Neurohormonal alteration of integrative properties of the cardiac ganglion of the lobster Homarus americanus

1975 ◽  
Vol 63 (1) ◽  
pp. 33-52
Author(s):  
I. M. Cooke ◽  
D. K. Hartline
Keyword(s):  
Impulse Activity ◽  
Homarus Americanus ◽  
Firing Frequency ◽  
Small Cell ◽  
Small Cells ◽  
Cardiac Ganglion ◽  
Cardiac Ganglia ◽  
Length Increase ◽  
Proximal Site ◽  
Intermediate Value

The spontaneous burst discharges of isolated lobster (Homarus americanus) cardiac ganglia were recorded with a spaced array of electrodes. Small regions (less than 1 mm) of the ganglion were exposed to the cardioexcitor neurohormone in extracts of pericardial organs (XPO) or to 10(−5) M 5-hydroxytryptamine (5HT). All axons were excited (increased mean firing frequency, f) by both substances, but only by applications in the region between the soma (but excluding it) and proximal site of impulse initiation. Units not so exposed changed their f relatively little despite f increases of as much as threefold in exposed units and changes in burst rate and overall length. Regularity and grouping of all impulse activity into bursts was never disturbed. 5HT increases burst rate at any point of application. The increases are larger if small cells are affected than if only large cells are exposed. Burst length decreases except when the pacemaker is affected. In contrast, XPO affects neither burst rate or length unless small cells are affected. Length is increased if non-pacemaker small cells are affected; both rate and length increase if the pacemaker is affected. The pacemaker usually exhibits an f of intermediate value. Rate changes are not simply related to its f. A small cell can “burst” in the absence of impulses from any other cells. XPO may enhance endogenous “driver potentials,” while 5HT may excite by depolarizing at limited sites.

Impulse Identification and Axon Mapping of the Nine Neurons in the Cardiac Ganglion of the Lobster Homarus Americanus

1967 ◽  
Vol 47 (2) ◽  
pp. 327-341
Author(s):  
DANIEL K. HARTLINE
Keyword(s):  
Large Cell ◽  
Homarus Americanus ◽  
Simultaneous Recording ◽  
Small Cell ◽  
Complete Analysis ◽  
Cardiac Ganglion ◽  
Cell Identification ◽  
Cell Axon ◽  
Synaptic Interactions ◽  
Stimulation Of

1. Simultaneous recording from several pairs of electrodes placed along the ganglion and certain efferent nerves, during stimulation of other efferents, allows the course of antidromic impulses in each stimulated axon to be mapped. 2. These impulses disappear as they approach their somata, being incapable of invading them, a fact which permits identification of a particular efferent axon with a particular soma. 3. By these means the courses of all such efferent axons, and their corresponding somata, have been determined. These all belong to the five large cells. 4. The impulses from each such axon occurring during the spontaneous burst can be identified, as can impulses from each small cell. 5. Each large-cell axon appears to be inexcitable until it is a few mm from the soma. 6. If the axon branches within this inexcitable region, the branches tend to fire impulses independently. 7. The technique of cell identification opens the way to a more complete analysis of the ganglion's activity and the synaptic interactions which produce it.

scholarly journals Functional Organization of the Cardiac Ganglion of the Lobster, Homarus americanus

1973 ◽  
Vol 62 (4) ◽  
pp. 448-472 ◽  
Author(s):  
Earl Mayeri
Keyword(s):  
Spike Activity ◽  
Functional Organization ◽  
Large Cell ◽  
Homarus Americanus ◽  
Burst Activity ◽  
Small Cells ◽  
Cardiac Ganglion ◽  
Burst Pattern ◽  
Repetitive Electrical Stimulation ◽  
Stimulation Of

External recording and stimulation, techniques were used to determine which neurons and interactions are essential for production of the periodic burst discharge in the lobster cardiac ganglion. Burst activity can be modulated by brief single shocks applied to the four small cells, but not by similar stimulation of the five large cells, suggesting that normally one or more small cells primarily determine burst rate and duration. Repetitive electrical stimulation of large cells initiates spike activity in small cells, probably via excitatory synaptic and/or electrotonic connections which may normally act to prolong bursts and decrease burst rate. Transection of the ganglion can result in burst activity in small cells in the partial or complete absence of large cell spike activity, but large cells isolated from small cell excitatory synaptic input by transection or by application of dinitrophenol do not burst. Generally, transections which decrease excitatory feedback to small cells are accompanied by an increase in burst rate, but mean spike frequency over an entire burst cycle stabilizes at the original level within 10–30 min for various groups of cells whose spike-initiating sites are still intact. These and previous results suggest that the system is two layered: one or more small cells generate the burst pattern and impose it on the large cells which are the system's motorneurons.

