1–225 Hz in short-term (less than 1 sec) EEG reactions arising in different areas of
the cerebral cortex in response to presentation of differential signals were investigated in dogs during operant feeding behavior
in conditions of both adequate and erroneous responses. The energy levels of these reactions decreased several-fold as compared
with responses to positive signals, mainly because of frequencies in the high-frequency range (90–225 Hz), where power was
greater than not only the traditional range of 1–30 Hz, but also the gamma range of 30–80 Hz. The frequency composition of
EEG reactions in adequate responses was determined by a series of discrete frequency subgroups belonging predominantly to
the high-frequency band. In erroneous reactions, the discrete structure of the corresponding EEG reactions was lost.
__________
Translated from Zhurnal Vysshei Nervnoi Deyatel'nosti imeni I. P. Pavlova, Vol. 54, No. 5, pp. 673–687, September–October,
2004. 相似文献
11.
Mochizuki G Semmler JG Ivanova TD Garland SJ 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》2006,175(4):584-595
The maintenance of quiet stance requires the activation of muscles bilaterally. The soleus muscles in each leg share a common function in standing; that is, each muscle acts to control antero-posterior (AP) sway on its own side. We sought to determine the extent to which oscillations in motor unit discharge were related in motor unit pairs of the soleus muscles during postural and voluntary isometric tasks, both within and between legs. Subjects stood quietly for 5 min or performed a voluntary isometric plantarflexion contraction in a seated position. During the postural tasks, the excursions of AP sway between legs were highly correlated (ρ = 0.86 ± 0.06). The strength of common modulation of motor unit discharge rates was assessed using time- and frequency-domain analyses. The time-domain common drive analysis revealed that the strongest correlation in motor unit discharge modulation occurred in the postural task with unilateral pairs (ρ = 0.71 ± 0.13) being more strongly correlated than bilateral pairs (ρ = 0.50 ± 0.16). Common modulation of motor unit discharge was lowest for the voluntary tasks, with ρ = 0.38 ± 0.11 and 0.16 ± 0.08 for unilateral and bilateral pairs, respectively. Similarly, the frequency-domain coherence analysis demonstrated an identical ordering effect, with the largest maximum pooled coherence occurring during standing posture in unilateral (0.070 at 1.6 Hz) and bilateral (0.055 at 1.6 Hz) recordings, whereas minimal coherence was observed in the voluntary task in both unilateral and bilateral recordings within the 0–5 Hz range. These results indicate that in the soleus muscle, common modulation of motor unit discharge is greater during postural tasks than during voluntary isometric tasks and can be observed in both bilateral and unilateral motor unit pairs. Differences in the extent of co-modulation of motor unit discharge between tasks may be attributed to either differences in the descending control or differences in the proprioceptive input between postural and isometric tasks.This study was supported by an NSERC grant awarded to S.J. Garland and a CIHR doctoral fellowship awarded to G. Mochizuki. 相似文献
12.
Joey C. Eisenmann Peter T. Katzmarzyk Germain Thériault Thomas M. K. Song Robert M. Malina Claude Bouchard 《European journal of applied physiology》2000,81(1-2):40-46
The relationships between cardiac dimensions and physical activity and submaximal working capacity were examined in 198 boys
and 154 girls, aged 9–18 years, who were participants in the first phase of the Québec Family Study. The sample was divided
into three age groups, 9–12 years, 13–15 years, and 16–18 years. Indicators of physical activity included estimated daily
energy expenditure (EE) and time spent in moderate-to-vigorous physical activity (median metabolic equivalents of energy expenditure
above resting metabolic rate ≥4.8). Submaximal physical working capacity (PWC150) was determined using a submaximal exercise test on a Monark cycle ergometer. Echocardiographically determined dimensions
included posterior wall thickness, septal wall thickness, and left ventricular mass (LVM). The analyses were based on partial
correlation and analysis of covariance, controlling for age and body surface area. Relationships between EE/physical activity
variables and cardiac dimensions were low and, at best, moderate (r < 0.45). With subjects grouped into tertiles by indicators of physical activity, LVM was significantly different only among
16- to 18-year-old girls (157 g vs 134 g in the highest and lowest quartiles, respectively; P < 0.05). Correlations between cardiac dimensions and PWC150 were also low (r < 0.30), with few significant relationships. In general, cardiac dimensions were not related to habitual physical activity
and PWC150 in young subjects aged 9–18 years. However, significant correlations were positive, as expected. LVM may be related to submaximal
power output in boys since it accounts for 3% of the variance, after adjusting for age and BSA.
