Journal Article•
Impulse identification and axon mapping of the nine neurons in the cardiac ganglion of the lobster Homarus americanus.
01 Oct 1967-The Journal of Experimental Biology (The Company of Biologists Ltd)-Vol. 47, Iss: 2, pp 327-341
TL;DR: The technique of cell identification opens the way to a more complete analysis of the ganglion9s activity and the synaptic interactions which produce it.
Abstract: 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 ganglion9s activity and the synaptic interactions which produce it.
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TL;DR: Describing of six behaviors of leech behavior including their origins within neuronal circuits, their modification by feedback loops and neuromodulators, and interactions between circuits underlying with these behaviors are provided.
362 citations
Cites background from "Impulse identification and axon map..."
...Finally, research on the cardiac ganglion and stomatogastric systems in lobster (Hartline, 1967; Mulloney and Selverston, 1974), leech swimming (Kristan and Calabrese, 1976), and lamprey swimming (Cohen and Wallén, 1980), as well as numerous additional preparations (Selverston, 1985; Marder and…...
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TL;DR: This review will discuss how principles from theoretical principles arising from studies of the properties of interneurons within the CNS apply to locomotion and will suggest that they may also serve as useful working hypotheses in the study of other motor systems.
Abstract: The central nervous system (CNS) must produce specific patterns of motor neuron impulses during a coordinated movement. The desire to understand how these patterns are produced and controlled has led investigators to examine the properties of interneurons within the CNS. A set of theoretical principles has emerged from these studies that are applicable to both invertebrates and vertebrates (Wilson 1967, Evarts et al 1971, Gurfinkel & Shik 1973, R. B. Stein et al 1973, Grillner 1975, Herman et al 1976, Shik&Orlovsky 1976, Wetzel & Stuart 1976, P. S. G. Stein 1977). This review will discuss how these principles apply to locomotion and will demon strate that they may also serve as useful working hypotheses in the study of other motor systems. The central hypothesis is that there is a neural pattern generator residing within the CNS that serves to produce the basic motor program (Wilson 1972). Informa tion derived from sensory input may modify the output of the pattern generator so that the motor output is adapted to the particular mechanical properties of the organism and its environment. The principles are the following:
241 citations
01 Jan 1977
224 citations
Cites background from "Impulse identification and axon map..."
...This has been well established in the case of the crustacean cardiac ganglion (Hagiwara, 1961; Hartline, 1967; Watanabe et ai., 1967)....
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TL;DR: The continuing relevance of the crustacean cardiac ganglion as a relatively simple model for pacemaking and central pattern generation is confirmed by the rapidly widening documentation of intrinsic potentials such as plateau potentials in neurons of all major animal groups.
Abstract: Investigations of the electrophysiology of crustacean cardiac ganglia over the last half-century are reviewed for their contributions to elucidating the cellular mechanisms and interactions by which a small (as few as nine cells) neuronal network accomplishes extremely reliable, rhythmical, patterned activation of muscular activity-in this case, beating of the neurogenic heart. This ganglion is thus a model for pacemaking and central pattern generation. Favorable anatomy has permitted voltage- and space-clamp analyses of voltage-dependent ionic currents that endow each neuron with the intrinsic ability to respond with rhythmical, patterned impulse activity to nonpatterned stimulation. The crustacean soma and initial axon segment do not support impulse generation but integrate input from stretch-sensitive dendrites and electrotonic and chemically mediated synapses on axonal processes in neuropils. The soma and initial axon produce a depolarization-activated, calcium-mediated, sustained potential, the "driver potential," so-called because it drives a train of impulses at the "trigger zone" of the axon. Extreme reliability results from redundancy and the electrotonic coupling and synaptic interaction among all the neurons. Complex modulation by central nervous system inputs and by neurohormones to adjust heart pumping to physiological demands has long been demonstrated, but much remains to be learned about the cellular and molecular mechanisms of action. The continuing relevance of the crustacean cardiac ganglion as a relatively simple model for pacemaking and central pattern generation is confirmed by the rapidly widening documentation of intrinsic potentials such as plateau potentials in neurons of all major animal groups. The suite of ionic currents (a slowly inactivating calcium current and various potassium currents, with variations) observed for the crustacean cardiac ganglion have been implicated in or proven to underlie a majority of the intrinsic potentials of neurons involved in pattern generation.
131 citations
Cites background or methods from "Impulse identification and axon map..."
