TRIGGERING OF DISCHARGES FROM AN EPILEPTOGENIC FOCUS IN RAT BY STIMULATION OF CONTRALATERAL HEMISPHERE - ONTOGENETIC STUDY

  • 1 January 1978
    • journal article
    • research article
    • Vol. 27  (1) , 15-22
Abstract
Fifty-two male albino rats aged 7, 9, 12 and 18 days and adult, immobilized with d-tubocurarine, were studied. Discharges were triggered from a penicillin focus with electrical pulses of double the threshold intensity needed to evoke an interhemispheric response [IHR]. Developmental changes in the IHR and in spontaneous interictal discharges did not differ from the results described in earlier studies. Practically no discharges could be triggered in 7 day old animals (only a few at a very low stimulation frequency). In the other age groups, discharges were triggered at 2 optimal frequencies, of which the lower one rose during development, while the higher one was relatively stable. With higher frequency triggering, marked signs of fatigue of the focus [intermittent triggering, loss of the main negative wave] appeared, especially in young animals. The averaged shape of triggered discharges was similar in 9 and 12 day old rats. It consisted of a 1st IHR positivity which triggered the 1st positive wave of the focal discharge, followed by a high negative wave. In the 18 day old and adult group, both initial positive waves merged to form a single wave. The duration of the individual waves of the triggered discharge was not significantly shorter than the duration of the corresponding waves of spontaneous discharge.

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