Electrical properties of the pacemaker neurons in the heart ganglion of a stomatopod, Squilla oratoria.
01 Mar 1967-The Journal of General Physiology (The Rockefeller University Press)-Vol. 50, Iss: 4, pp 813-838
TL;DR: Comparison with action potentials caused by axonal stimulation and analysis of time relations indicate that with stronger currents the soma membrane is directly stimulated whereas with weaker currents the impulse first arises in the axon and then invades the Soma.
Abstract: In the Squilla heart ganglion, the pacemaker is located in the rostral group of cells. After spontaneous firing ceased, the electrophysiological properties of these cells were examined with intracellular electrodes. Cells respond to electrical stimuli with all-or-none action potentials. Direct stimulation by strong currents decreases the size of action potentials. Comparison with action potentials caused by axonal stimulation and analysis of time relations indicate that with stronger currents the soma membrane is directly stimulated whereas with weaker currents the impulse first arises in the axon and then invades the soma. Spikes evoked in a neuron spread into all other neurons. Adjacent cells are interconnected by electrotonic connections. Histologically axons are tied with the side-junction. B spikes of adjacent cells are blocked simultaneously by hyperpolarization or by repetitive stimulation. Experiments show that under such circumstances the B spike is not directly elicited from the A spike but is evoked by invasion of an impulse or electrotonic potential from adjacent cells. On rostral stimulation a small prepotential precedes the main spike. It is interpreted as an action potential from dendrites.
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01 Mar 1974-Journal of Comparative Physiology A-neuroethology Sensory Neural and Behavioral Physiology
TL;DR: The Stomatogastric ganglion of Panulirus interruptus contains about 30 neurons, and controls the movements of the lobster's stomach, and a group of six neurons which drive the stomach's lateral teeth are described.
Abstract: The Stomatogastric ganglion ofPanulirus interruptus contains about 30 neurons, and controls the movements of the lobster's stomach When experimentally isolated, the ganglion continues to generate complex rhythmic patterns of activity in its motor neurons which are similar to those seen in intact animals
275 citations
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 from "Electrical properties of the pacema..."
...…first discussed as an intrinsic potential by Watanabe (1958) in lobster CG, and further described in studies of the Squilla (stomatopod) CG (Watanabe et al., 1967a, b), driver potentials are relatively slow, sustained, regenerative depolarizations that may arise from a gradual pacemaker…...
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...…the DP) with attenuated sharp deflections that are synchronous with the overshooting impulses arising from a flat baseline recorded from the axon (Watanabe et al., 1967b, Squilla oratorio; Tazaki, 1970, Eriocheir japonicus; Tazaki, 1973, Panulirus japonicus; Tazaki and Cooke, 1983a, Portunus…...
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...Such appositions have also been described in CG of Panulirus (Ohsawa, 1972) and Squilla (Irisawa and Hama, 1965; Watanabe et al., 1967a)....
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...(Watanabe et al., 1967a, fig....
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...6A) (Watanabe and Bullock, 1960; Watanabe et al., 1967b, in Squilla; Tazaki, 1972, in Eriocheir; Mayeri, 1973a, b, in Homarus; Matsui et al., 1977, in Panulirus; Tazaki and Cooke, 1979a, and Benson, 1980, in Portunus)....
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TL;DR: The sections in this article are: Anatomic Organization, Reflex Organization, Central Organization of Motor Systems, and Complex Behavioral Phenomena.
