Regulation of the sympathetic nerve discharge bursting pattern during heat stress

1998 ◽  
Vol 275 (6) ◽  
pp. R1992-R2001 ◽  
Author(s):  
Michael J. Kenney ◽  
Dale E. Claassen ◽  
Michelle R. Bishop ◽  
Richard J. Fels
Keyword(s):  
Heat Stress ◽  
Frequency Domain ◽  
Phrenic Nerve ◽  
Sympathetic Nerve ◽  
Core Body Temperature ◽  
Low Frequency ◽  
Sympathetic Nerves ◽  
Frequency Components ◽  
Pattern Transformation ◽  
Nerve Discharge

Frequency-domain analyses were used to determine the effect of heat stress on the relationships between the discharge bursts of sympathetic nerve pairs and sympathetic and phrenic nerve pairs in chloralose-anesthetized rats. Sympathetic nerve discharge (SND) was recorded from the renal, splanchnic, splenic, and lumbar nerves during increases in core body temperature (Tc) from 38 to 41.4 ± 0.3°C. The following observations were made: 1) hyperthermia transformed the cardiac-related bursting pattern of SND to a pattern that contained low-frequency, non-cardiac-related bursts, 2) the pattern transformation was uniform in regionally selective sympathetic nerves, 3) hyperthermia enhanced the frequency-domain coupling between SND and phrenic nerve bursts, and 4) low-frequency SND bursts recorded during hyperthermia contained significantly more activity than cardiac-related bursts. We conclude that acute heat stress profoundly affects the organization of neural circuits responsible for the frequency components in sympathetic nerve activity and that SND pattern transformation provides an important strategy for increasing the level of activity in sympathetic nerves during increased Tc.

scholarly journals Cold stress alters characteristics of sympathetic nerve discharge bursts

1999 ◽  
Vol 87 (2) ◽  
pp. 732-742 ◽  
Author(s):  
Michael J. Kenney ◽  
Dale E. Claassen ◽  
Richard J. Fels ◽  
Cristina S. Saindon
Keyword(s):  
Body Temperature ◽  
Cold Stress ◽  
Sympathetic Nerve ◽  
Mild Hypothermia ◽  
Core Body Temperature ◽  
Low Frequency ◽  
Sympathetic Nerves ◽  
Level Of Activity ◽  
Core Body ◽  
Nerve Discharge

Frequency-domain analyses were used to determine the effect of cold stress on the relationships between the discharge bursts of sympathetic nerve pairs, sympathetic and aortic depressor nerve pairs, and sympathetic and phrenic nerve pairs in chloralose-anesthetized, baroreceptor-innervated rats. Sympathetic nerve discharge (SND) was recorded from the renal, lumbar, splanchnic, and adrenal nerves during decreases in core body temperature from 38 to 30°C. The following observations were made. 1) Hypothermia produced nonuniform changes in the level of activity in regionally selective sympathetic nerves. Specifically, cold stress increased lumbar and decreased renal SND but did not significantly change the level of activity in splanchnic and adrenal nerves. 2) The cardiac-related pattern of renal, lumbar, and splanchnic SND bursts was transformed to a low-frequency (0–2 Hz) pattern during cooling, despite the presence of pulse-synchronous activity in arterial baroreceptor afferents. 3) Peak coherence values relating the discharges between sympathetic nerve pairs decreased at the cardiac frequency but were unchanged at low frequencies (0–2 Hz), indicating that the sources of low-frequency SND bursts remain prominently coupled during progressive reductions in core body temperature. 4) Coherence of discharge bursts in phrenic and renal sympathetic nerve pairs in the 0- to 2-Hz frequency band increased during mild hypothermia (36°C) but decreased during deep hypothermia (30°C). We conclude that hypothermia profoundly alters the organization of neural circuits involved in regulation of sympathetic nerve outflow to selected regional circulations.

