Intracellular potential during electrically induced seizures

Sawa, Masaichi; Maruyama, Naoshige; Kaji, Shizuo

doi:10.1016/0013-4694(63)90090-7

Cited by 98 publications

(10 citation statements)

References 17 publications

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“…The mutually reenforcing influence of the radial DC-gradient with basal negativity, suddenly restored to an effective value, and the firing of pyramidal cells with propagation of the excitation to neighbouring cells through recurrent collaterals would then maintain the discharge during the clonic burst. This explanation is in agreement with observations by Li (29), Kandel et al (24, 25), Sawa et al (45) and Matsumoto and Ajmone Marsan (33), who in intracellular recordings showed that sudden depolarizations of the soma were associated with clonic bursts of seizure activity. DC-changes analogous to the negative resettings described here also occur during the clonic phase of neocortical seizures (9).…”

Section: A Proposed Negative Feedback Mechanism Involved In the Maintsupporting

confidence: 91%

A Consideration of Feedback Mechanisms in the Genesis and Maintenance of Hippocampal Seizure Activity

1964

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SUMMARY Hippocampal seizure discharge was investigated in lightly anaesthetized cats using extracellular microelectrodes. The interrelationships of rapid transients, unit discharge and slow DC‐shifts were studied. The genesis of hippocampal seizure discharge seems to depend upon the development of a positive feedback mechanism consisting of the mutually reenforcing action of increased firing of the pyramidal cells and the development of a radial DC‐gradient with negativity in the basal layers. Such a system has no inherent stability and one would expect it to lead rapidly to massive cathodal inactivation and arrest of seizure activity. This outcome is, however, not the rule, because seizure activity becomes stabilized by the development of a negative feedback mechanism involving probably the recruitment of inhibitory neurons and perhaps also partial cathodal inactivation of nerve cells. The seizure discharge may become arrested by one of the following three mechanisms: Failure of synaptic transmission within mutually interconnected neurons of the epileptogenic pool; Decay of the radial DC‐gradient (under natural conditions always resulting from factor (1)); Massive cathodal inactivation of nerve cells leading to spreading depression. RÉSUMÉ Les décharges critiques de l'hippocampe sont enregistrées chez le chat légèrement anesthésié, à l'aide de micro‐électrodes extra‐cellulaires. L'étude porte sur les interrelations entre les décharges unitaires et les variations lentes de potentiel. Les décharges critiques de l'hippocampe semblent dépendre du développement d'un mécanisme de “feedback” positif constitué par l'action mutuellement renforcée de la décharge progressivement croissante des cellules pyramidales et du développement d'un gradient “radial” de potentiel continu avec négativité dans les couches basales. Un tel système ne possédant aucune stabilité inhérente, on pourrait s'attendre a ce qu'il aboutisse rapidement à une inactivation cathodique massive et à un arrêt de la décharge critique. Une telle évolution n'est cependant pas la règle car l'activité critique se stabilise sous l'effet du développement d'un mécanisme de “feedback” négatif intéressant probablement le recrutement de neurones inhibiteurs et peut‐être aussi une inactivation cathodique partielle de cellules nerveuses. La décharge critique peut s'interrompre sous l'effet d'un des trois mécanismes suivants: Défaut de transmission synaptique dans les neurones mutuellement interconnectés d'un “pool”épileptogène; Diminution du gradient “radial” de potentiel continu (sous l'effet de conditions naturelles résultant toujours du mécanisme (no. 1)); Inactivation cathodique massive des cellules nerveuses aboutissant à une “spreading‐depression”.

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Section: A Proposed Negative Feedback Mechanism Involved In the Maintsupporting

confidence: 91%

A Consideration of Feedback Mechanisms in the Genesis and Maintenance of Hippocampal Seizure Activity

1964

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“…Numerous studies have been made in the past years with intracellular recordings from neurons in the mammalian central nervous system. Among those of the current period may be cited references (3,40,76,111,129,134,150,158,159,161,172,203). These data substantiate the view that neurons of the central nervous system in vertebrates have essentially the same basic properties as do neurons of the spinal cord (53) or various periph eral junctional systems (85).…”

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confidence: 70%

Effects of Drugs on the Central Nervous System

Grundfest¹

1964

Annu. Rev. Pharmacol.

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The editors instructed me to be "fiercely selective" in the material that I was to include in this chapter. In one respect that is an easily followed in struction for a general physiologist who studies cell membranes and attempts to use pharmacology as a tool to help decipher the electrogenic phenomena of excitable cells. Electrophysiology is fortunate in having a theory which links electrogenesis with the permeability of the cell membrane to ions (25, 100). The dazzlingly quantitative application of this theory to account for the spike of the squid axon (101) is meeting with the stubborn complexities of living membranes (13,14,95,144,188,189). Nevertheless, some rela tively simple modifications of the ionic theory permit the latter to account, although only qualitatively at present, for the bulk of a large variety of electrophysiological and pharmacological phenomena (84,85,89,90).The situation appears to be quite different in pharmacology. The periodi cal literature seems to be styled after the biblical "begat" chapters and much of it is about equally innocent of theory. Even in the restricted field of neuro pharmacology the data are almost entirely based on various reactions of whole animals or of their individual organ systems. When theory is attempted it seems to regard as irrelevant the morphology and functional properties of individual neurons and effectors, and of their organization into the complex organ system of the neuraxis and its peripheral appendages.In another respect, however, this instruction must be disobeyed. The present reviewer arrived at his interest in neuropharmacology from an at tempt to use a relatively simple conceptual framework, gained from the study of peripheral junctions (78 to 80), to account for the actions of drugs on cells, including those of the central nervous system (77, 81). The studies on electrocortical phenomenon with Purpura and other colleagues (82, 148, 151, 152, 154 to 156) in which pharmacological tools were used extensively 1 The survey of the literature pertaining to this teview was concluded in July 1963.

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“…13 found that when Cl ion in the incubation medium was replaced with large anions the seizure discharges were generated spontaneously as well as in response to electric stimulation.The general properties of the seizure discharge so induced were studied and are described below.A part of the findings has been published elsewhere in a preliminary account16).…”

mentioning

confidence: 99%