Activity of preoptic neurons during synchronization and desynchronization.

Extracellular unit activity from 29 neurons in the preoptic area was recorded together with the cortical EEG in encéphale isolé cats. A majority (55%) of neurons showed alterations in their firing rates during transient changes in the EEG. Among them, a majority (62.5%) showed an increased firing rate during synchronization and the remaining showed an increased firing rate during desynchronization of the EEG. Most neurons showed a Poisson distribution pattern of firing during both the synchronized and the desynchronized phases of the EEG. The changes in the neuronal discharge occurring together with the specific changes in the cortical EEG fits in well with the assigned role of the preoptic area in the sleep-waking cycle.