FREEMAN, W. J. 
DR. FREEMAN: There is undoubtedly a problem related to the 
effect of the drug. I often suspected that pentobarbital had abnormal 
potentiating effects on shivering. I have induced shivering in an ani- 
mal, for example, with a relatively high rectal temperature, and I 
have seen shivering continue even when the brain temperature has 
passed 42 C or 43 C.Itisan abnormal condition, but if one wishes 
to study these unit potentials, it is better to have an abnormal condi- 
tion in which shivering can be obtained than one in which it cannot. 
DR. STUART: Still, after the lesions in this region, if the ani- 
mal is given pentobarbital, it does not shiver at an abnormally hi^ 
temperature. It is very difficult to get it to shiver even if the animal 
is cool. 
DR. FREEMAN: That is a valuable finding. I agree that the use 
of anesthesia introduces difficulties, although I would not say that it 
is to be deplored. 
DR. STUART: In the work that you did with unit recording, did 
you find any units that began before shivering began? 
DR. FREEMAN: Yes, we discarded those as sensory. 
DR. STUART: What regions were they? 
DR. FREEMAN: They were further laterally in the vicinity of 
the medial lemniscus and spino-thalamic tract. I did not stucfy 
those to any greatlengthbecause of limitations of time, but certainly 
the way in which to approach unit activity of this kind is to study 
every unit one can find that is correlated with anything. Other types 
of units we found were those which were initiated or increased in 
their discharge with this painful stimulus as opposed to the decrease 
we saw with shivering units. Those also would be of considerable 
interest. 
DR. STUART: Often in neurophysiology we think in terms of 
recording channels rather than brain activity. When using an oscil- 
loscope we are two-channel thinkers, i.e., the unit and the EMG. 
When using an EEG machine we are eight-channel thinkers. This 
imposes a "centristic" approach to the nervous system. 
290 