Paraventricular nucleus bicuculline alters frequency components of sympathetic nerve discharge bursts

2001 ◽  
Vol 281 (3) ◽  
pp. H1233-H1241 ◽  
Author(s):  
Michael J. Kenney ◽  
Mark L. Weiss ◽  
Kaushik P. Patel ◽  
Yan Wang ◽  
Richard J. Fels
Keyword(s):  
Paraventricular Nucleus ◽  
Sympathetic Nerve ◽  
Cardiac Cycle ◽  
Low Frequency ◽  
Sympathetic Nerves ◽  
Receptor Antagonism ◽  
Gaba Agonist ◽  
Frequency Components ◽  
Induced Changes ◽  
Nerve Discharge

Autospectral and coherence analyses were used to determine the effect of paraventricular nucleus (PVN) GABAA receptor antagonism [microinfusion or microinjections of bicuculline methiodide (BMI) 100 pmoles] on sympathetic nerve discharge (SND) frequency components (bursting pattern and relationships between discharges in regionally selective nerves) in α-chloralose-anesthetized rats. SND was recorded from the renal, splenic, and lumbar nerves. The following observations were made. First, PVN BMI microinjections, but not PVN saline or cortical BMI microinjections, transformed the cardiac-related SND bursting pattern in baroreceptor-innervated rats to one characterized by the presence of low-frequency bursts not synchronized to the cardiac cycle or phrenic nerve discharge bursts. Second, SND pattern changes were similar in the renal, splenic, and lumbar nerves, and peak coherence values relating low-frequency bursts in sympathetic nerve pairs (renal-splenic, renal-lumbar, and splenic-lumbar) were significantly increased from preinjection control after PVN BMI microinjection. Third, PVN BMI microinjections significantly increased the coupling between low-frequency SND bursts in baroreceptor-denervated rats. Finally, PVN BMI-induced changes in the SND bursting pattern were not observed after PVN pretreatment with muscimol (GABA agonist, 1 nmole). We conclude that PVN GABAA receptor antagonism profoundly alters the frequency components in sympathetic nerves.

Frequency characteristics of sympathetic nerve discharge in anesthetized rats

1994 ◽  
Vol 267 (3) ◽  
pp. R830-R840 ◽  
Author(s):  
M. J. Kenney
Keyword(s):  
Frequency Domain ◽  
Frequency Band ◽  
Sympathetic Nerve ◽  
Acute Stress ◽  
Sympathetic Nerves ◽  
Frequency Characteristics ◽  
Total Power ◽  
Dynamic Nature ◽  
Frequency Components ◽  
Nerve Discharge

Frequency-domain analyses were used to characterize basal sympathetic nerve discharge (SND) and to determine the relationships between the activity recorded simultaneously from sympathetic nerves in chloralose-anesthetized, baroreceptor-innervated rats. Discharges were recorded from the splanchnic, renal, and lumbar nerves. The following observations were made. 1) Approximately 65-75% of total power in SND was contained below 9 Hz in either baroreceptor-innervated rats or baroreceptor-denervated rats. 2) Coherence values relating the activity of two nerves were significantly different from zero within this frequency band. 3) The interval between the discharges of two sympathetic nerves was either frequency dependent or constant within the coherent frequency band. 4) The frequency components of SND and the relationships between the activity in two sympathetic nerves could be altered during periods of acute stress. These results suggest that the system responsible for basal SND in rats is composed of either multiple sympathetic generators or multiple filters arranged in parallel, which are capable of producing different outputs. The dynamic nature of these circuits was revealed by the changes that occurred during periods of acute stress.

