STUART, D. G. 
so designed that their tops protruded by 1 mm from the calvarium. 
The electrodes were permanently fixed by a cement (NuWeld, L. D. 
Caulk Co.) to the calvarium, the lead-off electrode wires being 
soldered to a female plug (Winchester Electronics, Inc., Monobloc 
M 95), cement- attached to the skull also. Various muscles of the 
fore and hindlimbs were also implanted with electrodes using the 
previously described wire wrapping technique. The lead-off wires 
from the muscles were also soldered to the female plug via sub- 
cutaneous route. With this technique it was possible to implant a 
total of 8 bipolar brain and/or muscle electrodes, 4 electrodes and 
a ground electrode to each 9 pin receptacle (Monobloc M9P) which 
could be inserted into each female plug attached to the preparation's 
skull. The cables were so suspended that the animal could move 
freely within the confines of the Faraday cage. Electrical stimuli 
could be applied through any given electrode and recordings made 
from the other electrodes, all with apparatus previously described 
for acute stimulation studies. 
After consistent patterns of responses were obtained to stimu- 
lation via the various electrodes the animals were sacrificed, their 
brains fixed in formalin, sectioned every 80 /j , and alternate sections 
stained with buffered thionine to permit localization of electrode 
tracts. 
In Figures 16 and 17 the positions of the various electrodes in 
two such cats are shown schematically. In such sketches each 
electrode is numbered and drawn to brain scale. At the bottom of 
each sketch of a frontal plane of the brain a second number appears 
that is a code for the particular stained section of nervous tissue 
on which the sketch is based. 
Results and Comments. The responses of cats No. IM 2 and 
IM 6 typify the results and Figures 16 and 17 show the loci activated 
by electrical stimulation. In Cat No. IM 2 (Figure 16), shivering 
was produced during stimulation via electrode No. L , which, as 
shown in the upper lefthand sketch, would activate a dorsal mid- 
septal region. It was not produced during stimulation of electrode 
R , which was in a dorsal midseptal region but somewhat more 
lateral than electrode L . In this cat, shivering was also produced 
during stimulation of the posterior hypothalamic locus around 
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