Power spectra of inspiratory nerve activity with lung inflations in cats

1988 ◽  
Vol 64 (4) ◽  
pp. 1709-1720 ◽  
Author(s):  
C. A. Richardson
Keyword(s):  
High Frequency ◽  
Power Spectra ◽  
High Peak ◽  
Spectral Peak ◽  
Respiratory Pattern ◽  
Inflation Pressure ◽  
High Frequency Peak ◽  
Lung Inflation ◽  
Consistent Manner ◽  
Inspiratory Activity

To investigate the effect of lung inflations on the high-frequency synchrony (70-122 Hz) observed in the inspiratory activity of respiratory motor nerves of decerebrate cats, I applied a step increase in lung inflation pressure at fixed delays into the inspiratory phase and computed power spectra of phrenic neurograms before and during inflation. In 25 decerebrate paralyzed cats the frequency of the high spectral peak was 92.3 +/- 11.1 Hz before and 105.3 +/- 12.1 Hz during the step in inflation pressure, shifting upward by 13.0 +/- 6.0 Hz. For 8 of the 25 cats, the recurrent laryngeal and phrenic neurograms were recorded simultaneously. The high spectral peak was present during inspiration in the recurrent laryngeal power spectra and coherent with the high peak in the phrenic power spectra. In response to lung inflation, the high peak disappeared from the power spectra of the recurrent laryngeal nerve as the inspiratory activity was inhibited; a shift upward in frequency was not detectable. Comparing inspiratory times (TI, based on the phrenic neurograms) for breaths with no lung inflations to those for breaths with lung inflations, I found that lung inflations early in inspiration caused a decrease in TI, lung inflations at intermediates times had no effect on TI, and lung inflations late in inspiration caused an increase in TI. Despite lung inflation decreasing, not affecting, or increasing inspiratory duration and amplitude of the phrenic neurogram, lung inflation always caused a shift upward in the high-frequency peak of the phrenic power density. The fact that lung inflation, a powerful respiratory stimulus, affected the frequency of the high peak in a consistent manner suggests that the high-frequency synchrony is an important and robust feature of the central respiratory pattern generator.

Nonrandom variability in respiratory cycle parameters of humans during stage 2 sleep

1990 ◽  
Vol 69 (2) ◽  
pp. 630-639 ◽  
Author(s):  
M. Modarreszadeh ◽  
E. N. Bruce ◽  
B. Gothe
Keyword(s):  
High Frequency ◽  
Minute Ventilation ◽  
Power Spectra ◽  
Low Frequency ◽  
Neural Mechanism ◽  
Normal Subjects ◽  
Feedback Loops ◽  
Low Frequency Oscillations ◽  
Stage 2 Sleep ◽  
Correlated Components

We analyzed breath-to-breath inspiratory time (TI), expiratory time (TE), inspiratory volume (VI), and minute ventilation (Vm) from 11 normal subjects during stage 2 sleep. The analysis consisted of 1) fitting first- and second-order autoregressive models (AR1 and AR2) and 2) obtaining the power spectra of the data by fast-Fourier transform. For the AR2 model, the only coefficients that were statistically different from zero were the average alpha 1 (a1) for TI, VI, and Vm (a1 = 0.19, 0.29, and 0.15, respectively). However, the power spectra of all parameters often exhibited peaks at low frequency (less than 0.2 cycles/breath) and/or at high frequency (greater than 0.2 cycles/breath), indicative of periodic oscillations. After accounting for the corrupting effects of added oscillations on the a1 estimates, we conclude that 1) breath-to-breath fluctuations of VI, and to a lesser extent TI and Vm, exhibit a first-order autoregressive structure such that fluctuations of each breath are positively correlated with those of immediately preceding breaths and 2) the correlated components of variability in TE are mostly due to discrete high- and/or low-frequency oscillations with no underlying autoregressive structure. We propose that the autoregressive structure of VI, TI, and Vm during spontaneous breathing in stage 2 sleep may reflect either a central neural mechanism or the effects of noise in respiratory chemical feedback loops; the presence of low-frequency oscillations, seen more often in Vm, suggests possible instability in the chemical feedback loops. Mechanisms of high-frequency periodicities, seen more often in TE, are unknown.

