EFFECT OF STIMULATION OF BRAIN-STEM RETICULAR FORMATION ON CEREBRAL BLOOD FLOW AND OXYGEN CONSUMPTION

The brain-stem reticular formation in the pons was stimulated in twelve monkeys while recording cerebral blood flow and oxygen consumption by the use of electromagnetic flowmeters and cerebral arterio-venous oxygen differences. During stimulation, cerebral blood flow and oxygen consumption usually increased if the EEG showed desynchronization. The EEG desynchronization was associated with a mean increase in cerebral oxygen consumption of 7.7% and an increase in cerebral blood flow of 9.7%. After discontinuing the stimulation, cerebral oxygen consumption returned to the steady state within 3 min while the EEG reverted to the resting pattern immediately after the stimulus was discontinued. Less well defined EEG changes were induced by stimulation of the femoral nerve, weak stimulation of the reticular formation or after transection of the cerebral spinal cord. Such poorly defined EEG changes were associated with little or no increase in cerebral blood flow and oxygen consumption. The increase of cerebral blood flow appeared to be caused by increased cerebral metabolism associated with EEG desynchronization. © 1969.