Respiratory effects of preoptic-anterior hypothalamic electrical stimulation during sleep in cats

The respiratory effects of preoptic-anterior hypothalamic (PO-AH) and vagal repetitive electrical stimulation (RES) were studied in unrestrained cats during sleep. PO-AH RES influenced breathing consistently during synchronized sleep but only occasionally during desynchronized sleep. Induction of desynchronized sleep by PO-AH RES was also observed. The respiratory effects of PO-AH RES on one side were enhanced by concomitant PO-AH warming on the other side during synchronized sleep but not during desynchronized sleep. Breathing was affected by vagal RES during both sleep stages, although an increase in threshold and in variability of respiratory responses was apparent during the latter sleep stage. The results show that PO-AH unresponsiveness during desynchronized sleep is nonspecific.