FREEMAN, W. J. 
DR. HENSEL: I think that even the results of the acute experi- 
ments have a certain significance. Plasticity is no argument against 
this, because you can get the acute disturbance in one area while 
in another one, you do not, and this means something, even if there 
is afterwards a plasticity in a certain recovery. 
DR. FREEMAN: It may explain the difference then between the 
acute experiments and the results of the chronic experiments. 
DR. HEMINGWAY: I would just like to point out the need for 
further work on the unit potentials which occur in the midbrain and 
are associated with shivering. We still do not know just what part 
they play in the shivering process. They are there; they come on with 
shivering and they disappear when shivering stops. They are not 
quite in phase. I would like to ask if you removed the cerebellum 
and then looked for them . 
DR. FREEMAN: No, I did not do that. 
DR. HEMINGWAY: Dr. Stuart suggested that these midbrain 
unit potentials mi^t have come in from the cerebellum which is a 
possibility, but experiments should be conducted in which the cere- 
bellum is removed. 
DR. FREEMAN: They were seldom encountered in that part of 
the brain; that is to say, they were not in the brachium conjunctivum. 
DR. HEMINGWAY: And remember, if you make a hem isect ion 
below where you are recording, they are still there, so they are 
coming down from above but they migjit go a round-about way, by 
way of the cerebellum. 
DR. FREEMAN: I think that is a safe conclusion. 
DR. HENSEL: I have another question. I was quite interested in 
your finding of the relationship of arousal of behavioral activity to 
the potentials of the hypothalamus. We recorded recently the local 
blood flow in the hypothalamus by means of very thin implanted 
heated thermocouples in an unanesthetized cat, and we found that 
there is also very close correlation between the activity or arousal 
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