Impulse Activity and Pattern of Large and Small Neurones in the Cardiac Ganglion of the Lobster, Panulirus Japonicus

1973 ◽  
Vol 58 (2) ◽  
pp. 473-486
Author(s):  
KENRO TAZAKI
Keyword(s):  
High Frequency ◽  
Single Unit ◽  
Impulse Activity ◽  
Large Cell ◽  
Small Cells ◽  
Cardiac Ganglion ◽  
Slow Potentials ◽  
Panulirus Japonicus ◽  
Cell Somata ◽  
Frequency Train

1. Single-unit analysis was made by means of internal and external recordings in order to observe the impulse activity of the component neurones in the lobster cardiac ganglion. 2. The large cells fired a brief high-frequency train of postsynaptic impulses in the axonal region by repetitive synaptic activation from small cells which was brought about in the soma-dendritic regions. They generated slow potentials with repetitive impulses by themselves when without synaptic controls. 3. A long-lasting train of presynaptic impulses was propagated from the small pacemaker neurone to the large-cell somata, inducing small synaptic potentials. The burst activity of the ganglion was initiated by this neurone. 4. Impulses of different kinds, presynaptic or postsynaptic, were observed in small cells. This activity occurred at about the same time as that of the pacemaker neurone and was of almost the same duration. 5. Synchronizing mechanisms of all nine neurones were discussed with respect to electrotonic interaction mediated by slow potentials, compared to synaptic interaction mediated by impulses.

scholarly journals Feedback From Motor Neurones to Pacemaker Neurones in Lobster Cardiac Ganglion Contributes to Regulation of Burst Frequency

1989 ◽  
Vol 141 (1) ◽  
pp. 277-294
Author(s):  
A. BERLIND
Keyword(s):  
Average Frequency ◽  
Normal Activity ◽  
Small Cell ◽  
Motor Neurone ◽  
Small Cells ◽  
Layered System ◽  
Cycle Duration ◽  
Cardiac Ganglion ◽  
Burst Frequency ◽  
Motor Neurones

The crustacean cardiac ganglion has traditionally been viewed as a two-layered system in which pacemaking is a function of the four small cells which trigger the five follower motor neurones via chemical and electrotonic synaptic excitation. The work reported here shows that there is strong feedback from motor neurones to small cells, by which endogenous burst-organizing potentials (driver potentials or DPs) and their hyperpolarizing afterpotentials contribute to regulation of bursting frequency. Isolated cardiac ganglia were placed in a two-chamber perfusion system which allowed independent treatment of small cells and motor neurones. When the motor neurones were silenced with tetrodotoxin (TTX), the small cells continued organizing bursts of activity which recurred at an average frequency 41% higher than bursting by normal ganglia in saline. The average burst duration was not altered. Driver potentials were evoked in TTX-treated motor neurones by electrical stimulation, by ionic alteration of the medium, or by treatment with the cardioexcitor peptide proctolin. DPs which occurred synchronously with small-cell bursts prolonged and intensified the bursts (more spikes per burst). When DPs were evoked in motor neurones during the interburst interval, they triggered small-cell bursts even at very short intervals after a spontaneous burst had occurred. All small-cell bursts which were associated with motor neurone DPs were followed by interburst intervals of longer than normal duration. The decrease in instantaneous burst frequency (increase in total burst cycle duration) caused by motor neurone DPs wai similar in magnitude to the drop in burst frequency observed when the ganglion recovered normal activity after TTX washout.

