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PubMed1997

Autonomic evaluation by means of standard tests and power spectral analysis in multiple sclerosis.

Standard autonomic tests [heart rate response to deep breathing (HRDB), change in systolic blood pressure due to tilt], and spectral analysis of heart rate (HR), arterial blood pressure (ABP), and the associated transfer function analysis (gains and phases) were performed in 20 patients with multiple sclerosis to determine their diagnostic value. Transfer function analysis suggested impairment of baroreflex function in 7 patients and an alteration of cardiorespiratory coupling on a brain stem level in 4 patients. In addition, sympathetic vasomotor outflow was reduced in 2 patients (spectral ABP measures in the mid frequency band) and a decrease of vagal outflow was suggested by abnormal respiratory HR parameters in another 2 patients. An abnormal HRDB was present in 5 patients and was probably due to a central alteration (cardiorespiratory coupling) in 2 patients and due to diminished respiratory effort in 1 patient. Spectral analysis of both HR and ABP oscillations and their transfer function may considerably improve the pathophysiological interpretation of cardiovascular autonomic dysfunction in patients with central nervous system disease.

Adult↗
PubMed1993

An estimate of fetal autonomic state by spectral analysis of fetal heart rate fluctuations.

The assessment of the functional state of the autonomic nervous system (ANS) in real time, by means of spectral analysis of fetal heart rate variability, may serve to improve the diagnosis of pathologic conditions of importance to the perinatologist. The combination of two approaches, namely an efficient method for detecting fetal ECG from the abdominal maternal signal, followed by spectral analysis of heart rate variability, is tested as a new noninvasive tool to assess fetal viability in real time. This study demonstrates a pattern of ANS development via the spectral contents of heart rate variability. It is shown that during "quiet state," the "young" fetuses (gestational age = 23.5 +/- 1 wk) present twice as much power of heart rate fluctuations at all frequencies from 0.2 to 1.0 Hz as "mature" fetuses (gestational age = 39.75 +/- 1.5 wk). This finding is coherent with the evolution of a stable and mature ANS activity. At frequencies below 0.1 Hz, a 1/f alpha power law relationship (alpha = 0.85, r2 > 0.9) between spectral density and frequency is displayed in the two age groups. A respiratory peak has been observed in some of the short (64-s) traces we analyzed. However, no respiratory peak was ever observed in a long (256-s) trace, due to the episodic nature of the fetal breathing and immaturity of the ANS.

Algorithms↗
PubMed2001

Detection of a biorhythm of human fetal autonomic nervous activity by a power spectral analysis.

OBJECTIVE: This study describes a 24-hour assay of autonomic nervous system activity in human fetuses with the use of a power spectral analysis of heartbeat intervals. STUDY DESIGN: The study included 6 normal fetuses and 11 growth-restricted fetuses, 3 of which were hypoxemic. Fetal heartbeats were continuously recorded for 24 hours, and a power spectral analysis was performed on the beat interval data. A low frequency domain of beat intervals was identified (0.025-0.125 cycles/beat) and evaluated at regular intervals over the 24-hour period. The cosinor method was used to detect rhythmic fluctuations in the resulting low frequency areas. The same procedures were also performed with the mothers of the fetuses. RESULTS: We observed 2 diurnal rhythms of heartbeat activity (1 with a 12-hour period and another with a 24-hour period) in the normal and growth-restricted fetuses without hypoxemia. In contrast, these rhythms were not observed in the hypoxemic fetuses. In the mothers, only the 24-hour rhythm was observed. CONCLUSION: The 12-hour cycle of autonomic nervous activity is present in normal fetuses.

Autonomic Nervous System↗
PubMedDate not supplied

Duplex-Doppler spectral analysis in the physiopathology of the temporomandibular joint.

We introduce a new method of analysis of the normal and abnormal behavior of the TMJ, using a duplex-doppler spectral analysis. The method consists in monitoring the joint movement by means of a study of the Fourier transformed signals, which give information on the velocity distribution of the condylo-meniscal complex during the opening and closing phases of the jaw. Using repeated sampling over short time intervals we get a detailed description of the motion which allows to discriminate the normal and abnormal action of the condylomeniscal complex. We are able to identify various physiopathological conditions, among which opening and/or closing clicks, complex locking conditions and anomalies related to an asymmetrical behavior during the operation cycle. Duplex-doppler spectral analysis is correlated to a clinical examination in order to define various classes of anomalies.

Cartilage, Articular↗
PubMed1986

Power spectral analysis of electroencephalographic activity in kindled rats.