Coupled oscillators account for the slow rhythms in sympathetic nerve discharge and phrenic nerve activity

1997 ◽  
Vol 272 (4) ◽  
pp. R1314-R1324 ◽  
Author(s):  
S. Zhong ◽  
S. Y. Zhou ◽  
G. L. Gebber ◽  
S. M. Barman
Keyword(s):  
Phrenic Nerve ◽  
Sympathetic Nerve ◽  
Coupled Oscillators ◽  
Sympathetic Nerves ◽  
Partial Coherence ◽  
Coherence Analysis ◽  
Nerve Activity ◽  
Phrenic Nerve Activity ◽  
Slow Rhythm ◽  
Nerve Discharge

Phase-locked slow rhythms in sympathetic nerve discharge (SND) and phrenic nerve activity (PNA) are generally thought to arise from a common brain stem "cardiorespiratory" oscillator. The results obtained in vagotomized and baroreceptor-denervated cats anesthetized with pentobarbital sodium do not support this view. First, partial coherence analysis revealed that the discharges of pairs of sympathetic nerves remained correlated at the frequency of the central respiratory cycle after mathematical removal of the portion of these signals common to PNA. The residual coherence suggests that the slow rhythm in SND is dependent on central mechanisms in addition to those responsible for rhythmic PNA. Second, the rhythms in SND and PNA became coupled in a 2:1 relationship during either moderate systemic hypocapnia or hypercapnia. Third, the slow rhythm in SND was maintained when rhythmic PNA was eliminated during extreme hypocapnia. Fourth, during extreme hypercapnia, coherence of the rhythms in SND and PNA was drastically reduced. These results suggest that the slow rhythms in SND and PNA arise from separate oscillators that are normally coupled.

The 10-Hz rhythm in sympathetic nerve discharge

1992 ◽  
Vol 262 (6) ◽  
pp. R1006-R1014 ◽  
Author(s):  
S. M. Barman ◽  
G. L. Gebber ◽  
S. Zhong
Keyword(s):  
Frequency Domain ◽  
Sympathetic Nerve ◽  
Sympathetic Nerves ◽  
Domain Analysis ◽  
Frequency Domain Analysis ◽  
Frequency Dependent ◽  
New Findings ◽  
Decerebrate Cats ◽  
Nerve Discharge

Frequency-domain analysis was used to characterize the relationships among the rhythmic discharges recorded simultaneously from two to four sympathetic nerves in unanesthetized decerebrate cats. The major new findings were as follows. 1) The 10-Hz rhythmic discharges of different nerves cohered strongly in baroreceptor-innervated and -denervated cats. 2) The interval between the discharges of two nerves was frequency dependent in the 10-Hz band in some cats, supporting the view that the 10-Hz rhythm is generated by multiple central circuits that are coupled. 3) In some cases the central circuits responsible for the 10-Hz rhythms nonuniformly affected different nerves. 4) In baroreceptor-innervated cats the coherence values for the cardiac-related discharges of any two nerves were significantly higher than those for the 10-Hz rhythms. 5) In baroreceptor-denervated cats the 10-Hz rhythmic discharges of different nerves cohered more strongly than the 2- to 6-Hz rhythms. 6) The 10-Hz rhythm usually was not a harmonic of the 2- to 6-Hz or cardiac-related rhythm. Thus these rhythms are generated independently.

Sympathetic nerve responses to hyperthermia in the anesthetized rat

1995 ◽  
Vol 78 (3) ◽  
pp. 881-889 ◽  
Author(s):  
M. J. Kenney ◽  
C. C. Barney ◽  
T. Hirai ◽  
C. V. Gisolfi
Keyword(s):  
Heart Rate ◽  
Sympathetic Nerve ◽  
Neural Circuits ◽  
Core Body Temperature ◽  
Sympathetic Nerves ◽  
Basic Pattern ◽  
Sympathetic Nervous ◽  
Core Body ◽  
Cardiopulmonary Baroreceptors ◽  
Nerve Discharge

