ANTERIOR HYPOTHALAMIC I^ESIONS 
DR. CLARK: They were unilateral at two levels. You see, I have 
a virtual hemisection anteriorly on one side, and caudally on the 
other side. The third ventricle is convenient. There are no com- 
missural fibers in it. 
DR. HENSEL: May I make a more general comment on the eval- 
uation of impairment of thermode regulation of the lesion, here? I 
think I had better explain it on the blackboard. Mostly, we are 
speaking of a loss of the ability of the regulation against cold. We 
choose the temperature for testing this rather at random. I think it 
would be quite useful to test the ability of regulation systematically 
and quantitatively over the whole temperature range, because if you 
consider the curve of the poikilothermic and homeothermic or- 
ganisms as you showed in Figure 1, then the loss of the ability to 
keep the temperature at a certain level might have two explanations: 
one explanation is just limitation in the quantitative output of your 
regulating center; and the other might be a disturbance of the cen- 
ter — the feedback mechanism itself. So, if you have just a 
quantitative disturbance, the curve might regulate in a smaller 
range of temperature, but in Figure 24, your mechanism in terms 
of cybernetics and feedback is perfectly all right. It might be as 
precise as this one. This is the case, for example, in the pre- 
mature infant, and there are many wrong conclusions because the 
infant can not keep its temperature at this point, but it can maintain 
a perfectly normal temperature in this smaller range. 
DR. CLARK: That goes back to Isenschm id. 
DR. HENSEL: Yes, and I think it would be useful if you would do 
this. 
DR. CLARK: I have done it with some cats, but I did not have a 
good enough controlled room to really do it. You would have to have 
a pretty accurate room in order to test your animals properly. 
DR. HEMINGWAY: About this dual theory which we have been 
hearing of since before my time: the problem, I think, is trying to 
interpret the data. I was listening to Dr. Clark, who gave a very 
stimulating discussion of this. I justwonder if we have to be careful 
about being too rigid in defining the location and the functions of 
these centers. That is what it amounts to. You have a center in one 
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