Spectral analysis of the EMG and diaphragmatic muscle fatigue during periodic breathing in infants

1985 ◽  
Vol 58 (3) ◽  
pp. 830-833 ◽  
Author(s):  
S. T. Nugent ◽  
J. P. Finley
Keyword(s):  
Spectral Analysis ◽  
Muscle Fatigue ◽  
Preterm Infants ◽  
High Frequency ◽  
Power Spectra ◽  
Low Frequency ◽  
Periodic Breathing ◽  
Full Term ◽  
Diaphragmatic Muscle ◽  
Normal Breathing

Periodic breathing occurs commonly in full-term and preterm infants. The mechanisms which switch breathing on and off within a cycle of periodic breathing are not certain. Since immature infants may experience diaphragmatic muscle fatigue, one potential switching mechanism is fatigue. Power spectra of the electromyogram, uncontaminated by the electrocardiograph artifact, were studied for evidence of diaphragmatic muscle fatigue during spontaneous periodic breathing in infants. A fall in the high-frequency (103–600 Hz) power and an increase in the low-frequency (23–47 Hz) power during periodic as compared with normal breathing would indicate fatigue. This effect was not observed in any of the infants studied. Hence, there is no evidence that periodic breathing is the result of diaphragmatic muscle fatigue. This finding suggests that the effect of drugs such as theophylline in eliminating periodic breathing may be unrelated to the fact that they also reduce fatigue.

Independent Processing across Spatial Frequency in Moving Broadband Patterns

Perception ◽  
1997 ◽  
Vol 26 (8) ◽  
pp. 961-976 ◽  
Author(s):  
Richard A Eagle
Keyword(s):  
Spatial Frequency ◽  
Visual System ◽  
High Frequency ◽  
Spatial Scales ◽  
Power Spectra ◽  
Frequency Noise ◽  
Low Contrast ◽  
Task Requirements ◽  
Noise Frequency ◽  
Frame Motion

The aim of the experiments was to discover whether the visual system has independent access to motion information at different spatial scales when presented with a broadband stimulus. Subjects were required to discriminate between a pair of two-frame motion sequences, one containing a coherently displacing pattern and the other containing a pattern with high-frequency noise. The stimuli were either narrowband (1 octave) or broadband (6 octaves spanning 0.23–15.0 cycles deg−1) and their power spectra were either flat or followed a 1 /f2 function. For the broadband stimuli, noise was introduced cumulatively into increasingly lower frequencies. For the narrowband stimuli, noise was introduced into the same frequency band as the signal. All stimuli could be defined by the lowest noise frequency ( n1) they contained. For each stimulus, the largest spatial displacement across the two frames at which the task could be performed was measured ( dmax). For the narrowband stimuli, dmax increased as n1 was lowered. This was true over the entire frequency range for the 1 /f2 stimuli, though the task became impossible for the flat-spectrum stimuli at the lowest frequencies. This is attributed to the very low contrast of these latter stimuli. The dmax values for the broadband stimuli tended to shadow those of the narrowband stimuli with the equivalent values of n1 being around 25% lower. The data were modelled by spatiotemporally filtering the stimuli and considering the amount of directional power in the signal and noise sequences. The results suggest that there must be multiple spatial-frequency channels in operation, and that for broadband patterns the visual system has perceptual access to these individual channel outputs, utilising different filters depending on the task requirements.

Spectral Analysis of Systolic Blood Pressure and Heart Rate after Heart Transplantation in Children

1995 ◽  
Vol 88 (1) ◽  
pp. 95-102 ◽  
Author(s):  
Isabelle Constant ◽  
Arlette Girard ◽  
Jérôme Le Bidois ◽  
Elizabeth Villain ◽  
Dominique Laude ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Heart Rate Variability ◽  
Heart Transplantation ◽  
Systolic Blood Pressure ◽  
High Frequency ◽  
Power Spectra ◽  
Critical Factor ◽  
Group B ◽  
Cardiac Afferents