...1A), contractions of the quiescent heart muscle can be elicited by probing sites in which CG dendrites are embedded (Alexandrowicz, 1932; Cooke, 1962; Hartline, 1967)....
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...Further confirmation of the consistency of burst patterning came with analysis of the patterning by Hartline (1967), who used an array of five or more pairs of extracellular electrodes placed along the trunk and major nerves of the Homarus ganglion to identify each impulse with its axon by mapping…...
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...In Homarus, the first 3 to 4 impulses of large-cell axons occur at high frequency (90–120/s) and then continue for 3 or more at a slower rate (10–20/s, Hartline, 1967); small-cell axons fire as many as 15 impulses starting at rates of 80/s and declining during the burst toward 20–30/s....
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...Electrophysiological monitoring of the CG confirmed the absence of activity in the quiescent Homarus heart (Hartline, 1967)....
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TL;DR: The correlations in the LCs of the crab cardiac ganglion are different from those in STG neurons, supporting the idea that such correlations could be markers of cell identity or activity.
Abstract: Background: To what extent do identified neurons from different animals vary in their expression of ion channel genes? In neurons of the same type, is ion channel expression highly variable and/or is there any relationship between ion channel expression that is conserved? Methodology/Principal Findings: To address these questions we measured ion channel mRNA in large cells (LCs) of the crab cardiac ganglion. We cloned a calcium channel, caco, and a potassium channel, shaker. Using single-cell quantitative PCR, we measured levels of mRNA for these and 6 other different ion channels in cardiac ganglion LCs. Across the population of LCs we measured 3–9 fold ranges of mRNA levels, and we found correlations in the expression of many pairs of conductances Conclusions/Significance: In previous measurements from the crab stomatogastric ganglion (STG), ion channel expression was variable, but many pairs of channels had correlated expression. However, each STG cell type had a unique combination of ion channel correlations. Our findings from the crab cardiac ganglion are similar, but the correlations in the LCs are different from those in STG neurons, supporting the idea that such correlations could be markers of cell identity or activity.
107 citations
Cites background from "Impulse identification and axon map..."
...consists of five large cell (LC) motor neurons and four small pacemaker cells, all of which are electrically coupled and burst synchronously to drive the contraction of the heart muscle [22–26] (Fig....
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References
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TL;DR: In the heart of the Decapod Crustacea three systems of nervous elements can be distinguished, viz. a local system of neurons which are distributed in the heart itself, a system of fibres connecting the heart with the central nervous system, and a network of nerves which supply the valves of the arteries arising from the heart as well as the muscles of the pericardium.
Abstract: The results of our investigations may be summarized as follows: (1) In the heart of the Decapod Crustacea three systems of nervous elements can be distinguished, viz. ( a ) a local system of neurons which are distributed in the heart itself; ( b ) a system of fibres connecting the heart with the central nervous system; and ( c ) a system of nerves which supply the valves of the arteries arising from the heart as well as the muscles of the pericardium. (2) The local nervous system consists of a nervous trunk situated in the dorsal wall of the heart near to its inner surface from which branches to the muscle-fibres of the heart are distributed. The main trunk is generally called the ganglionic trunk from the presence of nerve-cells in it. The cells are of two kinds: large and small. Their number was found to be constant, and comprises in Cancer pagurus, Maia squinado, and Homarus vulgaris--the species which could be best investigated as to this point--nine elements., viz. five large and four small cells. It seems that in other species of marine Decapods the number of cells in the hearts, if not the same, does not at any rate vary much. Potamobius, however, has not less than sixteen elements (eight large, and eight, maybe, nine or ten, small ones). The cells are multipolar in shape. Their long processes--the axons--after sending out shorter ramifications run in regular courses, giving off long branches to all the muscles of the heart including those of the ostia, but excluding the muscle-fibres of the arterial valves. The short processes, which I regard as dendrites, spring from the cell-bodies and from the proximal parts of the axons. The endings of the dendrites which ramify in the muscle-bundles differ in appearance from the terminations of the long branches springing from the axons. The small cells possess similar processes, i.e. dendrites and axons. The latter could not be traced well. In the main or ganglionic trunk which in different species has different shapes, the following elements are present: ( a ) large and small cells, the arrangement of which varies in different species, but in all cases the small cells are situated in the posterior part of the trunk; ( b ) the axons of the large and small cells and a part of their branches; ( c ) the fibres of the dorsal nerves; ( d ) the neuropile-like networks of fibrils where the synapses between the efferent fibres and the neurons of the local system take place. These neuropiles form several more compact masses in Brachyura whilst in Macrura they are more diffusely scattered in the ganglionic trunk. (3) The fibres connecting the heart with the central nervous system take their origin in the infra-oesophageal ganglion and travel in the nerves running on the thoracic muscles. As separate bundles, one on each side, they turn towards the dorsal surface of the heart; hence the term nervi cardiaci dorsales is proposed; the other term--regulator nerves--indicates their physiological character. In their further course these nerves pierce the heart-wall and reach the local nervous system. The fibres of the dorsal nerves are of various diameters. The thicker, which in the description have been called System I, run throughout the ganglionic trunk and break up therein in many richly arborizing branches which at many places resemble in appearance the neuropile-like networks of fibrils. They are the fields of conjunction of all the fibres of System I with each other, as well as with the neurons of the local system. From the latter the following parts are in close relation with the fibrils of System I: ( a ) the collaterals of the axons entering the neuropile; ( b ) the dendrites; ( c ) the cell-bodies surrounded by a network of fibrils of the dorsal nerves; these basketworks, however, could not be seen in all the species investigated, and occur on the large cells only. Some branches of System I were found leaving the ganglionic trunk, but their destination is uncertain. The remaining fibres of the dorsal nerves which, it may be assumed, do not belong to the System I are of smaller but not equal diameter. Some take their course to the muscles without entering the ganglionic trunk, others travel in the latter, but their distribution could not be made out. (4) The third system of nerves, which enter into relationship with the heart by innervating the valves situated at the origin of the main arterial trunks, contains the following elements: ( a ) Nervi segmentales cord is, which number, as was found in Astacus, four on each side, branch from the thoracic nerves and pass on the ventral side of the pericardium towards the middle line. Here they join into--according to the species--one or two bundles, which take a longitudinal course. From these bundles branches are given off to the valves of five arteries, viz. arteriae antennales, arteriae hepaticae, and aorta posterior, and to the muscles of the ventral pericardial plate. The latter receive also branches springing directly from the segmental nerves. The system of the segmental nerves of the heart is connected with the nerves of the dorsal abdominal artery which in its turn receives segmental nerves originating in the abdominal ganglia and ending in the valves of the arteries arising from the vessel named. ( b ) The nervus cardiacus anterior arises from the stomatogastric nerve and runs alongside the median anterior artery. The territory of the terminal branches of this nerve, known as ‘nerf cardiaque’ of Lemoine, has been found to be confined entirely to the valve of the median anterior vessel (aorta anterior s. arteria ophthalmica). No connexion with the nerves of other valves could be ascertained. (5) Besides the three nervous systems enumerated which are in relation with the heart itself, several nerve branches running from the thoracic nerves penetrate the pericardial cavity. They break up here in the neuropile-like networks situated on the so-called ligaments of the heart and on the connective tissue covering the dorsal wall of the heart. (6) The probable function of all these elements is thought to be as follows: The local system is an ‘autonomic’ nervous apparatus from which the muscles of the heart receive impulses necessary for their regular contractions. The fact that the dendrites of the cells end in the muscles suggests that the rhythmical discharges in the nerve-cells are under the influence of the rhythmical action of the muscles. Thus, there may be secured a reciprocal regulation of the process in two parts of the neuromuscular apparatus of the heart. The dorsal nerves convey to the heart the inhibitory and accelerator fibres. Some evidence seems to indicate that the thicker fibres which have been found giving synapses with the neurons of the local system are endowed with the inhibitory function. The nerves of the arterial valves may be considered as carrying impulses which hold the muscle-fibres in contraction during the diastolic period of the heart. The nerves in the pericardial cavity, ending in fine networks, have evidently some sensory function.
156 citations
"Impulse identification and axon map..." refers background or result in this paper
...The somata of these cells are located in the posterior trunk (Alexandrowicz, 1932), yet one and usually two small-cell impulses have trigger zones in the anterior trunk, and at least one impulse is normally excluded completely from the posterior trunk....
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...As they travel anteriorly they split at the bifurcation in agreement with the histological evidence of Alexandrowicz (1932), but they are of decreasing size as they proceed into the lateral trunks and disappear at about the levels of the somata of Cells 1 and 2....
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...The four small-cell somata are spaced along the posterior trunk (Alexandrowicz, 1932)....
