Differential relationships among the 10-Hz rhythmic discharges of sympathetic nerves with different targets

1994 ◽  
Vol 267 (2) ◽  
pp. R387-R399 ◽  
Author(s):  
G. L. Gebber ◽  
S. Zhong ◽  
S. M. Barman ◽  
Y. Paitel ◽  
H. S. Orer
Keyword(s):  
Brain Stem ◽  
Cross Talk ◽  
Sympathetic Nerve ◽  
Sympathetic Nerves ◽  
Partial Coherence ◽  
Sharp Peak ◽  
Coherence Analysis

Partial coherence analysis was used to remove the influences of the central circuits controlling a sympathetic nerve (as reflected by its discharges) on the coherence of the 10-Hz discharges of other sympathetic nerves in unanesthetized decerebrate or urethan-anesthetized cats. In many cases, partialization reduced but did not eliminate the sharp peak near 10 Hz in the coherence functions relating the discharges of sympathetic nerve pairs. This observation implies that the central sources of the 10-Hz rhythmic discharges of any nerve are not identical to those responsible for the rhythm recorded from any other nerve. Partial coherence analysis also revealed differential relationships among the 10-Hz rhythmic discharges of sympathetic nerves with different targets. Importantly, the pattern of differential relationships observed in one experiment could be the reverse of that in the next. Although the basis for the differential relationships is not yet clear, nonuniform coupling of multiple brain stem 10-Hz oscillators and/or nonuniform cross talk between spinal circuits controlling different sympathetic nerves may be involved.

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.

Partial Spectral Analysis of Cardiac-Related Sympathetic Nerve Discharge

2000 ◽  
Vol 84 (3) ◽  
pp. 1168-1179 ◽  
Author(s):  
Peter D. Larsen ◽  
Craig D. Lewis ◽  
Gerard L. Gebber ◽  
Sheng Zhong
Keyword(s):  
Sympathetic Nerve ◽  
Phase Locking ◽  
Sympathetic Nerves ◽  
Heart Beat ◽  
Partial Coherence ◽  
Coherence Analysis ◽  
Clear Peak ◽  
The Relationship ◽  
Mode Of Coordination ◽  
Nerve Discharge

We have studied the relationship between pulse synchronous baroreceptor input (represented by the arterial pulse, AP) and the cardiac-related rhythm in sympathetic nerve discharge (SND) of urethan-anesthetized cats by using partial autospectral and partial coherence analysis. Partial autospectral analysis was used to mathematically remove the portion of SND that can be directly attributed to the AP, while partial coherence analysis was used to removed the portion of the relationship between the discharges of sympathetic nerve pairs that can be attributed to linear AP-SND relationships that are common to the nerves. The ordinary autospectrum of SND (ASSND) and coherence functions relating the discharges of nerve pairs (CohSND-SND) contained a peak at the frequency of the heart beat. When the predominant mode of coordination between AP and SND was a phase walk, partialization of the autospectra of SND with AP (ASSND/AP) left considerable power in the cardiac-related band. In contrast, when the predominant mode of coordination between AP and SND was phase-locking, there was virtually no cardiac-related activity remaining in ASSND/AP. Partialization of CohSND-SND with AP reduced the peak coherence within the cardiac-related band in both modes of coordination but to a much greater extent during phase-locking. After baroreceptor denervation, CohSND-SND at the cardiac frequency remained significant, although a clear peak above background coherence was no longer apparent. These results are consistent with a model in which the central circuits controlling different sympathetic nerves share baroreceptor inputs and in addition are physically interconnected. The baroreceptor-sympathetic relationship contains both linear and nonlinear components, the former reflected by phase-locking and the latter by phase walk. The residual power in ASSND/AP during phase walk can be attributed to the nonlinear relationship, and the residual peak in partialized nerve-to-nerve coherence (CohSND-SND/AP) arises largely from nonlinearities that are common to the two nerves. During both phase walk and phase-locking, in addition to common nonlinear AP-SND relationships, coupling of the central circuits generating the nerve activities may contribute to CohSND-SND/APbecause significant CohSND-SND was still observed following baroreceptor denervation.