Spontaneous electrical activity and interaction of large and small cells in cardiac ganglion of the crab, Portunus sanguinolentus

1979 ◽  
Vol 42 (4) ◽  
pp. 975-999 ◽  
Author(s):  
K. Tazaki ◽  
I. M. Cooke
Keyword(s):  
Electrical Activity ◽  
Large Cell ◽  
Small Cell ◽  
Small Cells ◽  
Intracellular Recordings ◽  
Cardiac Ganglion ◽  
Main Trunk ◽  
Current Passing ◽  
Spontaneous Electrical Activity ◽  
Slow Depolarization

1. Semi-isolated preparations of the nine-celled cardiac ganglion of the crab, Portunus sanguinolentus, were studied electrophysiologically, using simultaneous recording from extracellular and two or three intracellular electrodes. Nine penetrations of small cells were achieved. 2. Three large (80 x 120 micron) cells lie near the anterior end of the 5-mm main trunk; two large and four small (less than 50 micron) cells at the posterior end. Large-cell axons pass along the main trunk and then exit to innervate cardiac muscle; small-cell axons do not leave the ganglion. 3. The semi-isolated ganglion produces spontaneous electrical activity organized into regularly patterned, rhythmic bursts of large- and small-cell impulses recurring at rates of 0.3-0.6/s and lasting 500-800 ms. Small impulse activity commences and ends each burst. Small cells fire trains during the burst, but impulses are not synchronized among them. Large-cell trains are synchronous, are at about one-half the frequency, and have fewer impulses than small-cell trains. 4. Intracellular recordings from small cells show a slow, pacemaker depolarization from a maximum membrane potential of -54 mV leading with only a slight inflection at ca. -50 mV to a depolarized plateau at ca. -40 mV; nonovershooting impulses are superimposed on this but cease before it repolarizes. Impulses, therefore, arise at a site distant from the soma and do not invade it. Deflections suggesting synaptic potentials are not seen. 5. Intracellular recordings from large cells show complex depolarizations corresponding to extracellularly recorded bursts. These represent excitatory postsynaptic potentials (EPSPs) corresponding with individual small-cell impulses, attenuated, non-overshooting spikes, and an underlying slow depolarization; usually no pacemaker depolarization is apparent between bursts. Chemically mediated transmission is probable for the EPSPs because they show delay, increase in amplitude with hyperpolarization, sometimes show facilitation, and are reduced in saline having one-third Ca, 3 x Mg. 6. EPSPs, impulses, and the slow depolarization occur synchronously among the large cells. Potentials recorded from posterior cells are attenuated and slower than those of the anterior cells. This is interpreted to reflect sites of occurrence more distant from the soma in the posterior than in the anterior cells. Impulses do not invade the somata. 7. Intracellular recordings from large-cell axons 4 mm from the soma show overshooting action potentials arising sharply from a base line. EPSPs are absent or highly attenuated and there is little underlying depolarization (less than 2 mV). 8. Current passing with electrodes intracellular to two cells has established directly that all large cells are electrotonically coupled and that an anterior cell and a small cell are coupled. Changes of burst rate during current passing into any large cell indicate that all large cells and small cells are electrotonically coupled. 9...

scholarly journals A Relaxation Oscillator Description of the Burst-Generating Mechanism in the Cardiac Ganglion of the Lobster, Homarus americanus

1973 ◽  
Vol 62 (4) ◽  
pp. 473-488 ◽  
Author(s):  
Earl Mayeri
Keyword(s):  
Silent Period ◽  
Relaxation Oscillator ◽  
Neural Mechanism ◽  
Homarus Americanus ◽  
Small Cells ◽  
Cardiac Ganglia ◽  
Burst Period ◽  
Early Portion ◽  
Linear Differential ◽  
Ganglion Neurons

Properties of the neural mechanism responsible for generating the periodic burst of spike potentials in the nine ganglion neurons were investigated by applying brief, single shocks to the four small cells with extracellular electrodes placed near the trigger zones of the small cells. The shock elicited a burst if presented during the latter portion of the silent period, terminated a burst during the latter portion of the burst period, and was followed by a newly initiated burst during the early portion of the burst period. The resultant changes in burst and silent period durations were quantitatively described by a second-order non-linear differential equation similar to the van der Pol equation for a relaxation oscillator. The equation also qualitatively described changes in firing threshold of the small cells during the burst cycle. The first derivative of the solution to the equation is similar to slow transmembrane potentials in neurons that are involved in generation of burst activity in other crustacean cardiac ganglia.