Abstract: The sections in this article are:
1
Properties of Muscle
11
Anatomic Organization
12
Contraction Speed
13
Strength and Extent of Contraction
14
Thresholds for Excitation-Contraction Coupling
15
Correlations with Innervation
16
Dependence of Tension on Recent History
2
Motor Neurons and the Motor Unit
21
Motor Neuron Morphology
22
Correlations Between Motor Neuron Morphology and Function
23
Neuromuscular Transmission
24
Excitation-Contraction Coupling
25
Peripheral Motor Unit Organization
26
Matching of Central and Peripheral Properties
27
Ontogeny and Regeneration
3
Reflex Organization
31
Proprioceptive Reflexes
32
Exteroreceptive Reflexes
33
Righting Reflexes
34
Optomotor Reflexes
35
Control of Reflex Excitability
4
Central Organization of Motor Systems
41
Structure of Motor Programs
42
Storage of Motor Programs
43
Release of Motor Programs by Command Elements
44
Central Versus Peripheral Control of Motor Output
45
Development of Pattern-Generating Networks
46
Complex Behavioral Phenomena
5
Conclusion
97 citations
TL;DR: From somata of the pacemaker neurons in the Squilla heart ganglion, pacemaker potentials for the spontaneous periodic burst discharge are recorded with intracellular electrodes, showing that it is an electrically excitable response.
Abstract: From somata of the pacemaker neurons in the Squilla heart ganglion, pacemaker potentials for the spontaneous periodic burst discharge are recorded with intracellular electrodes. The electrical activity is composed of slow potentials and superimposed spikes, and is divided into four types, which are: (a) "mammalian heart" type, (b) "slow generator" type, (c) "slow grower" type, and (d) "slow deficient" type. Since axons which are far from the somata do not produce slow potentials, the soma and dendrites must be where the slow potentials are generated. Hyperpolarization impedes generation of the slow potential, showing that it is an electrically excitable response. Membrane impedance increases on depolarization. Brief hyperpolarizing current can abolish the plateau but brief tetanic inhibitory fiber stimulation is more effective for the abolition. A single stimulus to the axon evokes the slow potential when the stimulus is applied some time after a previous burst. Repetitive stimuli to the axon are more effective in eliciting the slow potential, but the depolarization is not maintained on continuous stimulation. Synchronization of the slow potential among neurons is achieved by: (a) the electrotonic connections, with periodic change in resistance of the soma membrane, (b) active spread of the slow potential, and (c) synchronization through spikes.
78 citations
Cites background or result from "Electrical properties of the pacema..."
..., · ~ ceding paper (Watanabe et al., 1967)....
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...The electrotonic isolation of the parallel axons from the soma is consistent with the histological finding (Watanabe et al., 1967), which indicates that the proximal part of the axon does not form side-junctions with the parallel axons....
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...The ratio is about 1.3, which is certainly out of the range of the attenuation ratios observed in resting cells (Watanabe et al., 1967)....
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...3, which is certainly out of the range of the attenuation ratios observed in resting cells (Watanabe et al., 1967)....
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...On the other hand, it is known that the cell somata are electrotonically connected with each other across a distance of several millimeters (Watanabe et al., 1967), and the spontaneous slow potential spreads from one cell to another (Fig....
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TL;DR: The overall view is of a two-layered neural system in which the small cells possess an endogenous oscillatory driver potential, synchronized by synaptic and electrotonic interac?
Abstract: synopsis. The synchronized bursts of impulses produced by the nine neurons of the isolated Homarus cardiac ganglion are usually initiated by Cell 7. Activity in all other cells commences with very short latency thereafter. Impulses in most cells originate in trigger zones located 1-2 mm from the cell body, but the first several impulses in Cells 8 and 9 frequently originate in distal trigger zones some distance from the somata. Large cells fire at a high initial frequency, dropping rapidly to a low frequency plateau. Small cells exhibit a more tonic behavior and fire at intermediate rates. More anterior small cells tend to fire faster than more posterior ones. The major synaptic interactions are the impulse-mediated excitatory ones from small cells to large cells, and possibly to more anterior small cells. There are weak interactions from large cells back onto small cells, and very specific interactions from Cells 1 and 2 onto 3A, 4A, 5A, and 3B, 4B, 5B respectively. The large discrete EPSPs generated in large cells by small cell impulses appear to be the explanation for "discrete positioning" in large-cell firing patterns. In this situation, large-cell impulses only fire at discrete times during the burst, regardless of the actual large-cell pattern. The overall view is of a two-layered neural system in which the small cells possess an endogenous oscillatory driver potential, synchronized by synaptic and electrotonic interac? tions, and driving a train of impulses in each cell. This activates excitatory synapses on the large cells, which combined with a triggered driver potential in each large cell, produces synchronized trains of motor impulses which activate the heart muscle, causing the heart? beat.