Received: 4 January 1999 / Accepted: 8 June 1999 相似文献
13.
V. N. Dumenko M. K. Kozlov N. S. Kurova E. A. Cheremushkin 《Neuroscience and behavioral physiology》2010,40(9):941-950
Interhemisphere cortical potential power ratios were studied in the 1–60 Hz band during the prestimulus period at the stages
of formation and testing of a cognitive set to a facial expression. Different topographies in the patterns of asymmetry in subjects with different levels of set expression were demonstrated. At the formation stage,
the group of subjects without actualization of the set (n = 11) showed significantly higher power levels at gamma frequencies (21–40 and 41–60 Hz) in the frontal areas of the right hemisphere and at frequencies at 2–7 and 8–13 Hz, also in the frontal areas, but in the left hemisphere. At the set testing stage, the main topographic asymmetry pattern in these subjects persisted. In subjects with
marked set actualization (n = 18), formation was characterized by a different topographical asymmetry pattern, with significantly higher power levels
at gamma frequencies seen in the posterior temporal and occipital areas of the left hemisphere at frequencies of 2–7, 8–13, and 14–20 Hz, also in the posterior areas, but in the right hemisphere. At the set testing stage, the phenomenon of interhemisphere asymmetry in the power of cortical potentials was
not seen. 相似文献
14.
Summary Postural sway behaviour was assessed, using a standard biomechanical measuring platform, in 30 young subjects (15 men, 15 women) during 60 s of erect standing in various combinations of visual input and moving auditory fields. The sway parameters investigated were mean lateral, antero-posterior, radius and velocity of sway, the area within the sway profile and the length of the sway path. The findings support the view that moving auditory fields have a destabilising influence on postural sway behaviour, and suggest that under the appropriate conditions postural sway can be driven by the auditory environment. 相似文献
15.
G. Schweigart T. Mergner G. Barnes 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1999,127(1):54-66
During natural behaviour in a visual environment, smooth pursuit eye movements (SP) usually override the vestibular-ocular
reflex (VOR) and the optokinetic reflex (OKR), which stem from head-in-space and scene-relative-to-eye motion, respectively.
We investigated the interaction of SP, VOR, and OKR, which is not fully understood to date. Eye movements were recorded in
two macaque monkeys while applying various combinations of smooth eye pursuit, vestibular and optokinetic stimuli (sinusoidal
horizontal rotations of visual target, chair and optokinetic pattern, respectively, at 0.025, 0.05, 0.1, 0.2, 0.4, and 0.8
Hz, corresponding to peak stimulus velocities of 1.25–40°/s for a standard stimulus of ±8°). Slow eye responses were analysed
in terms of gain and phase. During SP at mid-frequencies, the eyes were almost perfectly on target (gain 0.98 at 0.1 Hz),
independently of a concurrent vestibular or optokinetic stimulus. Pursuit gain at lower frequencies, although being almost
ideal (0.98 at 0.025 Hz with pursuit-only stimulation), became modified by the optokinetic input (gain increase above unity
when optokinetic stimulus had the same direction as target, decrease with opposite direction). At higher stimulus frequencies,
pursuit gain decreased (down to 0.69 at 0.8 Hz), and the pursuit response became modified by vestibular input (gain increase
during functionally synergistic combinations, decrease in antagonistic combinations).Thus, the pursuit system in monkey dominates
during SP-OKR-VOR interaction, but it does so effectively only in the mid-frequency range. The results can be described in
the form of a simple dynamic model in which it is assumed that the three systems interact by linear summation. In the model
SP and OKR dominate VOR in the low- to mid-frequency/velocity range, because they represent closed loop systems with high
internal gain values (>>1) at these frequencies/velocities, whereas the VOR represents an open loop system with about unity-gain
(up to very high frequencies). SP dominance over OKR is obtained by allowing an ’attentional/volitional’ mechanism to boost
SP gain and a predictive mechanism to improve its dynamics.