Power spectral analysis of the resting EEG activity of amygdala kindled rats revealed a decrease of power in the 1- to 3-Hz band and an increase in the 4- to 6-Hz band compared with 3-Hz-stimulated and operated control animals. This effect was observed only in the stimulated but not the contralateral amygdala. The alteration in power seen shortly after kindling was still evident after a 1-month stimulation-free period.

Amygdala↗
PubMed1990

Heart rate spectral analysis for assessing autonomic regulation in diabetic patients.

Spectral analysis of the R-R variability signal has been used for assessing the autonomic regulation of heart rate in control subjects and in diabetic patients affected by autonomic neuropathy. Modifications of the parasympathetic-sympathetic balance following postural changes, as observed in normal subjects, were not significant in autonomic patients. In addition, the overall reduction of power occurring in diabetics at all frequencies indicates the impairment of both autonomic components.

Diabetes Mellitus↗
PubMedDate not supplied

Spectral analysis of electroencephalogram during perceptual-motor learning.

Spectral analysis of the electroencephalogram was utilized to determine attention demands during learning of a perceptual motor task. Fifteen subjects participated in the task which consisted of 15 trials of the mirror star learning task. EEG was monitored bilaterally from the occipital and parietal lobes during each trial and analyzed for intensity and mean frequency components within five different bandwidths. All subjects rapidly improved performance in terms of both time and error reduction although the former measure appeared to be a better fit of the supradiagonal form of matrix typically found for this type of learning. Mean alpha frequency increased slightly during the task while delta frequency decreased.

Adolescent↗
PubMed1991

Variation in power spectral analysis of the EEG with gestational age.

Power spectral analysis (PSA) of the EEG was studied in healthy term and preterm neonates to establish the normal range with gestational age. Sixty healthy newborn infants from 26 to 41 weeks' gestation had PSA performed at 3 days of age. Five main frequency bands were studied: delta 1 (1 Hz or less), delta 2 (2-3 Hz), theta, alpha, and beta. A significant correlation was shown between absolute power in delta 1 and delta 2 with gestational age. Relative power of each frequency band, calculated as a percentage of the total power in each channel, also correlated with gestational age. A significant quadratic relationship between absolute power in the beta range and gestational age is described for the first time.

Electroencephalography↗
PubMed1984

Detection of carotid occlusive disease by pulsed Doppler spectral analysis.

In this study a new pulsed Doppler spectral analysis system was used for the evaluation of extracranial carotid disease. When compared to the arteriography findings in 224 carotid arteries, the Doppler examination correctly detected all stenoses greater than 25%, all occlusions, all normal vessels, and 43% of stenosis causing a diameter reduction of less than 25%.

Carotid Artery Diseases↗
PubMed1983

Spectral analysis of tremorine and cold tremor electromyograms in animal species of different size.

In 14 mice (36.2 +/- 5.4 g), 17 rats (425 +/- 46.4 g), and 11 rabbits (3,200 +/- 340 g) a comparative electromyographic analysis of tremorine tremor and cold tremor was performed in gastrocnemius and tibialis anterior muscles using spectral analysis. The mean frequency of cold tremor decreased with increasing body weight (mice: 40.2 +/- 4.5 Hz; rats: 31.3 +/- 4.9 Hz; rabbits: 16.4 +/- 3.2 Hz). With tremorine tremor no such allometric correlation was found for tremor frequency and body weight (mice: 17.7 +/- 3.6 Hz; rats: 19.6 +/- 5.1 Hz; rabbits: 15.9 +/- 2.1 Hz). Cross spectral analysis revealed that during cold tremor the flexor muscle (tibialis anterior) and the extensor muscle (gastrocnemius) of rabbits are activated alternately. The mean phase shift between the activation of flexor and extensor muscle was -155.5 degrees. Stronger activation was observed in the flexor muscle. Tremorine tremor was characterized by synchronous activation of flexor and extensor muscles with a mean phase angle of 3.0 degrees and a predominance of the extensor muscle. The results suggest that the nervous mechanisms for the generation of tremorine tremor and cold tremor are different.

Animals↗
PubMed1992

The spectral analysis of hypnotic performance with respect to "absorption".

