Abstract
Neuronal response to single stimuli was investigated in a cortical slab isolated from immobilized cats before, during, and after onset of induced epileptic states. Neurons of the isolated cortical slab were found to generate EPSP and paroxysmal depolarizing shifts (PDS) in membrane potential (MP) during the development of generalized epileptoid activity; these occurred together with refractory periods. Duration of the latter corresponds with the PDS plateau and repolarizing shifts in MP. Single electrical stimuli induced gradual alteration in PDS as these shifts developed. Neurons still maintain their ability to generate PDS arising in response to presentation of single stimuli once ictal activity has ceased. Postsynaptic response is not thought to play a decisive role in the genesis of epileptoid activity. Nonspecific factors and especially alterations in the concentration of electrogenic ions apparently contribute to this phenomenon.
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Literature cited
V. É. Lopantsev and V. D. Taranenko, "Neuronal electrical activity of an epileptic focus produced by electrical stimulation in an isolated cortical slab," Neirofiziologiya,20, No. 3, 357–365 (1988).
V. M. Okudzhava, S. M. Papitashvili, and I. A. Mzhaviya, "Inhibitory processes in epileptoid foci of the cat sensorimotor cortex," Fiziol. Zh.,31, No. 5, 589–592 (1985).
A. I. Roitvak and I. V. Ocherashvili, "Altered concentration of extracellular potassium in the cortex during electrical stimulation of different parameters," Fiziol. Zh., SSSR,73, No. 2, 277–283 (1987).
G. F. Ayala, M. Dichter, R. I. Gumnit, et al., "Genesis of epileptic interictal spikes: new knowledge of cortical feedback systems suggest a neurophysiological explanation of brief paroxysms," Brain Res.,52, No. 1, 1–17 (1973).
M. Y. Gutnick, B. W. Connors, and D. A. Prince, "Mechanisms of neocortical epileptogenesis in vitro," J. Neurophysiol.,48, No. 6, 1321–1335 (1982).
M. Y. Gutnick and D. A. Prince, "Effects of cortical epileptiform discharges on neuronal activities in cat VPL. 1. Interictal discharges," J. Neurophysiol.,37, No. 6, 1310–1327 (1974).
V. V. Hablitz, "Picrotoxin-induced epileptiform activity in hippocampus: role of endogenous versus synaptic factors," J. Neurophysiol.,51, No. 5, 1011–1027 (1984).
U. Heinemann and H. D. Lux, "Ceiling of rises in extracellular potassium activity in the cerebral cortex of cats," Brain Res.,120, No. 2, 231–249 (1977).
D. Johnston and T. Brown, "Giant synaptic potential hypothesis for epileptiform activity," Science,21, No. 4479, 294–297 (1981).
H. Matsumoto, G. F. Ayala, and R. I. Gumnit, "Neuronal behavior and triggering mechanism in cortical epileptic focus," J. Neurophysiol.,32, No. 5, 688–703 (1969).
I. L. Noebels and D. A. Prince, "Development of focal seizures in cerebral cortex: role of axon terminal bursting," J. Neurophysiol.,41, No. 5, 1267–1281 (1978).
D. A. Prince, "Neurophysiology of epilepsy," Annu. Rev. Neurosci.,1, No. 3, 395–415 (1978).
P. A. Schwartzkroin and D. A. Prince, "Cellular and field potential properties of epileptogenic hippocampal slices," Brain Res.,47, No. 1, 117–130 (1978).
G. W. Sypert and A. A. Ward, "Changes in extracellular potassium activity during neocortical propagated seizures," Exp. Neurol.,45, No. 1, 19–41 (1974).
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I. I. Mechnikov State University, Odessa. Translated from Neirofiziologiya, Vol. 21, No. 2, pp. 198–204, March–April, 1989.
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Lopantsev, V.É., Taranenko, V.D. Neuronal response in an epileptically excited isolated cortical slab to single electrical stimuli. Neurophysiology 21, 149–153 (1989). https://doi.org/10.1007/BF01056973
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DOI: https://doi.org/10.1007/BF01056973