CHAPTER XXX \' II 



Central autonomic mechanisms' 



W. R. INGRAM i State University of Iowa, Iowa City, Iowa 



CHAPTER CONTENTS 



Introduction 



Spinal Autonomic Mechanisms 

 Anatomical Considerations 

 Spinal Autonomic Reflexes 

 Interrelations With Higher Le\els 

 Spinal Shock 



Influence of Distance Receptors 

 Autonomic Mechanisms of Subdiencephalic Brain Stem 

 Reticular Formation 

 Medulla Oblongata and Pons 



Circulatory regulation 



Control of respiration and allied functions 



Other reflexes 

 Midbrain 



Central gray 



Control of urinary bladder 



Autonomic functions of oculomotor nerve 

 Diencephalic Autonomic Mechanisms 

 Anatomy of Hypothalamus 



Subdi\*isions of hypothalamus and their nuclei 



Afferent connections 



Efferent connections 

 Functional Considerations of Hypothalamus 



Body temperature control 



Hypothalamicohypophysial relationships 

 Hypothalamus and Behavior 



Sexual behavior 



Appetite and obesity 



Patterns of emotional behavior 



Sleep-waking mechanisms 



Other diencephalic relationships 

 Cerebral and Cerebellar Autonomic Mechanisms 

 Conclusion 



INTRODUCTION 



THE jACKSONiAN CONCEPT OF LEVELS of Central nervous 

 functions has been a very useful one because it has the 



' The results of some recent experiments by the author and 

 his colleagues are briefly touched upon in this paper. This work 

 was supported by USPHS grant M 375 {C3). 



appearance of simplicity, which is illusory, and fur- 

 nishes a logical basis for exposition. The central or- 

 ganization of autonomic function is but little different 

 from the somatic in this regard. Thus segmental pat- 

 terns exist in the spinal cord and also, so far as cranial 

 nerves are concerned, extend into the brain stem. 

 Reflex arcs for autonomic activity are developed at all 

 these segmental levels, and a certain ainount of local 

 integration of function is po.ssible. However, for the 

 greatest benefit of the organism as a whole these seg- 

 mental activities must be amalgamated, adjusted and 

 regulated so that the body is maintained in the best 

 possible condition to respond to the necessities imposed 

 by the often changing environment. Thus, supraseg- 

 mental mechanisms have developed in the brain stem, 

 the hypothalamus, the cerebellum possibly and the 

 cerebral hemisphere. Here again we see some evidence 

 of levels, for the medullary 'centers' are concerned 

 with relatively fundainental things, such as the regula- 

 tion of cardiac activity, vasomotor control and res- 

 piration. In the hypothalamus we al.so have forms of 

 organization which influence these basic functions, 

 but also much more coinplicated circuits are set up 

 which may be concerned with certain types of be- 

 havior, with the consumption of food and with the 

 various types of general responses to enxironmental 

 changes which bear sharply upon the individual. The 

 cerebral mechanisms for autonomic function have de- 

 veloped along with its somatic functions to a consider- 

 able extent, as Sherrington pointed out, along with 

 increased use of distance receptor mechanisms and 

 with the need for developing total patterns of behavior 

 which are the best suited for the needs of the bio- 

 logical type in question. The neopallial and archi- 

 pallial portions of the hemisphere interact with the 

 Inpothalamus and even lower regions in the brain 

 stem, not only to affect autonomic functions but also 

 to bring these functions into the behavioral structure. 



95' 