In factor analyses of the hypnosis scales, the essential result is that the items form a continuous, 2-dimensional fan-shaped pattern. This continuum is referred to as the "spectrum of hypnotic performance." "Special analysis" is introduced as an exploratory procedure which makes use of this notion of continuum or spectrum. Spectral analysis consists of a graphical display of the level of latent correlation between a variable and individual hypnotic performances when the latter are arranged according to their position in the spectrum. The spectral analysis of hypnotic performance with respect to absorption is illustrated using data from a sample of 160 Ss. The results indicate that absorption is more strongly related to difficult hypnotic performances than to easy ones. In particular, illustrative item characteristic curves are presented to show that although easy hypnotic performances do not require the processes tapped by individual differences in absorption, a certain level of absorption is necessary to pass difficult hypnotic items. In addition, a high level of absorption may be sufficient in and of itself for difficult hypnotic performances. These results are discussed in light of some speculations by Shor, M. T. Orne, and O'Connell (1962) and Tellegen (1978/1979) concerning the differential contribution of ability components to performance on difficult hypnotic suggestions. The results are also related to a variety of work in social psychological models of hypnotic performance.

Factor Analysis, Statistical↗
PubMed1999

Power spectral analysis of heart rate variability for assessment of diurnal variation of autonomic nervous activity in miniature swine.

BACKGROUND AND PURPOSES: The purpose of the study was to document diurnal variation of autonomic nervous functions by use of power spectral analysis of heart rate (HR) variability. METHODS: To clarify characteristics of power spectral analysis of HR variability, electrocardiogram (ECG), blood pressure (BP), and respiratory (Resp) waveform simultaneously were recorded. RESULTS: Two major spectral components were examined at low (LF)- and high (HF)-frequency bands for HR variability. Coherence between HR and Resp variabilities and HR and BP variabilities was maximal at approximately 0.14 and 0.03 Hz, respectively. On the basis of these data, two frequency bands of interest--LF (0.01 to 0.07 Hz) and HF (0.07 to 1.0 Hz)--were defined. Autonomic blockade studies indicated that the parasympathetic system mediated the HF and LF components, whereas the sympathetic system mediated only the LF component; HR had a diurnal pattern. The LF and HF bands in the dark phase tended to be higher than those in the light phase. The LF-to-HF ratio had a diurnal pattern similar to that of the HR. CONCLUSION: Parasympathetic nervous activity in miniature swine may be predominant in the dark phase. The characteristics of power spectra and diurnal variations of autonomic nervous functions are almost the same as those of humans. Therefore, miniature swine may be a useful animal model for future biobehavioral and pharmacotoxicologic studies.

Animals↗
PubMed2001

Capsaicin increases modulation of sympathetic nerve activity in rats: measurement using power spectral analysis of heart rate fluctuations.

We assessed the sympatho-vagal activities of the heart after administration of capsaicin by measuring the power spectral analysis in rats. There were major two frequency components of heart rate variability, which we defined as high (1.0 Hz <, HF) and low (LF, < 1.0 Hz) frequency components. Vagal blockade by atropine abolished the high frequency component, and lowered the amplitude of the low frequency component. On the other hand, under conditions of sympathetic blockade by propranolol, the low frequency component was reduced. Combined vagal and sympathetic blockade abolished all heart rate fluctuations. We analyzed the low and high frequency components by integrating the spectrum for the respective band width. The rats administered capsaicin had a higher heart rate and sympathetic nervous system index (LF/HF) than the control group of rats. These results suggest that power spectral analysis is an effective and noninvasive method for detecting subtle changes in autonomic activity in response to the intake of foods or drugs.

Animals↗
PubMedDate not supplied

Carotid ultrasonic arteriography combined with real time spectral analysis: a comparison with angiography.

In a one year period, 400 patients were examined by carotid ultrasonic arteriography combined with real time sound spectral analysis. Contrast arteriography was performed on 112 patients. The noninvasive examinations and contrast arteriograms of these patients were reviewed by two independent observers, who were unaware of the findings of the other diagnostic modality. There were 190 vessels available for comparison. The internal carotid artery was classified as normal, less than 50% stenosis, greater than or equal to 50% stenosis, or occluded. The specificity of these non-invasive tests was 79%. The sensitivity in correctly identifying stenoses as less than 50% or greater than or equal to 50 was 85% and 91% respectively. The sensitivity in identifying occluded vessels was 90%. The positive and negative predictive values were 87% and 92% respectively. Noninvasive evaluation correctly identified six lesions misdiagnosed by arteriography. We found pulsed Doppler arteriography combined with real time spectral analysis to be an accurate, direct, noninvasive method of assessing the extracranial carotid arteries.

Arterial Occlusive Diseases↗
PubMed1999

Perception of complex tones and its analogy to echo spectral analysis in the bat, Megaderma lyra.

