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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512 citations
369 citations
TL;DR: The results reported here were obtained with a method of direct stimulation of single spinal motoneurons of Japanese toads using the same microelectrode with certain compensation circuits for both stimulation and recording.
Abstract: THE ACTIVITIES of single nerve cells explored with intracellular electrodes have been reported by several authors (1, 3, 4, 14). In those reports researches whether were made in connection with orthodromic or antidromic. It the excitation via neural is desirable, however, to pathways, adopt the method of direct stimulation in order to get more detailed knowledge concerning the physiological properties of the soma membrane. Since the insertion out ordinarily without of microelectrodes into the visual control, there is no neurons must be carried possibility of having two separate microelectrodes lodging in the same neuron, the one for stimulation and the other for recording. The use of a twin-microelectrode was also found inappropriate for the present purpose, because of the electrical interference between each electrode due to their capacitative coupling. The only method available was therefore to use the same microelectrode with certain compensation circuits for both stimulation and recording. The results reported here were obtained with such a method on single spinal motoneurons of Japanese toads.
332 citations
"Electrical properties of the pacema..." refers background in this paper
...In the motoneurons of toads and cats, direct stimulation produced a spike in the initial segment before the soma-dendritic membrane was excited (Araki and Otani, 1955; Frank and Fuortes, 1956; Coombs, Curtis, and Eccles, 1957)....
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...This property is observed in many other nerve cells, for example, the toad or cat motoneurons (Araki and Otani, 1955; Coombs, Curtis, and Eccles, 1957), the stretch receptor cell of a lobster (Edwards and Ottoson, 1958), although there are some exceptional neurons, for example, the supramedullary cells of the puffer (Bennett, Crain, and Grundfest, 1959)....
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317 citations
TL;DR: Curves of the strength of the stimuli required for eliciting small or full spikes have been constructed in a number of conditions and it is assumed that threshold of the major portions of the soma membrane is higher than the threshold ofThe axon, the transition occurring over a finite area near the axon hillock.
Abstract: 1. Spikes evoked in spinal motoneurons by antidromic stimulation normally present an inflection in their rising phase. A similar inflection is present in spikes evoked by direct stimulation with short pulses. 2. In either case the inflection becomes less prominent if the motoneuron membrane is depolarized and more prominent when it is hyperpolarized. Both antidromic and direct spikes may fall from the level of the inflection thus evoking a "small spike" only if sufficient hyperpolarization is applied. Similar events occur when antidromic or direct spikes are evoked in the aftermath of a preceding spike. 3. Spikes evoked by direct stimuli applied shortly after firing of a "small spike" may also become partially blocked at a critical stimulus interval. At shorter intervals, however, spike size again increases and no inflection can be detected in the rising phase. 4. When a weak direct stimulus evokes a small spike only, a stronger stimulus may evoke a full spike. Curves of the strength of the stimuli required for eliciting small or full spikes have been constructed in a number of conditions. 5. To explain the results it is assumed that threshold of the major portions of the soma membrane is higher than the threshold of the axon, the transition occurring over a finite area near the axon hillock. Following antidromic or direct stimulation, soma excitation is then initiated in the region of the axon hillock. Spread of activity towards the soma occurs at first slowly and with low safety factor. At this stage block may be easily evoked. Safety factor for propagation increases rapidly as the growing impulse involves larger and larger areas of the soma membrane so that, once the critical areas are excited, activation of the remaining portions of the soma membrane will suddenly occur.
290 citations
"Electrical properties of the pacema..." refers methods in this paper
...In the present paper, the initial part of the action potential will be called A spike, and the later part B spike, in accordance with the notation adopted by Fuortes, Frank, and Becker (1957)....
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