scholarly journals A Comparative Analysis of Wi-Fi Offloading and Cooperation in Small-Cell Network

Electronics ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 1493
Author(s):  
Ayesha Ayub ◽  
Sobia Jangsher ◽  
M. Majid Butt ◽  
Abdur Rahman Maud ◽  
Farrukh A. Bhatti
Keyword(s):  
Small Cell ◽  
Base Stations ◽  
Small Cells ◽  
Effective Capacity ◽  
Rate Enhancement ◽  
Cell Network ◽  
Small Cell Network ◽  
User Throughput ◽  
Average User ◽  
Cell Cooperation

Small cells deliver cost-effective capacity and coverage enhancement in a cellular network. In this work, we present the interplay of two technologies, namely Wi-Fi offloading and small-cell cooperation that help in achieving this goal. Both these technologies are also being considered for 5G and B5G (Beyond 5G). We simultaneously consider Wi-Fi offloading and small-cell cooperation to maximize average user throughput in the small-cell network. We propose two heuristic methods, namely Sequential Cooperative Rate Enhancement (SCRE) and Sequential Offloading Rate Enhancement (SORE) to demonstrate cooperation and Wi-Fi offloading, respectively. SCRE is based on cooperative communication in which a user data rate requirement is satisfied through association with multiple small-cell base stations (SBSs). However, SORE is based on Wi-Fi offloading, in which users are offloaded to the nearest Wi-Fi Access Point and use its leftover capacity when they are unable to satisfy their rate constraint from a single SBS. Moreover, we propose an algorithm to switch between the two schemes (cooperation and Wi-Fi offloading) to ensure maximum average user throughput in the network. This is called the Switching between Cooperation and Offloading (SCO) algorithm and it switches depending upon the network conditions. We analyze these algorithms under varying requirements of rate threshold, number of resource blocks and user density in the network. The results indicate that SCRE is more beneficial for a sparse network where it also delivers relatively higher average data rates to cell-edge users. On the other hand, SORE is more advantageous in a dense network provided sufficient leftover Wi-Fi capacity is available and more users are present in the Wi-Fi coverage area.

Nervous control of the heartbeat in octopus

1980 ◽  
Vol 85 (1) ◽  
pp. 111-128 ◽  
Author(s):  
M. J. Wells
Keyword(s):  
Circulatory System ◽  
Aortic Pressure ◽  
Surgical Removal ◽  
Cardiac Ganglion ◽  
Nervous Control ◽  
Cardiac Ganglia ◽  
Before And After ◽  
Branchial Heart ◽  
Systemic Heart

The circulatory system of cephalopods is based on a trio of hearts, with two pairs of associated ganglia linked to the CNS by a pair of visceral nerves. The beat of the hearts was recorded from free-moving octopuses before and after surgical removal or disconnexion of elements of the nervous system. Severing the visceral nerves does not stop the hearts, which continue to beat in a powerful well co-ordinated manner in isolation from the CNS. The nerves seem to be concerned in raising the cardiac output in exercise, and with stopping the hearts when mantle movements cease, but they are not necessary for the initiation of maintenance of the normal rhythm. Removal of the fusiform ganglia severs all nervous connexions between the ywo gill hearts, and deprives the systemic heart of its nerve supply. The trio of hearts continues to beat as strongly as before. Removal or disconnexion of a cardiac ganglion disrupts the beat of the corresponding gill heart which now tends to contract in an ill-coordinated and rather feeble manner, though at much the same frequency as before; with both cardiacs gone the systemic heart, which contracts only when it is filled, tends to drop in frequency and the mean aortic pressure falls. The system remains rhythmic, however, and the beat may recover, to the point where aortic pressures and frequencies approach those found in intact animals at rest; even octopuses with both fusiform and both cardiac ganglia removed can survive for many hours. From the performance of the isolated branchial heart, the existence of a pulsating vesicle in each cardiac ganglion, the effects of cardiac ganglion removal and the remarkable steadiness of heartbeat frequency shown by intact animals under a variety of conditions, it is argued that the heartbeat rhythm is normally controlled by pacemakers in the branchial heart/ cardiac ganglion complexes, and perhaps, in intact animals, from within the cardiac ganglia themselves. The picture of the control of the heartbeat that emerges from the study of free moving essentially intact animals is quite different from that arising from in vitro and acute preparation studies. It suggests that the conventional wisdom about the control of the heartbeat in cephalopods (and perhaps by implication, in other molluscs) may need to be considerably revised.

