A METHOD TO STUDY THE EFFECTS OF AN EPILEPTIC FOCUS ON NONEPILEPTIC NERVOUS-TISSUE

Locally applied epileptogenic drugs directly affect the local cells wh ich project their epileptic activity into the surrounding tissue. This paper describes an experimental set-up which allows differentiation o f direct effects of an epileptogenic drug from indirect ones, which ar e synaptically projected. The set-up consisted of an experimental cham ber which enabled the isolated superfusion of a part of a nervous syst em with a drug. Isolated superfusion was obtained by means of a divide r between two compartments of the experimental chamber and of an outle t for the bath solutions below the divider. Quality of isolation was t ested with unilateral application of the epileptogenic drug pentylenet etrazole (PTZ) and of the dye methylene blue. Distribution of extragan glionic and intraganglionic PTZ was measured by PTZ-selective microele ctrodes. It was found that the drug could not be detected at the non-d rug side. Correspondingly, unilateral dye application resulted in a sh arp border between the treated and untreated side. The experimental se t-up was used to study projected events evoked by sustained epileptic activity of defined parts of a nervous system. It was found that the n on-treated cells became progressively coupled to the epileptic neurons in the course of the experiments.