Changes in intracranial pressure elicited by electrical stimulation of the brainstem reticular formation in spinal cats with vagotomy.

The momentary changes in intracranial pressure (ICP) were explored using electrical stimulation of the brainstem reticular formation and the nucleus fastigii of the cerebellum in cats under artificial ventilation after spinalization (C2) and vagotomy. Regions that yielded an increase in ICP in the arterial pressor area were: the central part of the pontine recticular formation, the dorsal medullary reticular formation, the central part of the medullary reticular formation, and the nucleus fastigii of the cerebellum; and one region in the arterial depressor area was the paramedial and ventral medial region of the medullary reticular formation. Since the arterial blood pressure and respiration was maintained constant during electrical stimulation by spinalization and vagotomy, the increase in ICP in the cranium, a semi-closed box, momentarily reflected an increase in cerebral blood volume due to cerebral vasodilatation. It is suggested that excitation of cell bodies or fibres within these regions may produce cerebral vasodilatation.