Network Throughput and Outage Analysis in a Poisson and Matérn Cluster based LTE-Advanced Small Cell Networks

2021 ◽  
Author(s):  
Joydev Ghosh
Keyword(s):  
Outage Probability ◽  
Cell Formation ◽  
Access Network ◽  
Small Cell ◽  
Network Throughput ◽  
Base Stations ◽  
Small Cells ◽  
Network Cell ◽  
Lte Advanced ◽  
The Impact

<div>In LTE-A (LTE-Advanced), the access network cell formation is an integrated form of outdoor unit and indoor unit. With the indoor unit extension the access network becomes heterogeneous (HetNet). HetNet is a straightforward way to provide quality of service (QoS) in terms better network coverage and high data rate. Although, due to uncoordinated, densely deployed small cells large interference may occur, particularly in case of operating small cells within the spectrum of macro base stations (MBS). This paper probes the impact of small cell on the outage probability and the average network throughput enhancement. The positions of the small cells are retained random and modelled with homogeneous Poisson Point Process (PPP) and Matérn Cluster process (MCP). The paper provides an analytic form which permits to compute the outage probability, including the mostly applied fast fading channel types. Furthermore, simulations are evaluated in order to calculate the average network throughput for both random processes. Simulation results highlights that the network throughput remarkably grows due to small cell deployment.</div>

Neurotransmission in neonatal rat cardiac ganglion in situ

1990 ◽  
Vol 259 (4) ◽  
pp. H997-H1005 ◽  
Author(s):  
G. R. Seabrook ◽  
L. A. Fieber ◽  
D. J. Adams
Keyword(s):  
Neuronal Cell ◽  
Nerve Fibers ◽  
Heart Beat ◽  
Neonatal Rat ◽  
Neuronal Cell Body ◽  
High Frequency Stimulation ◽  
Excitatory Postsynaptic Potential ◽  
Cardiac Ganglion ◽  
Cardiac Ganglia

The intrinsic cardiac ganglia of the neonatal rat heart in situ were studied using electrophysiological and histochemical techniques. The vagal branches innervating the atrial myocardium and cardiac ganglia were identified and individual ganglion cells visualized using Hoffman modulation contrast optics. Histochemical studies revealed the presence of acetylcholinesterase activity associated with neuronal cell bodies and fibers, catecholamine-containing, small intensely fluorescent cells, and cell bodies and nerve fibers immunoreactive for vasoactive intestinal polypeptide. Intracellular recordings from the "principal" cells of the rat cardiac ganglion in situ revealed a fast excitatory postsynaptic potential (EPSP) evoked after electrical stimulation of the vagus nerve, which was inhibited by the nicotinic receptor antagonist, mecamylamine. No spontaneously firing neurons were found, although infrequent (less than 2 min-1) spontaneous miniature EPSPs were observed in most neurons. The quantal content of neurally evoked responses was between 10 and 30 quanta, and the presence of multiple EPSPs in some cells suggested polyneuronal innervation. The neurally evoked EPSP amplitude was dependent on the rate of nerve stimulation, decreasing with increasing frequency of stimulation. Neurons exhibited a sustained depolarization during high frequency stimulation (greater than 1 Hz), and in approximately 15% of the cells a slow depolarization lasting 1-3 min was observed after a train of stimuli. The presence of catecholamine- and neuropeptide-containing neuronal cell body fibers in neonatal rat cardiac ganglia in situ, along with neurally evoked postsynaptic responses resistant to cholinergic ganglionic blockers, suggests a role for noncholinergic transmission in the regulation of the mammalian heart beat.

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