Spontaneous cerebellar nuclei PGO-like waves in natural paradoxical sleep and under reserpine

PGO-like spikes were described in chronically implanted cats at the cerebellar nuclei, dentatus, fastigii and interpositus, bipolarly and monopolarly recorded during natural paradoxical sleep. They showed close similarities with known PGO at occipital cortex and lateral geniculate nucleus: wave form, duration and amplitude were coincident. Moreover fast activity frequency increment in the last part of slow wave sleep also was observed at cerebellar loci. The peak-to-peak latency measurements demonstrated that the occipital cortex PGO lagged the nucleus dentatus PGO-like waves in 20-22 msec. The phasic cerebellar waves were not always related to eye movements. Acute experiments with a previous low dose of reserpine showed the PGO-like spikes when an exploring electrode penetrated a cerebellar nucleus. Chronically implanted cats, treated with reserpine, showed the phasic cerebellar waves during wakefulness and, after a few days, during the recovered paradoxical sleep. Based on electrophysiology and the reserpine experiments a common pontine generating mechanism for PGO and cerebellar PGO-like activity is proposed. It is also hypothesized that the cerebellum could participate in sleep physiology mainly related to phasic events without excluding a tonic function.