Preferential correlations of a medullary neuron's activity to different sympathetic outflows as revealed by partial coherence analysis

1995 ◽  
Vol 74 (1) ◽  
pp. 474-478 ◽  
Author(s):  
M. I. Cohen ◽  
Q. Yu ◽  
W. X. Huang
Keyword(s):  
Sympathetic Nerves ◽  
Partial Coherence ◽  
Coherence Analysis ◽  
Significant Peak ◽  
Neuron Populations ◽  
Cervical Sympathetic ◽  
Decerebrate Cats ◽  
Differential Connectivity ◽  
Coherence Spectrum ◽  
Medullary Neurons

1. In vagotomized, paralyzed, decerebrate cats, simultaneous recordings were taken from one or more sympathetic nerves [cervical sympathetic (CS), inferior cardiac (IC), splanchnic (SP)] and from medullary neurons in vasomotor-related regions. Coherence analyses were used to ascertain the presence of sympathetic rhythms (2-6 Hz or "3-Hz rhythm," 7-13 Hz or "10-Hz rhythm") that were correlated between different signals. The occurrence of a significant peak at such a frequency in a unit-nerve coherence spectrum allowed the identification of a medullary neuron as sympathetic related. 2. A serendipitous example is given of a rostral ventrolateral medullary neuron that had significant unit-nerve 10-Hz coherence peaks for three sympathetic nerves (CS, IC, SP); but, as revealed by partial coherence analysis, the unit activity's correlation with one nerve's activity could be partially or completely dependent on its correlation with other nerve activities. Thus in this case the unit-CS and unit-IC coherences at 10 Hz were completely dependent on the SP rhythm, whereas the unit-SP coherence was not significantly affected by the CS and IC rhythms. This asymmetry suggests that the neuron was preferentially connected to SP-generating medullary circuits. 3. This example indicates the strength of partial coherence analysis as a means of studying differential connectivity between medullary sympathetic-related neurons and sympathetic output neuron populations.

Differential control of sympathetic nerve discharge by the brain stem

1984 ◽  
Vol 247 (3) ◽  
pp. R513-R519 ◽  
Author(s):  
S. M. Barman ◽  
G. L. Gebber ◽  
F. R. Calaresu
Keyword(s):  
Brain Stem ◽  
Sympathetic Nerve ◽  
Sympathetic Nerves ◽  
Frequency Component ◽  
External Carotid ◽  
Medullary Raphe ◽  
Reticular Neurons ◽  
Differential Control ◽  
The Brain ◽  
Raphe Neurons

This investigation was designed to test the hypothesis that the brain stem differentially controls the basal discharges of postganglionic sympathetic nerves distributed to different organs. Previous studies have shown that the 2- to 6-Hz activity pattern in sympathetic nerves of the baroreceptor-denervated cat originates in the brain stem. In the current study, autocorrelation and power spectral analyses were used to compare the 2- to 6-Hz frequency components of the simultaneously recorded discharges of postganglionic sympathetic nerve pairs (inferior cardiac and renal; external carotid and renal) in baroreceptor-denervated cats anesthetized with sodium diallylbarbiturate and urethan (Dialurethane). In addition, spike-triggered averaging was used to compare the relative strengths of coupling of the basal discharges of single ventrolateral medullary reticular or medullary raphe neurons to activity in postganglionic sympathetic nerve pairs. The major findings of the study are as follows: 1) the predominant 2- to 6-Hz frequency component in the basal discharges of one sympathetic nerve often was different from that in the discharges of a second nerve, and 2) the activity of approximately one-third of ventrolateral medullary reticular neurons and one-half of medullary raphe neurons (with sympathetic-related activity) was differentially related to the discharges of postganglionic nerve pairs. These results support the view that the brain stem reticular formation and raphe complex exert their influences on different sympathetic nerves in a nonuniform fashion.

