STUART, D. G. 
cool directly in the posterior hypothalamus as distinct from the 
anterior hypothalamus. The results we got were not as clear-cut 
by any means as results we got from the stimulation anteriorly. I 
believe one can sum the case up by saying that the term you used, 
"blind," is not adequately descriptive. One must think of sensitivity 
to thermal changes in two contexts: one in which the sensitivity is 
either specifically related to a sense organ or sensory receptor as 
Dr. Hensel described, and the other in which any physical event can 
alter neuro-function. Presumably, these nerve cells in the posterior 
hypothalamus are like any others. If youcoolthem off enough, their 
activity will be impaired. If you heat them up enough, it may be in- 
creased for a while, but eventually it will be impaired. Therefore, 
in the physiological range ofbodytemperature or brain temperatures 
of 35 C to 41 C, one would be willing to say, under most circum- 
stances, there is no thermosensitivity, but outside of this range, 
there may be critical thermosensitivity in the sense that gross im- 
pairment of function of these cells may take place. 
DR. MINARD: Thank you very much. 
DR. HEMINGWAY: I may add one thing to that. Many years ago 
as Dr. Stuart mentioned, I heated the anterior hypothalamus with 
surface electrodes, and alsotheposterior hypothalamus. Heating the 
anterior hj^othalamus would cause instantaneous cutaneous vaso- 
dilatation and shivering would stop, but there was no effect whatso- 
ever on temperature regulation when the posterior hypothalamus 
was heated. One interesting thing occurred, which I am not sure 
was significant: the animals went to sleep immediately upon heating 
the posterior hypothalamus, but there is no rectal temperature 
regulation. 
DR. HENSEL: We found the same result as did Dr. Freeman. 
As yet, we have seen only these reactions during cooling the an- 
terior hypothalamus, but I would agree completely with your state- 
ment that there is no tissue in the body which is completely blind to 
temperature, of course. It is a matter of qualitative activity and of 
the direction. Some are excited and some are inhibited. 
DR. MINARD: You might say compared to the anterior hypo- 
thalamus, it is relative. 
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