Nonconvulsive limbic status epilepticus was induced by means of pilocarpine (15 mg/kg) in 10 LiCl-pretreated rats with implanted electrodes. The animals were exposed to an open field three times - just before pilocarpine injection, at the time when pathological EEG activity was unmistakably present in hippocampi (40-50 min after the pilocarpine), and when EEG activity turned to normal (120 min after treatment), each time for 10 min. Behaviour of the rats was monitored and 12 behavioural patterns were evaluated. Exploration (walking, rearing, sniffing) interrupted by periods of immobility and grooming prevailed in the pretreatment test. During pathological EEG activity, changes in both the total frequency, the total duration of behavioural patterns and the sequence of patterns and their expression were found. Furthermore, pathological patterns (head bobbing, chewing, staring spells) typical of nonconvulsive seizures appeared. Upon the postseizure test, pathological patterns disappeared. However, locomotor-exploratory activity of animals significantly increased. The activity corresponded to that of the first test. This finding suggests that habituation potency of animals with prior limbic seizures was impaired. In conclusion, limbic seizures induced by a low dose of pilocarpine resulted in changes in the structure of spontaneous behaviour and disturbed the processes related to the most elementary form of learning and memory.

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