Epileptogenesis is associated with heightened arousal responses in fish

Intramuscular injection of sodium penicillin in roach ( Rutilus rutilus) caused delayed habituation of arousal responses to repeated presentation of the onset of illumination or of a ‘tap’ stimulus. Topical application of aluminium hydroxide to the telencephalon of roach had a similar effect but was shown, also, to induce electroencephalographic seizures, in which the EEG amplitude was elevated from 4–20 times its normal level. Both treatments caused intermittent, abnormal ‘weaving’ behaviour and sporadic, violent, uncoordinated motor activity. In goldfish, Carassius auratus, topical application of aluminium hydroxide also caused delayed habituation of quantitatively measured, cardiac arousal responses to a moving shadow stimulus, compared to controls. This delayed habituation was, however, largely a result of the elevated magnitude of these arousal responses. The results are discussed in relation to brain mechanisms normally operative during arousal which may be hyperactive in epilepsy.