Desynchronized sleep-like pattern of sympathetic activity elicited by electrical stimulation of sites in the...

In unanaesthetized mid-collicular decrebrate cats, paralyzed and artificially respired, recordings were made of sympathetic activity in nerves to heart (CN), to kidney (RN) and in identified vasoconstrictor nerves to skeletal muscle (SFM), whilst stimulating electrically with monopolar electrodes at various sites throughout the pons and medulla. Comparing RN and SFM, 1 of 3 patterns of response was observed at any one site: an increase in RN and SFM activity, a reduction or abolition of activity in both or a reduction or abolition of RN activity with a simultaneous facilitation of SFM activity. The latter differential pattern of sympathetic activity is characteristic of desynchronized sleep-like periods and could only be elicited from a discrete region in the mid-line of the caudal brainstem. Stimulation in this same region produced a reduction or abolition of CN as well as RN. It was suggested that neurones within the caudal part of nucleus raphe obscurus can generate a pattern of sympathetic activity similar to that occurring naturally in desynchronized sleep.