Epilepsy and behaviour of the Mongolian gerbil: an ethological study.

Ethological procedures were used to compare behaviour characterizing seizure-sensitive and seizure-resistant gerbils and to examine motor components of their major convulsions. Seizure-sensitive gerbils showed less social investigation when encountering an unfamiliar resident than their seizure-resistant counterparts. Sequence analysis showed the motor components of major seizures to segregate into three largely independent groups comprising elements associated with clonic-tonic spasms, with subsequent extensor immobility and with returning abnormal activity which preceded the resumption of normal behaviour. In grade 4 and 5 convulsions, the motor components of clonic-tonic spasms included the elements "rigid upright posture," "foreleg treading," "fall over," "mouth spasms." Straub tail and opisthotonus which were not seen in grade 3 seizures. The durations of clonic spasms and extensor immobility were longer in seizures of grades 4 and 5 than in those of grade 3. The abnormal motor activity following extensor immobility was complex and unrelated to seizure severity. It is suggested that observational studies in epilepsy may contribute to our understanding of the underlying pathophysiological processes.