Centralis superior raphe, reticularis pontis nuclei, and sleep-wakefulnesscycle in cats

This study examines the influence of lesions in the centralis superior raph e nucleus (CeSR) and adjacent paramedial pontine tegmentum on the sleep/wak efulness cycle (SWC) in cats. Sixteen cats had electrodes implanted for ele ctro-oculogram (EOG), electromyogram (EMG), electroencephalogram (EEG) and ponto-geniculo-occipital (PGO) recordings. There were 10 experimental anima ls: seven animals received diathermocoagulation lesions destroying between 7 and 27% of the CeSR; the remaining three cats suffered bilateral lesions in the paramedial portion of the reticularis pontis oralis (RPO) and caudal is (RPC) nuclei. Six sham-operated animals were used as controls. Recording s were taken of all animals in continuous 23-h sessions once a week for 12 weeks. Results indicated that the threshold for SWC state changes (increase of wakefulness (W) and drowsiness (D), and decrease of slow wave sleep (SW S)) after CeSR lesion is approximately 11.3% following volumetric destructi on of the nucleus. The amount of CeSR damage (CeSR-D) only correlated signi ficantly with the amount of W (positive correlation) and SWS (negative corr elation) during the first week post-lesion. The changes ill W over the cour se of the study were different in the two experimental groups. In both grou ps, total W was increased with respect to the controls, however, these incr eases were observed earlier in the CeSR-D group. The return to near control values in SWC state over days 15-28 of the study does not represent a defi nitive recovery by the CeSR-D cats. All the SWC states returned to control values by the tenth week in the cats with paramedial reticular pontine dama ge.