CENTRAL CONTROL OF DIGESTIVE FUNCTION 



I 169 



made an extensive study of the mechanisms by which 

 liypotlialamic stimulation increased acidity and found 

 that this could occur not only via the vagal nerves 

 but also via the pituitary and the adrenal glands (32). 

 A remarkable fact is the considerable latency of the 

 change in acidity (i to 2 hours). According to the 

 authors the results were reliable and could be re- 

 peated. Shealy & Peele (83) found that stimulation of 

 the amygdaloid in unanesthetized animals causes a 

 definite increase in gastric acid content which com- 

 pared favorably with that after histamine alone. 

 They did not study the concomitant changes in mu- 

 cus and pepsin secretions. These authors assumed 

 that the effect of stimulating the amygdaloid nuclei 

 could be mediated via histamine or via parasympa- 

 thetic fibers in the vagus ner\e. The pathways in- 

 voked between the amygdaloid nuclei and the \agus 

 nuclei remain unknown; it is possible that the con- 

 nections between the amygdaloid nuclei and the 

 hypothalamus may lead to acti\'ation of the hypo- 

 thalamic area already earlier indicated. All types of 

 changes in gastric secretions were obtained by Anand 

 & Dua (4) on stimulation of temporal lobe structures 

 with indwelling electrodes in unanesthetized cats. 

 These authors consider the possibility that this effect 

 is transmitted through the hypothalamus. 



It seems unlikely that in the normal organism an 

 increase in gastric secretion would occur without 

 concomitant changes in gastric motilit\' and \aso- 

 motor tone. If the changes in gastric secretion are 

 mediated via a hormonal mechanism, the immediate 

 changes in gastric motilitv in response to emotions, 

 \estibular stiinuli or olfactory stimuli may not be 

 long lasting enough to elicit a change in gastric secre- 

 tion also. If this is the case, central control of gastric 

 secretions occurs only in processes associated with 

 digestion of food. 



EMOTION.'KL INFLUENCE ON DIGESTIVE FUNCTION 



Any emotional process can be said to consist of a 

 subjective experience, a type of neurophysiological 



reaction and a mode of behavior (20). The neuro- 

 physiological reaction may affect one or many .sys- 

 tems. The effect of emotions on the gastrointestinal 

 tract varies, and it has been difficult to correlate a 

 specific type of gastrointestinal change with any 

 particular emotional change. Superficial emotional 

 reactions may sometimes cover basic disturbances 

 which are responsible for digestive function dis- 

 turbances (62). 



Emotional stress affects all parts of the gastroin- 

 testinal tract (28). Salivary secretion can be increased 

 (69, 92) or decreased (95). Also, the composition of 

 the saliva changes (95). .Secretion of gastric juice is 

 easily influenced by anger, joy, anxiety states, etc. 

 (14, 96). The change in secretion is associated with 

 or preceded by changes in motility (18). Secretion of 

 intestinal juices and bile has been reported to fluc- 

 tuate under emotional stress (69, 76, 95). Anger and 

 hostility lead to hyperactivity of the colon; fear, to 

 immobilization (39). Many of the older reports deal 

 with the correlation between superficial emotions 

 and gastrointestinal changes and do not take into 

 consideration deeper emotional conflicts. If a change 

 takes place in the electrical acti\'ity of the brain as a 

 result of emotion, the change, if cortical or sub- 

 cortical, will be reflected in other parts of the brain 

 — mainly the reticular formation but also the areas 

 to \vhich the reticular formation projects (56). The 

 changes may be of excitatory or inhibitory nature 

 and can presumably also be excitatory in one part 

 and inhibitory in another part of the brain (55). 

 The net eff'ect will be hard to predict and the number 

 of possible combinations is unlimited. Under normal 

 conditions the emotional influence will not be of 

 major importance. One does not, however, have to 

 postulate abnormal pathways for the influence of 

 emotions on the digestive functions. Most of the struc- 

 tures that have been implicated in the neurophysio- 

 logical basis of emotions have adequate connections 

 with the lower brain-stem structures concerned with 

 digestive function. If and when we learn to translate 

 psychiatric terms into neurophysiological language, 

 it will be easier to interpret the effects of emotions on 

 gastrointestinal function. 



REFERENCES 



1. .AiDAR, O., W. A. Geohecan and L. H. Ungewitter. J. 

 .\europhysiol. 15: 131, 1952. 



2. Amassian, V. E. J. Neurophvstol. 14: 433, 1951. 



3. Amassian, V. E. J. Neurophysiol. 14; 445, 1951. 



4. .-Xnand, B. K. and .S. Dua. Indian J. M. Res. 44: IJ5, 

 ■956. 



5. Andersson, B., S. N. Landgren and Y. Zotterman. 

 Acta physiol. scandinav. 20; 253, 1950. 



