CEREBRAL CIRCULATION

Abstract

Central stimulation of the vagus nerve in animals is followed, under certain conditions, by dilation of arteries in the pia-arachnoid. When first reported in 1928 this dilation was thought to be a simple vasomotor reaction1which would involve nerve fibers passing upward from the medulla to the arteries in question. Such an interpretation was supported by the work of Cobb and Finesinger2and of Chorobski and Penfield.3 Despite these observations, the exact conditions determining the arterial dilation were not fully understood. In some experiments the caliber of the arteries seemed to be affected by changes in the blood pressure, the respiration or the strength of the stimulus; in others, no such relationship could be made out. Furthermore, it was difficult to reconcile our observations with those of other workers, notably Schmidt.4 During the past two years we have studied the problem again with the hope of