1. The aim of the study was to examine the short-term variability in blood pressure and heart rate in 19 children who had received heart transplants and in eight normal control children. 2. Blood pressure was determined by a finger arterial pressure device. We examined the power spectra for heart rate and systolic blood pressure in the supine and tilted positions. In addition, we studied the acute changes in blood pressure and heart rate during active standing. 3. In the transplanted children we could distinguish two groups (groups A and B) in whom heart rate variability differed, although in both it was greatly reduced compared with controls (group C). In group A there were no significant fluctuations in the mid-frequency range for heart rate. The gain of the relationship between systolic blood pressure and heart rate was very low and there were virtually no heart rate changes associated with passive tilting. 4. By contrast, in group B transplant patients the heart rate variability, as assessed by standard deviation, was about half that of normal controls. The power spectra attenuation was greater in the high-frequency than in the mid-frequency bands. On passive tilting the latter became enhanced, but not the high-frequency variability. On active standing the tachycardic response was about half that of controls. The findings suggest some reinnervation involving cardiac sympathetic fibres to a greater degree than the fast-responding vagal fibres. 5. In both groups A and B the drop in systolic blood pressure observed early in active standing was about 4–6 times as great as in controls. One possible mechanism could be the loss of cardiac afferents. 6. Time since operation was a critical factor for reinnervation, since all subjects from group B were transplanted more than 44 months prior to the recording. 7. We conclude that in a proportion of children who have received heart transplantation there is a delayed reinnervation of the heart, which probably involves sympathetic effectors rather than the vagus.

scholarly journals Lung mechanical and vascular changes during positive- and negative-pressure lung inflations: importance of reference pressures in the pulmonary vasculature

2009 ◽  
Vol 106 (3) ◽  
pp. 935-942 ◽  
Author(s):  
Ferenc Peták ◽  
Gergely Albu ◽  
Enikö Lele ◽  
Zoltán Hantos ◽  
Denis R. Morel ◽  
...  
Keyword(s):  
Negative Pressure ◽  
Time Windows ◽  
Low Frequency ◽  
Lung Mechanics ◽  
Pulmonary Vasculature ◽  
Positive Pressure ◽  
Vascular Changes ◽  
Inflation Pressure ◽  
Lung Inflation ◽  
Impedance Data

The continuous changes in lung mechanics were related to those in pulmonary vascular resistance (Rv) during lung inflations to clarify the mechanical changes in the bronchoalveolar system and the pulmonary vasculature. Rv and low-frequency lung impedance data (Zl) were measured continuously in isolated, perfused rat lungs during 2-min inflation-deflation maneuvers between transpulmonary pressures of 2.5 and 22 cmH2O, both by applying positive pressure at the trachea and by generating negative pressure around the lungs in a closed box. Zl was averaged and evaluated for 2-s time windows; airway resistance (Raw), parenchymal damping and elastance (H) were determined in each window. Lung inflation with positive and negative pressures led to very similar changes in lung mechanics, with maximum decreases in Raw [−68 ± 4 (SE) vs. −64 ± 18%] and maximum increases in H (379 ± 36 vs. 348 ± 37%). Rv, however, increased with positive inflation pressure (15 ± 1%), whereas it exhibited mild decreases during negative-pressure expansions (−3 ± 0.3%). These results demonstrate that pulmonary mechanical changes are not affected by the opposing modes of lung inflations and confirm the importance of relating the pulmonary vascular pressures in interpreting changes in Rv.

Recovery of breathing pattern after 15 min of cerebral ischemia in rabbits

1990 ◽  
Vol 69 (5) ◽  
pp. 1676-1681 ◽  
Author(s):  
R. Pluta ◽  
J. R. Romaniuk
Keyword(s):  
Cerebral Ischemia ◽  
Neural Control ◽  
Breathing Pattern ◽  
Respiratory Pattern ◽  
Lung Inflation ◽  
Brachiocephalic Trunk ◽  
Precise Analysis ◽  
Neural Control Of Breathing ◽  
Recurrent Laryngeal Nerves ◽  
The Brain

