Cerebral Circulation

For several years it has been our good fortune to discuss with Wilder Penfield and his colleagues our laboratory and clinical observations on cerebral circulation. This cooperation developed into a plan to perform a few combined experiments, using the cranial window, as applied in our laboratory, on monkeys whose cerebral sympathetic supply had been unilaterally or bilaterally removed by Penfield. These experiments were carried out in March, 1931. In one of these monkeys, Penfield exposed the medulla oblongata and stimulated the different cranial nerves. To our surprise, no dilatation of the pial artery occurred when the trigeminal root was stimulated close to the medulla, but dilatation was observed when the facial root was stimulated, and when the vagus was stimulated. This experiment was done because ever since the work of Forbes and Wolff,1which showed that pial arteries dilate if the vagus nerve in the neck is stimulated, we