Carbachol microinjection into the caudal peribrachial area induces long-term enhancement of PGO wave activity but not REM sleep

This study presents new findings of carbachol-induced long-term ponto-genic ulo-occipital (PGO) enhancement lasting five days, but without REM sleep en hancement. A quantitative analysis of the number and types of bilateral PGO wave events during slow wave sleep with PGO activity (SP) and REM was perf ormed in each of four cats over a period of six days following a single uni lateral microinjection of carbachol nanospheres into the caudolateral perib rachial area. The results demonstrate increases in the summed total of all PGO wave events to continue for five days postcarbachol reaching a peak six fold increase on day three in SP and REM. The tendency of PGO waves to occu r in clusters of greater than three waves increased sevenfold on day three in SP and fourfold during REM. These findings indicate a dissociation of lo ngterm PGO enhancement from long-term REM enhancement, and suggest that eve n a sixfold increase in PGO activity alone is not, in itself, sufficient to produce the cholinergic orchestration of REM sleep enhancement.