The tuning of the nervous system: physiological foundations and implications for behavior

Abstract

THE TUNING OF THE NERVOUS SYSTEM: PHYSIOLOGICAL FOUNDATIONS AND IMPLICATIONS FOR BEHAVIOR E. GELLHORN* Since central excitation of autonomic structures leading to changes in behavior invariably alters tone and activity ofthe striated muscles, it was thought that the study ofautonomic reflexes in their action on autonomic "centers" in the brain stem (particularly the hypothalamus) and also on various levels ofthe somatic nervous system may lead to a better understanding of autonomic-somatic integrations and behavior. Experiments showed indeed that reflexes leading to increased sympathetic or parasympathetic discharges alter the reactivity ofboth autonomic divisions and alsothestate ofthesomatic system in a predictable manner [1-3]. Thecentralnervous system seemed to be "tuned" specifically by stimuli or conditions producing changes in hypothalamic excitability and balance. With the recognition ofthe intimate relations between limbic brain and hypothalamus by MacLean, Nauta, Papez, Tokizane, and others [4-7] and in view ofthe growing comprehension ofautonomic-somatic integrations [8], the time seems ripe to investigate the validity of the concept of tuning and its laws for neurophysiological problems on a broad basis and to apply it to the study ofbehavior. I. The Tuning ofthe Hypothalamus The procedure employed in these studies is simple. The effects of a stimulus A evoking an autonomic vascular reflex (through lowering of sino-aortic pressure) and ofa stimulus B applied to th…