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Journal ArticleDOI

Pacemaker potentials for the periodic burst discharge 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 839-862
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.

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Citations
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BookDOI
01 Jan 1987
TL;DR: This chapter describes the efforts of cosmologists (and nature?) to form galactic and stellar structures, comments on them from the viewpoint of the homeokinetic principles, and pursues some parallels in the origin of life.
Abstract: 1 This chapter shows application of a consistent set of clear physical principles to describe the beginnings of the universe by the (hot) Big Bang model. The ultimate beginning presents difficulties for the physicist, particularly when it comes to explaining why we find a very inhomogeneous cosmos, instead of a uniform, radiating gas. Stars, globular clusters, galaxies, and clusters of galaxies dot space, but we cannot at present explain their presence without invoking a "deus ex machina." We expect ultimately to rationalize the existence of these local inhomogeneities through gravitational contractions of regions of higher than average mass density that in tum arise out of fluctuations, but the case cannot yet be made completely. Meanwhile, the Big Bang (incomplete) model deals with cosmic evolution in the large, as a balance between gravitational attraction and cosmic expansion. Its relationships are described by two simple equations derived from Einstein's theory of general relativity via local conservations of mass-energy and of momentum. Unfortunately, this model does not by itself produce the observed inhomogeneities. Neither the assumption of thermodynamic fluctuations following a "smooth" beginning nor that ofa chaotic beginning can itself account for stars and galaxies. A mystery remains. -THE EDITOR This chapter describes the efforts of cosmologists (and nature?) to form galactic and stellar structures, comments on them from the viewpoint of the homeokinetic principles (Soodak and Iberall, 1978) discussed elsewhere in this volume, and pursues some parallels in the origin of life. It appears that there are no serious problems in understanding the origin of stars, given the previous formation of a galactic gas mass. A number of reasonable, even likely, paths lead to star formation. On the other hand, the origin of inhomogeneities required to initiate galaxy formation is not yet known. Appendix 1 remarks on some advances in observational and theoretical cosmology made since the original writing of this chapter HARRY SOODAK • Department of Physics, The City College of New York, New York, New York

616 citations

Journal ArticleDOI
08 Jul 2004-Neuron
TL;DR: It is proposed that respiratory rhythm generation in normoxia depends on a heterogeneous population of pacemaker neurons, while during hypoxia the respiratory rhythm is driven by only one type ofpacemaker.

344 citations


Cites background from "Pacemaker potentials for the period..."

  • ...This has enabled us to ad(Carpenter, 1967; Connor, 1969; Watanabe et al., 1967), dress yet another important issue in neuroscience: the pacemaker neurons were subsequently discovered also ability of neuronal networks to flexibly generate different in the majority of mammalian neuronal networks…...

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Journal ArticleDOI
28 Apr 1978-Science
TL;DR: Findings emphasize the role of cellular properties as compared to synaptic wiring in the production of cyclic motor patterns by ensembles of neurons in the lobster stomatogastric ganglion.
Abstract: Many of the motor neurons in the lobster (Panulirus interruptus) stomatogastric ganglion exhibit plateau potentials; that is, prolonged regenerative depolarizations resulting from active membrane properties, that drive the neurons to fire impulses during bursts. Plateaus are latent in isolated ganglia but are unmasked by central input. These findings emphasize the role of cellular properties as compared to synaptic wiring in the production of cyclic motor patterns by ensembles of neurons.

255 citations

Journal ArticleDOI
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

References
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Journal ArticleDOI
TL;DR: An account of experiments designed to investigate the cardiac action potential by applying suitable pulses of current at various stages in the cardiac cycle is contained.
Abstract: Microcapillaries with an external tip diameter of 0 5p. (Ling & Gerard, 1949) can be inserted into single fibres of the cardiac syncytium and may be used to record resting and action potentials. The technique has so far been applied to the frog ventricle (Woodbury, Hecht & Christopherson, 1951) and to 'false tendons' of the dog and kid heart (Draper & Weidmann, 1951). The conductive system of the kid contains typical Purkinje fibres which are larger in diameter (40-lOOup.) than ordinary heart muscle fibres and which are only slightly contractile. In this preparation it is possible to insert two microelectrodes into the same fibre and to leave them intracellular for many minutes. Polarizing current can be applied through one electrode and the change in membrane potential -resulting from current flow recorded through the other electrode. The present paper contains an account of experiments designed to investigate the cardiac action potential by applying suitable pulses of current at various stages in the cardiac cycle.

468 citations


"Pacemaker potentials for the period..." refers result in this paper

  • ...Thus current strength necessary for abolition of the plateau is unusually high compared with that necessary in other materials (Weidmann, 1951; Tasaki, 1956; Tasaki and Hagiwara, 1957)....

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Journal ArticleDOI
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


"Pacemaker potentials for the period..." refers methods in this paper

  • ...To avoid the insertion of a second electrode we sometimes used a bridge circuit (Araki and Otani, 1955) to pass current through the cell membrane....

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Journal ArticleDOI
TL;DR: It is proposed that the fibers showing the largest fall in membrane potential during diastole are the pacemaker fibers of the heart, and that the rest of the preparation is excited by conduction.
Abstract: 1. Action potentials from sinus venosus and auricle fibers of spontaneously beating frog hearts have been recorded with intracellular electrodes. 2. Sinus fibers show a slow depolarization, the pacemaker potential, during diastole. The amplitude of this potential varies in different parts of the sinus. In some fibers the membrane potential falls by 11 to 15 mv. during diastole and the transition to the upstroke of the action potential is comparatively gradual. In other regions the depolarization develops more slowly and the action potential takes off more abruptly from a higher membrane potential. It is proposed that the fibers showing the largest fall in membrane potential during diastole are the pacemaker fibers of the heart, and that the rest of the preparation is excited by conduction. In auricle fibers the membrane potential is constant during diastole. 3. The maximum diastolic membrane potential and the overshoot of the action potential vary inversely with the amplitude of the pacemaker potential. The highest values were measured in auricle fibers. 4. Stimulation of vagi suppresses the pacemaker potentials. While the heart is arrested the membrane potential of the sinus fibers rises to a level above the maximum diastolic value reached in previous beats. In 28 experiments vagal stimulation increased the membrane potential from an average maximal diastolic value of 55 mv. to a "resting" level of 65.4 mv. The biggest vagal polarization was 23 mv. 5. In contrast to the sinus fibers vagal inhibition does not change the diastolic membrane potential of frog auricle fibers. 6. Vagal stimulation greatly accelerates the repolarization of the action potential and reduces its amplitude. These changes were seen both in the sinus and in auricle fibers stimulated by direct shocks during vagal arrest. 7. The conduction velocity in the sinus venosus of the tortoise is reduced by vagal stimulation. Block of conduction often occurs. 8. In the frog sinus venosus sympathetic stimulation increases the rate of rise of the pacemaker potential, accelerating the beat. The threshold remains unchanged. The rate of rise of the upstroke and the amplitude of the overshoot are increased. 9. The analogies between the vagal inhibition of the heart and the nervous inhibition of other preparations are discussed.

328 citations


"Pacemaker potentials for the period..." refers background in this paper

  • ...Much valuable information is now available on the pacemaker activity of the myogenic vertebrate heart (Hutter and Trautwein, 1956)....

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