68 citations
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75 citations
"Electrical properties of the pacema..." refers background in this paper
...It is supposed that the apposed parts form an ephaptic junction between neurons and allow the conduction of spikes in either direction (Kao and Grundfest, 1957; Watanabe and Grundfest, 1961; Bennett, Aljure, Nakajima, and Pappas, 1963)....
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TL;DR: The squid giant axon's membrane potential is investigated using internal longitudinal stimulating and recording electrodes and it is concluded that the critical depolarization is a certain potential level at which the dV/dt immediately following changes its sign and is often followed by a plateau potential which represents an unstable equilibrium potential level.
Abstract: (1) The potential change across the membrane of the squid giant axon during passage of electric current is investigated using internal longitudinal stimulating and recording electrodes.(2) The threshold condition for constant current pulse is determined by the electrical constants of the resting membrane when the duration of pulse is short (less than 2 msec. at about 16°C.). For longer currents, up to 5 msec.(at about 16°C.), some amount of subthreshold potential change contributes to the condition. In both cases the critical depolarization for the spike shows the same value which is called the resting critical depolarization.(3) Shifting the membrane potential to various levels with short current pulses it is concluded that the critical depolarization is a certain potential level at which the dV/dt immediately following changes its sign and is often followed by a plateau potential which represents an unstable equilibrium potential level.(4) The minimal gradient for stimulation with a linearly increasing current is mainly determined by delayed rectification of the membrane while the late phase of accommodation is due to the increase of the critical depolarization.(5) There are two certain current intensities for producing two spikes with a constant current. The one limits the longest interval between them and the other limits the shortest one. Delayed rectification is mainly concerned with the existence of the former and the increase of critical depolarization contributes to the latter.
48 citations
TL;DR: The local system is to be considered as an autonomic apparatus which rules the beat of the heart, whereas the dorsal nerves convey the inhibitory and accelerator impulses from the central nervous system.
Abstract: 1. The three systems of nerves, viz. the local system, the regulator nerves, and the nerves of the arterial valves, which were previously described by the writer as innervating the heart of the Decapod Crustacea, have also been found in Squilla mantis. 2. The local system consists of not less than fourteen neurons. Their cells are situated in a nerve-trunk running alongside the dorsal surface of the heart, and, with the exception of the three anterior elements, lie at regular intervals each behind a pair of the ostial orifices. The cells give off the following processes: ( a ) the axons which form the chief part of the fibres in the ganglionic trunk and which after sending off many branches end on the muscle-fibres of the myocardium; ( b ) the dendrites--short arborescent branches arising both from cell-bodies and axons, and ending in the neighbourhood of the trunk on themuscle-fibres too; ( c ) short collaterals ending in fine networks of fibrils in the ganglionic trunk. 3. The system of regulator nerves connecting the local system with the central nervous system, in the Decapoda consisting of one pair of nerves, is represented in the Stomatopoda by three paired nerves which in our description have been termed Nervi cardiaci dorsales. For the designation of each of them the letters α,β, and γ have been used. Their course indicates that they originate in the large thoracic ganglionic mass. After passing on the dorsal side of the extensor muscles these nerves approach the heart from its dorsal side, and enter its ganglionic trunk in the region of the fourth body-segment. The nerve a is made up of one thick fibre only, the nerves β and γ contain one thick and several thinner fibres each. In the ganglionic trunk two sets of fibres given off by the dorsal nerves can be distinguished: one of them, termed System I, is made up of thicker fibres whose branches give synapses with the cells, collaterals, and dendrites of the local neurons; the other, called System II, consists of thinner fibres accompanying the long branches of the axons which pass to the muscles. 