Received: 27 November 1998 / Accepted: 8 March 1999 相似文献
16.
Dakin CJ Inglis JT Blouin JS 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》2011,209(3):345-354
Electrical vestibular stimulation produces biphasic responses in muscles maintaining balance. The two components of these
muscle responses (termed the short latency and medium latency components) are believed to be independent and elicited by vestibular
stimuli of different frequencies. We tested these hypotheses by determining (a) if frequency-specific stimulation protocols
could evoke independently the short and medium latency responses and (b) whether these two components are triggered by distinct
brain regions with a fixed time delay, interacting around 10 Hz. First, subjects were provided 10–25 Hz, 0–10 Hz, and 0–25 Hz
vestibular stimuli to selectively modulate the short latency, medium latency, or both components of the response; and second,
they were provided twenty sinusoidal stimuli from 1 to 20 Hz with a 0–20 Hz control trial, designed to determine whether an
interaction between the short and medium latency responses occurs at a specific stimulation frequency. Both the 0–10 Hz and
10–25 Hz vestibular stimuli elicited multiphasic waveforms, suggesting the short and medium latency components were not modulated
independently by the frequency-specific stimuli. Sinusoidal vestibular stimuli evoked responses at the stimulated frequency
but no evidence of a reflex component interaction was observed. Instead, summation of the responses evoked by each of the
sinusoidal stimuli resembled the biphasic response to broad bandwidth stimuli. Due to the lack of interaction and linear contribution
of all stimulus frequencies to both the short and medium latency responses, the present results support the use of broad bandwidth
electrical vestibular signal for physiological or clinical testing. 相似文献
17.
Masanori Nagai Mitsuo Isida Junko Saitoh Yoshie Hirata Hatsumi Natori Maki Wada 《Neuroscience letters》2009
During pregnancy, the physical and mental states greatly change. We investigated the influences of pregnancy and anxiety on postural control in pregnant women (P) standing upright in the late trimester. An analysis of posturograms revealed that the area of body sway and length of antero-posterior body sway were greater in P than those in non-pregnant controls (NP). No difference was found in the medio-lateral body sway between P and NP. Fast Fourier transform analysis of body sway showed that the percentile power of the 1.0–10.0 Hz band in the medio-lateral axis was smaller in P than in NP irrespective of whether the eyes were open or closed. P were divided into a high (HA) and low (LA) anxiety group on the basis of state anxiety scored by Spielberger's State- and Trait-Anxiety Inventory. A positive correlation was identified between state anxiety and the area of body sway in HA standing with eyes open. This correlation was diminished when the eyes were closed. Body sway of over 1 Hz is generally stabilized by somatosensory input, therefore, the results show that body sway in the medio-lateral axis is stabilized in P by increasing the sensitivity to somatosensory cues. High anxiety during pregnancy destabilizes the standing posture when the eyes are open. The correlation between anxiety and body sway revealed by our previous studies in college students was also confirmed in P, suggesting that humans with high anxiety abstract visual cues differently from those with low anxiety. 相似文献
18.