The study was undertaken to ascertain the neural control of breathing and vagal reflexes during and after cerebral ischemia. The experiments were performed on anesthetized, paralyzed, and artificially ventilated rabbits. Cerebral ischemia was induced by reversible intrathoracic occlusion of the brachiocephalic trunk and the left subclavian and both internal thoracic arteries for 15 min. The effect of cerebral ischemia on breathing pattern was assessed by monitoring the integrated activities of phrenic and recurrent laryngeal nerves. Ischemia produced enhancement of breathing followed by apnea and gasping. During enhanced breathing as well as during gasping, the inspiratory-inhibiting effect of lung inflation (Breuer-Hering reflex) was abolished. When brain circulation was restored, respiratory activity started with gasps, which later were intermingled with eupneic type of inspirations. During the onset of a eupneic breath, lung inflation produced inspiratory facilitation but never an inhibition. However, after 30 min of recovery from cerebral ischemia, the Breuer-Hering reflex was restored. Results show that precise analysis of vagal reflexes and respiratory pattern during ischemia and resuscitation may be used as an indicator of resumption of autonomic activity in the brain stem.

Effects on respiratory pattern of focal cooling in the medulla of the dog

1988 ◽  
Vol 65 (5) ◽  
pp. 2004-2010 ◽  
Author(s):  
M. Adams ◽  
T. Chonan ◽  
N. S. Cherniack ◽  
C. von Euler
Keyword(s):  
Respiratory Rhythm ◽  
Nucleus Ambiguus ◽  
Respiratory Pattern ◽  
Respiratory Drive ◽  
Timing Effect ◽  
Diaphragm Electrical Activity ◽  
Inspiratory Activity ◽  
Ventral Medullary Surface ◽  
Focal Cooling

Studies in cats have shown that, in addition to respiratory neuron groups in the dorsomedial (DRG) and ventrolateral (VRG) medulla, neural structures in the most ventral medullary regions are important for the maintenance of respiratory rhythm. The purpose of this study was to determine whether a similar superficially located ventral region was present in the dog and to assess the role of each of the other regions in the canine medulla important in the control of breathing, in 20 anesthetized, vagotomized, and artificially ventilated dogs, a cryoprobe was used to cool selected regions of the medulla to 15-20 degrees C. Respiratory output was determined from phrenic nerve or diaphragm electrical activity. Cooling in or near the nucleus of the solitary tract altered timing and produced little change in the amplitude or rate of rise of inspiratory activity; lengthening of inspiratory time was the most common timing effect observed. Cooling in ventrolateral regions affected the amplitude and rate of rise of respiratory activity. Depression of neural tidal volume and apnea could be produced by unilateral cooling in two ventrolateral regions: 1) near the nucleus ambiguus and nucleus para-ambiguus and 2) just beneath the ventral medullary surface. These findings indicate that in the dog dorsomedial neural structures influence respiratory timing, whereas more ventral structures are important to respiratory drive.

Mechanoreceptor modulation of endogenous respiratory rhythms in vertebrates

1990 ◽  
Vol 259 (5) ◽  
pp. R898-R910 ◽  
Author(s):  
W. K. Milsom
Keyword(s):  
Breathing Pattern ◽  
Respiratory Rhythm ◽  
Flow Distribution ◽  
Respiratory Pattern ◽  
Respiratory Drive ◽  
Lung Inflation ◽  
Phase Switching ◽  
Separate Control ◽  
Regulation Of Breathing ◽  
Receptor Input

While pulmonary mechanoreceptors appear to play little or no role in determining the eupneic breathing pattern in some species of vertebrates, they do in others as well as in all species under conditions of elevated respiratory drive. Tonic and phasic inputs from this receptor group have independent roles in determining breathing pattern. Thus withholding lung inflation produces very different results from receptor denervation. There are at least five phases to the respiratory cycle that appear to be under separate control. Tonic receptor input is involved primarily in regulating the length of the respiratory pause, which can occur at the end of inspiration or expiration, depending on the species. Phasic receptor input has different effects during different phases of the cycle as well as different effects at different times during a single phase. This activity contributes to phase switching during the ventilation cycle and thus to the regulation of breathing frequency and tidal volume. The significance of the modulatory effects of phasic input on the duration of different phases of the ventilation cycle is not totally clear, but the evidence suggests that phasic input acts to stabilize the respiratory pattern and may be instrumental in optimizing the breathing pattern in terms of ergometric costs. This appears to be the case in all vertebrate classes, despite dramatic differences in the mechanical events associated with ventilation arising from different respiratory pumps. These receptors also appear to have significant roles other than those associated with modulation of respiratory rhythm, particularly in lower vertebrates. Many of these roles, such as maintaining the integrity of the gill curtain in fish or buoyancy control and regulation of blood flow distribution in reptiles, may be as important as their role in modulating the endogenous rhythm.

