Modification of Seizure Activity

Repeated electrical stimulation of certain brain areas in the rat can decrease thresholds for epileptiform after-discharge (AD) in those areas (Racine 1972). Motor seizures, which cannot initially be evoked by electrical stimulation of subcortical nuclei in the rat, can also be developed by daily electrical stimulation via implanted electrodes (Goddard et al. 1969). Goddard et al., however, recorded electrographic activity in very few rats and consequently presented little correlative data relating to AD thresholds and changes in the characteristics of the AD activity. Delgado and Sevillano (1961) found that AD durations increased in the hlppocampus of the cat with repeated electrical stimulation. Goddard (unpublished data, cited in Morrell 1969) has recently found a similar increase in AD duration in the amygdala of the cat, and Straw and Mitchell (1966) found that stimulation of the cortex in acute preparations (cats) also increased AD durations. The present paper seeks to extend these findings and to examine the relationship between the epileptiform after-discharge activity and the development of motor seizures.