Synaptic Events Underlying Spontaneous and Evoked Paroxysmal Discharges in Hippocampal Neurons

  • D. Johnston
  • P. A. Rutecki
  • F. J. Lebeda
Part of the Advances in Experimental Medicine and Biology book series (AEMB, volume 203)

Abstract

The cellular mechanisms responsible for the paroxysmal depolarizing shift (PDS) in cortical neurons have been studied extensively for over 20 years (Kandel and Spencer, 1961; Matsumoto and Ajmone Marsan, 1964a,b; Prince, 1966, 1968; Dichter and Spencer, 1969a,b; Matsumoto et al., 1969; Ayala et al., 1970; Lebovitz et al., 1971; Ayala et al., 1973; Wong et al., 1974; Prince, 1978; Schwartzkroin and Prince, 1978; Wong and Prince, 1978, 1979; Schwartzkroin and Wyler, 1980; Johnston and Brown, 1981; Wong and Prince, 1981; Traub and Wong, 1982; Wong and Schwartzkroin, 1982; Traub and Wong, 1983; Johnston and Brown, 1984b,c; Rutecki et al., 1985). The PDS, which represents the intracellular event that occurs during the interictal discharge — the signature of epileptogenic cortex — is a sudden depolarization of the neuron that triggers a series of action potentials (Matsumoto and Ajmone Marsan, 1964a,b). The membrane events that produce the sudden depolarization are still somewhat controversial (Prince, 1978; Johnston and Brown, 1981, 1984b, 1986; Alger, 1984). In previous work, both voltage-dependent and synaptic-conductance changes have been proposed to explain the origin of the PDS (Matsumoto and Ajmone Marsan, 1964b; Prince, 1966, 1968; Dichter and Spencer, 1969a,b; Ayala et al., 1973; Wong et al., 1974; Wong and Prince, 1978, 1979; Johnston and Brown, 1981; Wong and Prince, 1981; Traub and Wong, 1982; Wong and Schwartzkroin, 1982; Traub and Wong, 1983). With the recent application of voltage-clamp techniques to cortical neurons (Johnston et al., 1980), it has been shown that a large synaptic conductance change occurs in neurons during the interictal discharge (Johnston and Brown, 1981). This finding, as well as certain other results (Johnston and Brown, 1981, 1984b, 1986), provides the strongest evidence to date that large excitatory postsynaptic potentials (EPSPs) are involved in the generation of epileptiform activity in the cortex.

Keywords

Penicillin Neurol Haas CsCl Picrotoxin 

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Copyright information

© Plenum Press, New York 1986

Authors and Affiliations

  • D. Johnston
    • 1
  • P. A. Rutecki
    • 1
  • F. J. Lebeda
    • 1
  1. 1.Neuroscience Program, Section of Neurophysiology , Dept. of NeurologyBaylor College of MedicineHoustonUSA

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