TEMPERATURE REGULATION "CENTERS" 
and there are anatomical connections from the cerebellum to the 
nucleus of the field of Forel. I cannot see how you can conclusively 
say that the units you recorded are related to the efferent aspect 
of shivering. 
DR. FREEMAN: One can relate them to the shivering process, 
since they occur in association with it. What you are thinking of is 
the initiation of shivering. I do not think that they do this, since 
they usually begin after shivering has started. They are associated 
with the build-up of shivering, if you will, or the maintenance of the 
shivering at a level of adequate intensity. This tremor may or may 
not be shivering. A tremor in response to cold can occur in a de- 
cerebrated animal. I would think that the whole mechanism of shiv- 
ering exists downstream and what this part does is to facilitate this 
mechanism in response to the combined central- peripheral limbs of 
the cold receptor system. This means that this discharge is not 
necessaiy for the initiation of it, but it may be essential for the 
maintenance of an adequate degree of intensity. 
DR. STUART: It would be interesting to ablate the cerebellum 
and allow any rostral connection to the cerebellum with this region 
to degenerate and then see if you can still record these units. 
DR. FREEMAN: Well, a rather small proportion of the discharge 
comes up there in any case. Also, as we have seen, lesions of that 
area do not abolish shivering. I suspect that the re may be other parts 
of the brain which can do just as well, which also receive afferents 
from the cerebellum. 
DR. STUART: The units that were shown in this work were re- 
corded when animals were shiveringunder pentobarbital anesthesia, 
whereas after the lesions were made, the animals were tested in a 
cold stress in the unanesthetized state. Since this work has been 
done, I have made similar lesions in six animals in this subthalamic 
region — animals that, pre-lesion, could shiver under pentobarbital. 
After lesions had been made, the unanesthetized animals could still 
shiver in response to a cold stress, but they did not shiver under 
pentobarbital anesthesia. That makes me wonder whether or not 
there is a problem related to the effect of the drug on the response. 
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