The gleaning bat Megaderma lyra emits broadband echolocation sounds consisting of multiple frequency components. The present study investigates into which perceptual qualities the spectral characteristics of echoes may be translated in the auditory system of M. lyra. Three bats were trained in a 2-AFC behavioral experiment to classify nine complex tones, which spectrally resembled M. lyra's sonar calls, into two perceptual categories. Then the bats' spontaneous responses to unknown complex tones were recorded. The results show that the animals based their classifications of the complex tones on a sound quality which was mediated by their broadband frequency spectra. The bats used the training stimuli as spectral templates and classified the test stimuli according to their broadband spectral similarity with the learned patterns. Assuming that passive hearing and echo processing are governed by similar perceptual qualities and subject to similar limitations, the perceptual mode which was used by the bats to compare the multicomponent spectral patterns in the reported experiments could serve as a powerful tool for the spectral analysis of M. lyra's multicomponent echoes. The analogy between the perception of complex tones and echo spectral analysis in M. lyra is theoretically elaborated in the "formant-mode" model.

Animals↗
PubMed2005

Spectral analysis of sleep EEG in patients with restless legs syndrome.

OBJECTIVE: Conventional analyses of sleep EEG recordings according to standard criteria indicate severe sleep disturbances in patients with restless legs syndrome (RLS). Spectral analysis of sleep EEG may be a sensitive tool to detect functional alterations of sleep mechanisms beyond the visual scoring of polysomnographic records. We analysed sleep EEG spectral power differences between RLS patients and healthy subjects. Furthermore, we studied the relationship of sleep EEG spectral power to the occurrence of periodic leg movements in sleep (PLMS) and arousal events. METHODS: Sleep EEGs from 20 patients with idiopathic RLS and of 20 age and sex matched healthy subjects were investigated. The spectral analysis was carried out on the same 30s epochs for which sleep stages had been determined. As a first step, whole-night spectral power excluding epochs with an arousal or with a PLMS was compared separately for REM and NREM sleep between RLS and healthy subjects. In a second step, we evaluated the spectral effects of PLMS, PLMS with associated arousals and isolated arousals relative to epochs of sleep without such events in both groups. In this part of the analysis, we only included the epochs of sleep stage 2 (the main and most stable non-REM sleep stage) and of REM sleep. RESULTS: Spectral power of all sleep epochs (excluding arousals and PLMS) did not differ between patients with RLS and healthy subjects. As expected, arousals and PLMS-associated arousals resulted in a significant increase in higher-frequency activity (alpha, beta1, beta2 and gamma bands) in both groups. Spectral power in epochs with PLMS alone did not significantly differ from spectral power in epochs without PLMS and without arousal in any of the groups. CONCLUSIONS: We found no evidence for an altered cortical activity in sleep stage 2 and REM sleep epochs in RLS patients compared to that in healthy controls if epochs with arousals were not considered. Furthermore, while PLMS associated with an arousal have a high impact on EEG spectra, the effect of a PLMS without arousal seems to be minor and transient. SIGNIFICANCE: Our data suggest that RLS related symptoms may intermittently disrupt sleep but do not appear to involve a persistent disturbance of the basic sleep generating patterns.

Adult↗
PubMed1986

Spectral analysis with digital presentation of C-W Doppler signals in the evaluation of carotid stenosis.

Using a continuous-wave ultrasound Doppler system with spectral analysis (FFT) and digital processing and presentation, the Doppler shift characteristics of the carotid arteries were studied in 40 healthy subjects (20 men and 20 women; average age 69 years). The reference values, thus obtained, were applied to the analysis of sonograms from 46 carotid arteries, which were also studied angiographically. Stenoses which reduced the diameter of the internal carotid artery by more than 30% could be identified with a sensitivity of 97% and a specificity of 100%. The results extend previous experience that spectral analysis improves the usefulness of the ultrasound Doppler system in the evaluation of carotid artery disease. The addition of digital processing and presentation of the Doppler shift characteristics increases the diagnostic precision and provides a permanent record. The importance of well-trained sonographers and adequate reference values is emphasized.

Aged↗
PubMed1991

Modulation of the dose-dependent effects of atropine by low-dose pyridostigmine: quantification by spectral analysis of heart rate fluctuations in healthy human beings.

The interaction between a low-dose cholinesterase inhibitor, pyridostigmine (PYR), and atropine was investigated by spectral analysis of heart rate fluctuations in eight healthy humans. Each subject was given increasing boluses of IV atropine during treatment with PYR (30 mg.3/day) or placebo. PYR attenuated the bimodal dose-dependent changes in the respiratory peak (which respresents the parasympathetic control) in response to atropine. We suggest that spectral analysis can be used for quantifying the complex dose-dependent cholinergic agonist-antagonist interactions, and may help to disclose an asymptomatic low-dose intoxication with acetylcholinesterase inhibitors.

Adult↗