Amygdaloid kindling during wakefulness and paradoxical sleep in the cat. 1. Inhibitory influence of paradoxical sleep on kindling development.

The development of amygdaloid kindling during wakefulness (W) and paradoxical sleep (PS) was compared in chronically implanted adult male cats. The animals were divided into 2 groups. One group was kindled during W (W-K) and the second during a burst of pontogeniculo-occipital (PGO) potentials during PS (PS-K). The threshold of amygdaloid afterdischarge (AD) was determined during W in the W-K group and during PS in the PS-K group. For the development of kindling, amygdala stimulation was applied daily. Results demonstrate that kindling development was markedly retarded in the PS-K group. From the first kindling trials, mean AD duration in the PS-K group was significantly shorter than in the W-K group and this difference was sustained until generalized convulsive seizures (GCSs) were reached by the W-K animals. Also, mean AD frequency in the PS-K group was significantly lower than in the W-K group. AD propagation to the contralateral amygdala and sensorimotor cortex was significantly retarded in the PS-K animals. Time spent in behavioral stages I and II of kindling was significantly longer in the PS-K animals than in W-K animals and the number of daily electrical stimuli required to reach the first GCS was significantly higher in group PS-K than in group W-K. It is concluded that PS exhibits an inhibitory influence over amygdaloid kindling development and this influence is mainly exerted during the early stages of epileptogenesis.