Coordination of the cardiac-related discharges of sympathetic nerves with different targets

1994 ◽  
Vol 267 (2) ◽  
pp. R400-R407 ◽  
Author(s):  
G. L. Gebber ◽  
S. Zhong ◽  
S. M. Barman ◽  
H. S. Orer
Keyword(s):  
Heart Rate ◽  
Coherence Function ◽  
Sympathetic Nerves ◽  
Partial Coherence ◽  
Coherence Analysis ◽  
Arterial Pulse ◽  
Nerve Activity ◽  
Multiple Routes ◽  
Rate Frequency ◽  
Decerebrate Cats

Partial coherence analysis was used to remove the influences of pulse-synchronous baroreceptor nerve activity (as reflected by the arterial pulse) on the coherence of the cardiac-related discharges of sympathetic nerve pairs in unanesthetized decerebrate cats. It can be predicted that the peak at the heart rate frequency in the ordinary coherence function relating the discharges of two nerves will be eliminated by either partialization using the arterial pulse or surgical baroreceptor denervation, if the central circuits controlling the nerves share baroreceptor inputs but are not interconnected. Contrary to this prediction, in many experiments the peak was not eliminated by partialization using the arterial pulse. Moreover, partialization often nonuniformly reduced the peaks at the heart rate frequency in the coherence functions for different nerve pairs. These results are consistent with a model of multiple routes over which baroreceptor influences are distributed to the central circuits controlling different sympathetic nerves. Specifically, we propose that the direct route from the baroreceptors to each of the central circuits is complemented by cross talk among the central circuits.

Brain stem neuronal types with activity patterns related to sympathetic nerve discharge

1981 ◽  
Vol 240 (5) ◽  
pp. R335-R347 ◽  
Author(s):  
S. M. Barman ◽  
G. L. Gebber
Keyword(s):  
Brain Stem ◽  
Sympathetic Nerve ◽  
Activity Patterns ◽  
Sympathetic Nerves ◽  
Eeg Activity ◽  
Spike Triggered Averaging ◽  
Neuronal Types ◽  
Discharge Patterns ◽  
Electroencephalogram Eeg ◽  
Nerve Discharge

The relationships among the spontaneous activity of single neurons in the cat medulla and inferior cardiac sympathetic nerve discharge (SND), electroencephalogram (EEG) activity, phrenic nerve activity, and the R wave of the electrocardiogram were studied with the methods of spike-triggered averaging and postevent interval analysis. Three categories of neurons (SR, SE, and S) with activity patterns related to SND wee identified. The activity of SR units was related in time to SND and the R wave but not to EEG activity. SE unit discharges were related to SND and EEG activity but not to the R wave. S unit activity was related only to SND. Each of the three categories of neurons could be subdivided into two groups depending on whether their discharges were followed by an increase or a decrease in SND. All unit types exhibited respiratory-related discharge patterns. These data are discussed with regard to the problems associated with the identification of neurons in brain stem networks that govern the discharges of sympathetic nerves.

Effects of brain stem lesions on 10-Hz and 2- to 6-Hz rhythms in sympathetic nerve discharge

1992 ◽  
Vol 262 (6) ◽  
pp. R1015-R1024 ◽  
Author(s):  
S. Zhong ◽  
S. M. Barman ◽  
G. L. Gebber
Keyword(s):  
Brain Stem ◽  
Sympathetic Nerve ◽  
Sympathetic Nerves ◽  
Ventrolateral Medulla ◽  
Total Power ◽  
Field Potentials ◽  
Brain Stem Lesions ◽  
Stem Lesions ◽  
Nerve Discharge

We studied the effects of brain stem lesions or transection on the 10-Hz and 2- to 6-Hz rhythms in sympathetic nerve discharge (SND) in baroreceptor-denervated unanesthetized decerebrate cats. The results indicate that these two rhythms depend in part on different brain stem regions. The 10-Hz rhythm was eliminated by ablation of the rostral ventrolateral medulla (RVLM), medullary raphe complex, or pontine parabrachial and Kolliker-Fuse complex (PB/KF) or by pontomedullary border transection. Except for RVLM lesions, these procedures did not disrupt the 2- to 6-Hz rhythm in SND. In fact the power in SND at frequencies less than 6 Hz was increased by raphe or PB/KF lesions. Total power in SND was not significantly affected by raphe or PB/KF lesions, but mean arterial pressure was significantly reduced. Field potentials recorded from the RVLM (11 of 26 sites) and raphe (10 of 20 sites) were correlated to the 10-Hz rhythm in SND, further supporting a role of these areas in either generating or relaying this rhythm to sympathetic nerves. In contrast, field potentials recorded from the PB/KF were not correlated to the 10-Hz rhythm in SND. Thus this region may provide a tonic drive to the 10-Hz generator located elsewhere in the brain stem.

