The occurrence of synchronous, self-sustaining seizure activity is one of the basic mechanisms underlying epileptic attacks. Using a mathematical model of neuronal network in various simulation experiments carried out in digital computer the conditions were studied of the development of pathological epileptic activity and the conditions of the parameters of this network affecting its stable function. After exceeding of a threshold value in the relation between the weights of the stimulating and inhibiting synapses an unstable epileptic response appears. In the state of the so called conditional stability the network is highly sensitive to even small changes of the parameters. These observations make possible a new look at a number of phenomena found in clinical cases and in experiments.

Action Potentials↗

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[Changes in synaptic potentials and axonal delays as factors causing epileptic instability of neuronal networks].

Synaptic weights, axonal delays and excitability thresholds are three basic parameters influencing the function of neuronal network as a dynamic system. Changes of the general level of the signal flow, without changes in relation between excitatory and inhibitory connections can cause pathologic oscillations in the network. The conductivity in neuronal nets depends on electrochemical processes and may be influenced by the pH-status, ion concentrations, among other parameters. Also different pathological processes can change it. Even slight changes of axonal delays, as shown above, can cause in certain situations unstable, epileptic oscillations of the net.

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Kindled seizures: anticonvulsant drugs and agents.

Repeated administration of an initially subconvulsive electrical stimulation results in a progressive intensification of the seizure activity, which is known as a kindling phenomenon. The stability of the kindling model of seizures is particularly useful for evaluation of the action of anticonvulsant drugs. In the present study the action of different substances on kindled seizures is reviewed. In general, there are two groups of substances; 1--classical antiepileptic drugs, which are widely used in treatment of human epilepsy and 2--a group of different kinds of biochemical and pharmacological agents, which have been shown to have an anticonvulsant action. In relation to the first group we present here only a brief review. As to the other group, physiological and pharmacological data are reported in order to explain the mechanisms of the anticonvulsant action.

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