112 



PHYSIOLOGY OF INDUCED HYPOTHERMIA 



2ao 



21.9 



23.6 

 24.7 



26.1 





U«c. 



Fig. 23.— Burst activity recorded from one locus (black dot) in the hippocampus at the indi- 

 cated cerebral temperatures. Inset shows a plot of the average frequency of the individual waves 

 of the bursts as a function of temperature. 



ordinates the process of arousal. Since the limbic system has been suggested as the 

 neuroanatomical basis of emotions/^'^- "^ it is of some interest that the newly 

 aroused hamster has been described as "being greatly enraged."^' 



The process of arousal as a coordinated physiological event. In summary, 

 the following changes have been recorded in the hamster during arousal from hi- 

 bernation : an increase in heart rate with the heart beating at a maximum rate for 

 any given temperature ; an abolition of A-V dissociation ; an increase in the velocity 

 of the cardiac impulse ; a rise in blood pressure ; a cutaneous vasoconstriction ; a 

 differential vasoconstriction between the fore and hind parts of the body ; an acti- 

 vation of the somatic muscular system ; an increase in oxygen consumption, and a 

 glyco-genolysis. In other terrestrial hibernators in which some of the saine measure- 

 ments have been made, like conditions have been reported. All these phenomena, 

 in the opinion of the atithors, can be correlated in the hypothesis that the process of 

 arousal is essentially a mass discharge of those parts of the nervous system which 

 govern heat production and conservation, and which give rise to functional activity 

 of the sympathetico-adrenal and somatic motor systems. Johnson^-'^ indicated that 

 this activity was maximal, for further stimulation did not increase the speed of wak- 

 ing in the ground squirrel, and this is confinned l)y the refractoriness of the heart to 

 epinephrine in the waking hamster.^" 



In spite of the importance of the sympathetico-adrenal system, neither the adrenrd 



