CEREBRAL CIRCULATION

Abstract

In studying the circulation of the brain by direct observation of the pial vessels, Wolff and one of us (H. S. F.),¹Cobb²and others have presented evidence that constriction of the cerebral arteries in the intact animal may be accomplished by stimulation of the ipsilateral cervical sympathetic nerve. Histologic studies by Chorobski and Penfield,³moreover, suggest that there are efferent nerve fibers, originating in the cervical sympathetic trunk, which supply the ipsilateral arteries of the pia mater and the brain. Finesinger and Putnam⁴added support to these results by experiments on partially isolated heads perfused mechanically with the animal's own blood. In these perfusion experiments, however, owing to the preservation of the spinal cord and its vascular supply, the possibility of hormonal vasoconstriction (by reflex excitation of the suprarenal glands, for example, through the intact cord) cannot be discounted. A hormone so released, in fact,