Psychosomatic Medicine 23:403-412 (1961)
© 1961 American Psychosomatic Society

Digital Rheoplethysmographic Study of the Orienting Reflex in Man

¹ Department of Medicine, Tulane University School of Medicine and the Charity Hospital of Louisiana in New Orleans

The digital vascular reactions to the orienting reflex were studied in response to over 2000 orienting stimuli in several hundred normal and ill persons. The vessels of the finger tip are extremely sensitive and responsive to astonishingly mild orienting stimuli. These vasoconstrictive responses are interrupted when the sympathetic pathways to the vessels are blocked with procaine.

The vascular responses were found in the finger and toe tips and in the superior portions of the pinnae, being most sensitive in the finger tips and least sensitive in the pinnae.

The vasoconstriction not only involved the arterioles and small arteries but also the venules and veins of the digits. Because of the widespread nature of the dermal vasoconstriction, involving all vessels, relatively large shifts of blood must be associated with the reactions. The magnitude and sites of these sudden shifts of blood as well as the influence of the shifts on the function of the cardiovascular system in health and disease remain unknown.

The digital RPG, with its ability to record the orienting reflex, lends itself to studies of many central nervous system functions, especially the functional interrelationships of the cardiovascular and nervous systems. Aspects of sleep, hypnosis, and drug actions are among many central nervous system functions that can be observed through the medium of the digital RPG and the sensitive digital vascular effector organs.

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