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...As they progress peripherally, the posterolateral and anterolatera nerves communicate via the lateral commissures (Lat.comm.) which are probably homologous to the 'circular trunks' described by Alexandrowicz (1932) in Cancer....
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...Histological observations by Alexandrowicz (1932) indicate three processes arising from the cell, one in each branch of the ganglion....
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TL;DR: The pattern of nervous activity in a spontaneously active nerve center containing only nine neurons, the cardiac ganglion of the lobster, is described, which is a burst of large and small nerve impulses, each neuron firing several times during the burst, followed by a lengthy silent period.
Abstract: 1. The pattern of nervous activity in a spontaneously active nerve center containing only nine neurons, the cardiac ganglion of the lobster, is described. This pattern is a burst of large and small nerve impulses, each neuron firing several times during the burst, followed by a lengthy silent period.2. When isolated, single large neurons tend to fire spontaneously at a constant frequency several times greater than normal burst frequency. It is suggested that the rhythmic burst derives from such spontaneity by a reciprocal interaction among the ganglion units which produces alternating periods of high synaptic excitation and post-excitatory depression.3. Large, rapidly conducted impulses originating in the five large ganglion cells cause the rapid contraction of the heart muscle. Smaller, slower impulses arising in the four small ganglion cells produce no noticeable motor response, but increase activity in the large neurons. Both large and small cells seem to function as pacemakers, interneurons, and possi...
113 citations
"Impulse identification and axon map..." refers background in this paper
...…sufficient patience most of the occurrences of most of the units can be identified in each burst using two additional observations (first noted by Maynard, 1955): first, firing in each unit tends to be fairly regular, steadily declining from a high frequency at the beginning of the burst;…...
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...On the basis of their region of origin and direction of propagation, Maynard (1955) identified the large rapidly propagating impulses seen during the burst with the large cells and the small slowly propagating ones with the small cells....
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TL;DR: All inorganic perfusing solution for the heart of the lobster Homarus americanus, to allow prolonged normal beating (20 hours or more) must agree closely with the inorganic composition of the serum, which varies differentially with that of the environmental sea water.
Abstract: 1. All inorganic perfusing solution for the heart of the lobster Homarus americanus, to allow prolonged normal beating (20 hours or more) must agree closely with the inorganic composition of the serum, which varies differentially with that of the environmental sea water. 2. All of the chief inorganic ions of the serum are necessary—Na, K, Ca, Mg, Cl, and SO4; the critical numbers of the ions being 100, 3, 5, 2–3, 116, and 1–2 respectively. Absence of Mg and SO4 will be tolerated for several hours. 3. The pH of the solution must agree with that of the serum within 0.2. 4. The osmotic pressure of the solution must agree with that of the serum within 15 per cent. 5. Beating of the heart will continue for several hours on improperly balanced solutions but changes in frequency, tone, or amplitude will occur. Hearts adapted to such solutions will show different responses to physical and chemical stimuli of the solution than those perfused on properly balanced solutions. 6. Arrest in systole is caused by isotonic NaCl, KCl, LiCl, and urea, and arrest in diastole by isotonic CaCl2, MgCl2, NaBr, NaI, MgSO4, and glucose. 7. Lithium cannot replace sodium; neither can bromide or iodide replace chloride ions.
109 citations
"Impulse identification and axon map..." refers methods in this paper
...It was pinned ventral side up in a dish of perfusion fluid (Cole, 1941), the ventral wall was slit longitudinally, and the sides were pinned out exposing the ganglion, which adheres to the inside of the postero-dorsal wall....
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01 Jan 1961
TL;DR: Findings show that the cardiac rhythm arises not only at the cardiac ganglion but also at certain neurons in the ganglions.
Abstract: Crustacean cardiac rhythms, unlike those of vertebrates, do not originate in the heart muscle itself. Ganglion cells are normally located in the dorsal wall of the heart and the excitation for the heart beat starts at the ganglion. A neurogenic origin of the heart beat, however, was first demonstrated in Limulus by Carlson (1904). He applied a warm test tube on various parts of the heart muscle and ganglion and found that the cardiac rhythm was accelerated only when the tube was placed on a certain part of the ganglion (the fourth and fifth segments of the ganglion). If the ganglion was removed from the heart the beat stopped. These findings show that the cardiac rhythm arises not only at the cardiac ganglion but also at certain neurons in the ganglion.
81 citations