Behavioural characteristics of wild jumping or running episodes in the double mutant spontaneously epileptic rat

Abstract

Spontaneously epileptic rats (SER) are homozygous for two mutations, zitter ( zi) and tremor ( tm), and spontaneously exhibit both absence-like seizure and tonic convulsion. In addition, wild jumping or running episodes sometimes appear without any previous stimuli. We recorded the behaviour on a video camera and/or a vibration response apparatus to examine the behavioural characteristics. All wild jumping or running episodes appeared within 27 s after termination of tonic convulsion with a frequency of 2·1%, and the episode could be detected even in the dark by using the vibration response apparatus. A rapid increase of high motor activity around the episodes was recorded as a single peak with high amplitude by the vibration response apparatus. The wild jumping or running episode appeared in all 4 SER at 8-14 weeks of age with a variable frequency, 0-9 times in the light period and 0-6·7 times in the dark period 8 h each week. Thus, the wild jumping or running episode was found to occur not only during the light period but also during the dark period without any significant difference in frequency.