Respiratory motor responses to cranial nerve afferent stimulation in rats

1996 ◽  
Vol 271 (4) ◽  
pp. R1054-R1062 ◽  
Author(s):  
F. Hayashi ◽  
D. R. McCrimmon
Keyword(s):  
Cranial Nerve ◽  
Superior Laryngeal Nerve ◽  
Single Pulse ◽  
Short Latency ◽  
Lung Inflation ◽  
Dorsal Respiratory Group ◽  
Inspiratory Activity ◽  
Pharyngeal Branch ◽  
Pulse Stimulation ◽  
Stimulation Of

It was hypothesized that, because rats appear to lack a prominent disynaptic projection from the dorsal respiratory group to phrenic motoneurons (Phr), they would lack the short-latency excitation of Phr output seen in cats in response to stimulation of some cranial nerve afferents. Single-pulse superior laryngeal nerve (SLN) stimulation elicited a short-latency bilateral excitation of glossopharyngeal (IX) and hypoglossal (XII) nerves and an ipsilateral excitation of pharyngeal branch of vagus (PhX) in 67% of rats, but no excitation of Phr. Vagus (X) stimulation elicited a bilateral excitation of Phr and a predominantly ipsilateral excitation of IX and PhX. Single-pulse stimulation of SLN or X also elicited longer-latency, bilateral decreases in activity of all recorded nerves. Repetitive stimulation (50 Hz) of SLN or X suppressed inspiratory activity and prolonged expiration. Lung inflation (7.5 cmH2O) inhibited Phr and PhX activity; X stimulation inhibited Phr but prolonged PhX activity. In conclusion, rats predictably lack the SLN-induced short latency Phr excitation but exhibit other short latency reflexes for which the underlying circuitry is not clear.

Heart rate variability and dissociation in panic disorder

2011 ◽  
Vol 26 (S2) ◽  
pp. 147-147
Author(s):  
T. Diveky ◽  
D. Kamaradova ◽  
A. Grambal ◽  
K. Latalova ◽  
J. Prasko ◽  
...  
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Panic Disorder ◽  
Frequency Band ◽  
High Frequency ◽  
Power Spectra ◽  
Low Frequency ◽  
Very Low Frequency ◽  
Significant Difference ◽  
Before And After

The aim of our study is to measure very low frequency band (VLF), low frequency band (LF) and high frequency band (HF) components of R-R interval during orthostatic experiment in panic disorder patients before and after treatment.MethodsWe assessed heart rate variability in 19 patients with panic disorder before and after 6-weeks treatment with antidepressants combined with CBT and 18 healthy controls. They were regularly assessed on the CGI, BAI and BDI. Heart rate variability was assessed during 5 min standing, 5 min supine and 5 min standing positions before and after the treatment. Power spectra were computed using a fast Fourier transformation for very low frequency - VLF (0.0033 - 0.04 Hz), low-frequency - LF (0.04-0.15 Hz) and high frequency - HF (0.15-0.40 Hz) powers.Results19 panic disorder patients entered a 6-week open-label treatment study with combination of SSRI and cognitive behavioral therapy. A combination of CBT and pharmacotherapy proved to be the effective treatment of patients. They significantly improved in all rating scales. There were highly statistical significant differences between panic patients and control group in all components of power spectral analysis in 2nd and in two component of 3rd (LF and HF in standing) positions. There was also statistically significant difference between these two groups in LF/HF ratio in supine position (2nd). During therapy there was tendency to increasing values in all three positions in components of HRV power spectra, but there was only statistically significant increasing in HF1 component.Supported by project IGA MZ ČR NS 10301-3/2009

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