Sleep and kindling: II. Effects of generalized seizure induction

Abstract Extensive sleep disturbance has been reported in epileptics. For various reasons, including medication influences, it is difficult to determine the source of these deficits in humans. Experimental models of epilepsy provide a convenient alternative in this regard as many of these problems can be avoided. Also, similar sleep deficits have been reported in humans and animal models, including preliminary evidence with kindling. The present study further examined the developmental influences of kindling on sleep, using 12-h polygraphic recordings. Twelve adult cats, surgically prepared for amygdala kindling and the evaluation of state variables, were divided into three groups: (I) kindled, (II) subthreshold stimulation, and (III) control. In all stimulated animals (groups I and II), initial afterdischarge (AD) thresholds were established. Subsequently, the animals were either kindled daily (group I) or received daily amygdala stimulation at a level 50% below the afterdischarge threshold (group II). Control animals were placed in the chamber daily but were never stimulated. Twelve-hour polygraphic recordings were obtained before and throughout the experiment in all groups. Animals in groups I and II showed a suppression of slow-wave sleep and a facilitation of waking with initial AD threshold testing compared with their own baseline and with controls. Slow-wave sleep was further depressed and waking increased by the end of kindling. Additionally, a significant suppression of REM sleep was obtained during kindling. In contrast, initial sleep deficits were maintained but not extended by subthreshold stimulation. These findings suggest an early and progressive association between sleep disturbances and epileptogenicity in the development of kindled seizures.