The influence of natural sleep on focal spiking in experimental temporal lobe epilepsy in the monkey.

In 12 rhesus monkeys, made epileptic by injection of alumina cream into the temporal lobe structures, the changes of spike frequency were studied in wakefulness and natural sleep on 78 occasions. Five monkeys had a focus in the lateral surface of the temporal lobe and seven had a focus in the mediotemporal structures. Basic cortical and subcortical EEG patterns, recorded through chronic indwelling electrodes, showed fairly consistent changes in the course of natural sleep, allowing a classification of the sleep into stages. During slow wave sleep, the focal spikes increased in all 12 cases. The increase was more prominent during the light stage of slow wave sleep in the neocortical foci and during deep stage in the mediotemporal foci. During REM sleep, the mediotemporal foci showed a marked decrease of spiking, whereas changes in the neocortical foci were inconsistent.