4. The system of nerves supplying the arterial valves is made up of ( a ) the anterior cardiac nerve running to the valve of the anterior aorta; and ( b ) the segmental nerves of the heart passing in each metamere to the valves of the paired arteries. There are, in all, fifteen pairs of these nerves. The last pair supplies the valves of the fifteenth pair of arteries and the valve of the posterior aorta. Each segmental nerve sends off anastomotic branches to the contralateral nerve, but does not show any connexions with the nerves of the neighbouring segments. In this respect these nerves in Squilla differ from those in the Decapods since in the latter they are all interconnected by anastomosing fibres. On the other hand, in Squilla as well as in Decapods the anterior cardiac nerve has no connexion with the segmental nerves of the heart. 5. With regard to the function of the nerve-elements enumerated above, the local system is to be considered as an autonomic apparatus which rules the beat of the heart, whereas the dorsal nerves convey the inhibitory and accelerator impulses from the central nervous system. The first of the dorsal nerves, α, has been found carrying the inhibitory impulses. The stimulation of the two following nerves, β and γ, quickens the beat of the heart, but this effect of the physiological experiment does not exclude the possibility that the nerves β and γ contain both inhibitory and accelerator fibres. The two sets of fibres in the ganglionic trunk which have been termed Systems I and II are probably concerned the former with the inhibitory and the latter with the accelerator action. The function of the nerves of the arterial valves probably consists in the maintaining of a tonic contraction of the muscles of the valves.
41 citations
"Electrical properties of the pacema..." refers background or methods in this paper
...Alexandrowicz (1934) also describes numerous dendrites and collaterals....
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...Following Alexandrowicz (1934), notations Os 1, Os 2, etc., will be used for them, numbering from the rostral end of the heart....
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TL;DR: The large supramedullary neurons (SMC) of an Atlantic puffer, Spheroides maculatus, exhibit some of these complexities, both the active as well as the passive, which form the subject of this paper, Part II of the present series.
Abstract: Intimate study of the electrical activity of various types of excitable cells, which has become possible with the use of intracellular recording, has disclosed numerous degrees of complexity in the phenomena by which bioelectric activity is produced. Excluding the different varieties of electrically inexcitable electrogenesis (28), and limiting consideration only to the electrically excitable form, several previously unsuspected phenomena have been observed. Different portions of the cell membrane have different excitabilities (3, 6, 7, 13, 17, 20, 24). Indeed, some parts of the cell may not respond to stimuli with spikes (2, 9, 22, 23, 40, 54). In the giant neurons of Aplysia or Helix small responses, \"pseudo pointes\" (53), may be recorded. In some varieties of cells, graded responses are produced either in the normal activity (11, 12, 30) or as a result of experimental conditions (1, 26, 27). As is shown in the present series of papers (4, 5), the large supramedullary neurons (SMC) of an Atlantic puffer, Spheroides maculatus, exhibit some of these complexities. The SMC offer a number of advantages for an attack upon several of these matters not only because of their size and superficial location. The cell body has only one large extension, a neurite which branches to form a number of unmyelinated axons (4). Thus, complications in the electrical circuit properties introduced by a myelinated segment, or by numerous dendritic arborizations (cf. references 16, 19, 22, 46) should be absent. These properties, both the active as well as the passive, form the subject of this paper, Part II of the present series.
40 citations
31 citations
"Electrical properties of the pacema..." refers background in this paper
...It is supposed that the apposed parts form an ephaptic junction between neurons and allow the conduction of spikes in either direction (Kao and Grundfest, 1957; Watanabe and Grundfest, 1961; Bennett, Aljure, Nakajima, and Pappas, 1963)....
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