1026 



HANDBOOK OF PinslOLOCiV 



NEUROPHYSIOLOGY II 



FIG. 7. Diagram of a mid-line 

 sagittal section through the hypo- 

 thalamus and pituitary gland. 

 Various hypothalamic nuclei 

 (D.M.N, dorsomedial nucleus; 

 M.N., mammillary nuclei; P..N., 

 posterior nucleus; PV.N., para- 

 ventricular nucleus; SO.N., 

 supraoptic nucleus; VM..N., ven- 

 tromedial nucleus) are indicated 

 in black. The stippled areas indicate 

 the sites where electrical stimula- 

 tion or lesions have resulted in 

 changes of pituitary secretion. 

 [From Harris (157)-] 



OXYTOCIC H. (?) 



ANTIDIURETIC H. 



CONAOOTROPHIC H. 

 6C.T.H. 



hack" mechanism. The hypothalamic site efiective in 

 producing an increased thyroid activity on stimula- 

 tion is in the region of the supraopticohypophysial 

 tract. This agrees well with tlie region in which lesions 

 are followed by a diminution in thyroid activity. 

 These results seem to bear a relation to factors which 

 seem of importance in the etiology of Graves' disease 

 [see discussions by Levin & Daughaday (209) and 

 Harris & Woods (165)]. The fact that too prolonged 

 stimulation of the hypothalamus in adrenalectomized 

 rabbits, in which thyroid activation occurs, may re- 

 sult in death of the animal is possibly related to the 

 fact that cortisone administration forms an effective 

 therapy in humans with thyrotoxic crises. 



HYPOTH.•\L.^MIC LOC.iiLIZ.ATION OF PITUl'IARY FUNC- 

 TION. It is likely that the control of the secretion of the 

 different pituitary hormones is represented by neural 

 mechanisms localized in different regions of the hypo- 

 thalamus, and that the areas concerned with different 

 hormones could be plotted on a map in a similar way 

 to the representation of the regions of the body in the 

 motor and sensory areas of the cerebral cortex. In the 

 latter case, however, the position is much simplified 

 in that a two-dimensional surface is involved and that 

 the afferent and efferent fibers all approach this sur- 

 face from one direction. In the case of the three- 

 dimensional hypothalamus, it would seem unlikely, if 

 the above conjecture is in any way true, that future 

 work will result in a simple picture of hypothalamic 

 localization since a multitude of reflex fibers, both 

 excitatorv and inhiiiitory in nature, must pass through 



the hypothalamus with an e\entual convergence in 

 the region of the 'final common path' — the tuber 

 cinereum and pituitary stalk. Howe\er, from the 

 meager information available at present, the position 

 may be summarized as in figure 7. 



TARGET GLAND .'\CTIVITY AND EXTRAHYPOTH ALAMIC 



REGIONS OF CENTRAL NERVOUS SYSTEM. Emotional 

 Stress is a potent factor in disturbing the normal pat- 

 tern of endocrine activity. The classic work of Cannon 

 and his colleagues relating adrenal medullary activity 

 with emotional excitement, of X'erney and iiis co- 

 workers in relating similar mental states with dis- 

 charge of posterior pituitary antidiuretic hormone, 

 and of later workers who found increased secretion of 

 adrenocorticotrophic hormone and decreased release 

 of thyrotrophic and gonadotrophic hormones under 

 these conditions may all be quoted in support of the 

 above statement. The term emotional stress is clearly a 

 very general term and it is likely that certain types of 

 emotional upsets may be more specifically related to 

 certain endocrine disturbances than are others (for 

 example the fear of pregnancy in connection with the 

 sudden onset of amenorrhea in the human female). 

 However in the present context there can be little 

 doubt that parts of the central nerxous system, remote 

 from the hypothalamus, may markedly modif\- endo- 

 crine activity. The effect of conditioned stimuli in 

 eliciting or inhibiting hormonal release, such as the 

 well-known discharge of oxytocic hormone that may 

 follow preparation for milking or suckling, may also 

 be mentioned. It is felt that further information 



