The Effect of Slow Wave Sleep and Rem Sleep on Regional Cerebral Blood Flow in Cats*

Abstract Regional cerebral blood flow was measured by means of an autoradiographic technique in unanaesthetized, unrestrained cats during wakefulness, slow wave sleep (S‐SW), and rapid eye movement sleep (S‐REM). The electrocorticogram, electro‐oculogram, and electromyogram from the posterior neck muscles were continuously recorded. All operative procedures were completed at least four days prior to the experiment. Arterial blood samples were obtained immediately prior to the regional cerebral blood flow determination and analysed for PCO 2 , PO 2 , pH, and haematocrit. There were no significant differences in these parameters among the three groups. During S‐REM there was a significant increase in flow in all twenty‐five regions measured which varied from 62 per cent in the cerebellar white matter and sensory‐motor cortex to 173 per cent in the cochlear nuclei. During S‐SW a significant increase in flow occurred in only ten of the twenty‐five regions, and these changes were smaller in magnitude, varying from 26 per cent in the association cortex to 68 per cent in the superior olive. It is postulated that local changes in cerebral metabolism account for the regional cerebral blood flow changes demonstrated.