scholarly journals 2019 Ludwig Lecture: Rhythms in sympathetic nerve activity are a key to understanding neural control of the cardiovascular system

2020 ◽  
Vol 318 (2) ◽  
pp. R191-R205 ◽  
Author(s):  
Susan M. Barman
Keyword(s):  
Brain Stem ◽  
Cardiovascular System ◽  
Sympathetic Nerve ◽  
Neural Control ◽  
Sympathetic Nerve Activity ◽  
Cardiovascular Responses ◽  
Sympathetic Nerves ◽  
Ventrolateral Medulla ◽  
Nerve Activity

This review is based on the Carl Ludwig Distinguished Lecture, presented at the 2019 Experimental Biology Meeting in Orlando, FL, and provides a snapshot of >40 years of work done in collaboration with the late Gerard L. Gebber and colleagues to highlight the importance of considering the rhythmic properties of sympathetic nerve activity (SNA) and brain stem neurons when studying the neural control of autonomic regulation. After first providing some basic information about rhythms, I describe the patterns and potential functions of rhythmic activity recorded from sympathetic nerves under various physiological conditions. I review the evidence that these rhythms reflect the properties of central sympathetic neural networks that include neurons in the caudal medullary raphe, caudal ventrolateral medulla, caudal ventrolateral pons, medullary lateral tegmental field, rostral dorsolateral pons, and rostral ventrolateral medulla. The role of these brain stem areas in mediating steady-state and reflex-induced changes in SNA and blood pressure is discussed. Despite the common appearance of rhythms in SNA, these oscillatory characteristics are often ignored; instead, it is common to simply quantify changes in the amount of SNA to make conclusions about the function of the sympathetic nervous system in mediating responses to a variety of stimuli. This review summarizes work that highlights the need to include an assessment of the changes in the frequency components of SNA in evaluating the cardiovascular responses to various manipulations as well as in determining the role of different brain regions in the neural control of the cardiovascular system.

Coherence of medullary unit activity and sympathetic nerve discharge

1990 ◽  
Vol 259 (3) ◽  
pp. R561-R571 ◽  
Author(s):  
G. L. Gebber ◽  
S. M. Barman ◽  
B. Kocsis
Keyword(s):  
Brain Stem ◽  
Unit Activity ◽  
Sympathetic Nerve ◽  
Sympathetic Nerves ◽  
Frequency Domain Analysis ◽  
Ventrolateral Medulla ◽  
Spike Triggered Averaging ◽  
Time Domains ◽  
The Relationship ◽  
Nerve Discharge

Analyses in the frequency and time domains were used to study the relationships between the discharges of single brain stem neurons and postganglionic sympathetic nerves in baroreceptor-innervated and -denervated cats anesthetized with 5,5-diallylbarbiturate-urethan. Spike-triggered averaging was used initially to identify single neurons with sympathetic nerve-related activity in the medullary lateral tegmental field, rostral ventrolateral medulla, and medullary raphe. The discharges of such neurons were correlated to the 2- to 6-Hz rhythm in sympathetic nerve discharge (SND). Frequency-domain analysis revealed that the relationship between medullary unit activity and the sympathetic nerve rhythm was not fixed from cycle to cycle. First, the coherence values relating the activity of these neurons to SND were closer to zero than to unity in most cases. Second, whereas most of the power in the autospectra of SND was contained between 2 and 6 Hz, that in the autospectra of medullary unit activity was more evenly distributed over a much wider frequency band. These and other observations indicate that the 2- to 6-Hz rhythm is an emergent property of a network of brain stem neurons whose discharges are probabilistically rather than strictly related to the phases of the population rhythm.

Sign in / Sign up

Export Citation Format

Share Document