The aim of the present study was to characterize the sympathetic nerve responses to hyperthermia in chloralose-anesthetized rats. Discharges were recorded from the renal, lumbar, and splanchnic sympathetic nerves. Mean arterial pressure, heart rate, and sympathetic nerve discharge (SND) were recorded continuously during progressive increases in core body temperature (Tc) from 38.0 to 41.0 degrees C. The following observations were made: 1) significant increases in renal, lumbar, and splanchnic SND were observed during hyperthermia; 2) autospectral analysis of renal and lumbar SND revealed that the frequency distribution of SND can be altered during progressive increases in Tc; and 3) increases in splanchnic SND to acute heating were similar in baroreceptor-innervated and -denervated rats. We conclude that 1) hyperthermia is a potent stimulus to the sympathetic nervous system and increases the activity in three sympathetic nerves that innervate different regional arterial beds, 2) acute heating influences the neural circuits involved in generating SND as evidenced by changes in the basic pattern of renal and lumbar SND, and 3) the increase in splanchnic SND during hyperthermia is not opposed by the arterial and cardiopulmonary baroreceptors.

scholarly journals Multi-scale time-frequency domain full waveform inversion with a weighted local correlation-phase misfit function

2019 ◽  
Vol 16 (6) ◽  
pp. 1017-1031 ◽  
Author(s):  
Yong Hu ◽  
Liguo Han ◽  
Rushan Wu ◽  
Yongzhong Xu
Keyword(s):  
Frequency Domain ◽  
Seismic Data ◽  
Waveform Inversion ◽  
Low Frequency ◽  
Full Waveform Inversion ◽  
Local Correlation ◽  
Time Frequency ◽  
Model Dependence ◽  
Full Waveform ◽  
Frequency Components

Abstract Full Waveform Inversion (FWI) is based on the least squares algorithm to minimize the difference between the synthetic and observed data, which is a promising technique for high-resolution velocity inversion. However, the FWI method is characterized by strong model dependence, because the ultra-low-frequency components in the field seismic data are usually not available. In this work, to reduce the model dependence of the FWI method, we introduce a Weighted Local Correlation-phase based FWI method (WLCFWI), which emphasizes the correlation phase between the synthetic and observed data in the time-frequency domain. The local correlation-phase misfit function combines the advantages of phase and normalized correlation function, and has an enormous potential for reducing the model dependence and improving FWI results. Besides, in the correlation-phase misfit function, the amplitude information is treated as a weighting factor, which emphasizes the phase similarity between synthetic and observed data. Numerical examples and the analysis of the misfit function show that the WLCFWI method has a strong ability to reduce model dependence, even if the seismic data are devoid of low-frequency components and contain strong Gaussian noise.

Relationships between activity of sympathetic nerve pairs: phase and coherence

1990 ◽  
Vol 259 (3) ◽  
pp. R549-R560 ◽  
Author(s):  
B. Kocsis ◽  
G. L. Gebber ◽  
S. M. Barman ◽  
M. J. Kenney
Keyword(s):  
Frequency Band ◽  
Sympathetic Nerve ◽  
Coherence Function ◽  
Sympathetic Nerves ◽  
Phase Spectrum ◽  
Central System ◽  
Functional States ◽  
Alpha Chloralose ◽  
Constant Interval ◽  
Nerve Discharge

The coherence function and phase spectrum were used to study the relationships between the discharges of sets of two postganglionic or preganglionic sympathetic nerves in baroreceptor-denervated cats anesthetized with either 5,5-diallylbarbiturate-urethan or alpha-chloralose. Most of the power in sympathetic nerve discharge was contained between 2 and 6 Hz. The coherence values relating the activity of two nerves were significantly different from zero within this frequency band. The phase spectrum was either linear or complex (i.e., showed changes in slope) within the coherent frequency band. We observed three patterns of relationship. The first pattern was characterized by a constant interval between activity in different sympathetic nerves within the coherent frequency band. The second pattern was characterized by a frequency-dependent interval. The third pattern was characterized by uncoupling of the 2- to 6-Hz rhythms in the discharges of different nerves. Switching between these patterns was observed. We suggest that the three patterns reflect different functional states of the central system responsible for the 2- to 6-Hz rhythm. Two models of this system are entertained. The first model is one of a system of coupled oscillators while filtering circuits that receive common inputs are the elements of the second model.

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