Cohen B Martinelli GP Ogorodnikov D Xiang Y Raphan T Holstein GR Yakushin SB 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》2011,210(1):45-55
Blood pressure (BP) and heart rate (HR) were studied in isoflurane-anesthetized Long-Evans rats during sinusoidal galvanic
vestibular stimulation (sGVS) and sinusoidal oscillation in pitch to characterize vestibular influences on autonomic control
of BP and HR. sGVS was delivered binaurally via Ag/AgCl needle electrodes inserted over the mastoids at stimulus frequencies
0.008–0.4 Hz. Two processes affecting BP and HR were induced by sGVS: 1) a transient drop in BP (≈15–20 mmHg) and HR (≈3 beat*s−1), followed by a slow recovery over 1–6 min; and 2) inhibitory modulations in BP (≈4.5 mmHg/g) and HR (≈0.15 beats*s−1/g) twice in each stimulus cycle. The BP and HR modulations were approximately in-phase with each other and were best evoked
by low stimulus frequencies. A wavelet analysis indicated significant energies in BP and HR at scales related to twice and
four times the stimulus frequency bands. BP and HR were also modulated by oscillation in pitch at frequencies 0.025–0.5 Hz.
Sensitivities at 0.025 Hz were ≈4.5 mmHg/g (BP) and ≈0.17 beat*s−1/g (HR) for pitches of 20–90°. The tilt-induced BP and HR modulations were out-of-phase, but the frequencies at which responses
were elicited by tilt and sGVS were the same. The results show that the sGVS-induced responses, which likely originate in
the otolith organs, can exert a powerful inhibitory effect on both BP and HR at low frequencies. These responses have a striking
resemblance to human vasovagal responses. Thus, sGVS-activated rats can potentially serve as a useful experimental model of
the vasovagal response in humans. 相似文献
19.
To examine whether the postural balance is influenced by the degree of anxiety, body sway during orthostatic standing while gazing at a visual target was examined in college students. Students, physically and mentally healthy, were divided into two groups according to the degree of state anxiety; high anxiety group (HA) and low anxiety group (LA). A fast Fourier transform analysis of the postural sway in antero-posterior axis showed that frequency components of 0.02-0.21 Hz, reflecting vestibular inputs, were 16% greater and those of 2.02-10.0 Hz, reflecting somatosensory inputs, were 24% smaller in HA. These differences between HA and LA were abolished when the eyes were closed. It is concluded that the interactions of visual inputs with vestibular and somatosensory inputs are influenced by anxiety. 相似文献
20.
J. N. van der Meer A. C. Schouten L. J. Bour E. de Vlugt A. F. van Rootselaar F. C. T. van der Helm M. A. J. Tijssen 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》2010,202(3):681-691
In dystonia, both sensory malfunctioning and an abnormal intermuscular low-frequency drive of 3–7 Hz have been found, although
cause and effect are unknown. It is hypothesized that sensory processing is primarily disturbed and induces this drive. Accordingly,
experimenter-controlled sensory input should be able to influence the frequency of the drive. In six genetically confirmed
myoclonus-dystonia (MD) patients and six matched controls, the low-frequency drive was studied with intermuscular coherence
analysis. External perturbations were applied mechanically to the wrist joint in small frequency bands (0–4, 4–8 and 8–12 Hz;
‘angle protocol) and at single frequencies (1, 5, 7 and 9 Hz; ‘torque’ protocol). The low-frequency drive was found in the
neck muscles of 4 MD patients. In these patients, its frequency did not shift due to the perturbation. In the torque protocol,
the externally applied frequencies could be detected in all controls and in the two patients without the common drive. The
common low-frequency drive was not be affected by external perturbations in MD patients. Furthermore, the torque protocol
did not induce intermuscular coherences at the applied frequencies in these patients, as was the case in healthy controls
and in patients without the drive. This suggests that the dystonic 3–7 Hz drive is caused by a sensory-independent motor drive
and sensory malfunctioning in MD might rather be a consequence than a cause of dystonia. 相似文献