Sleep and waking activity of pontine gigantocellular field neurons.

The sleep and waking discharge of pontine gigantocellular field’ units was studied in unrestrained cats. Three cell types were distinguished on the basis of discharge rate. Type 1 had no spontaneous activity during quiet waking and sleep, discharging only during movements. Type 2 had high rates of tonic activity during both quiet waking and sleep. Type 3 had low activity rates during quiet waking and slow-wave sleep, but discharged in bursts during both waking movements and rapid eye movement (REM) sleep. Units with augmented discharge restricted to REM sleep were not observed. All pontine gigantocellular field cells discharged rapidly during specific waking movements at rates exceeding mean REM sleep rates. Among type 2 and 3 cells, REM sleep and active waking discharge rates were correlated, with cells that discharged rapidly in REM sleep also showing high rates during active waking. Adaptation to head restraint reduced waking motor activity and the correlated pontine gigantocellular field discharge, yielding a reduced estimate of waking discharge rates. Our results are consistent with an hypothesis of pontine gigantocellular field unit involvement in the motor activation common to both waking and REM sleep, but are not consistent with an executive role for these neurons in the triggering of the REM sleep state.