STUART, D. G. 
involves the dorsolateral posterior hypothalamus and will return 
in the early postoperative period after any hypothalamic lesion 
that spares this region, then many seemingly divergent results can 
be explained. 
COMPARISON OF SOMATIC EFFECTS EVOKED 
DURING SEPTAL AND POSTERIOR HYPOTHALAMIC 
STIMULATION 
Anesthetized Preparation Studies 
Methods . In 7 experiments on cats anesthetized with either alpha 
chloralose (40 to 60 mg/kg I. P.) or pentobarbital sodium (35 mg/kg 
I. P.)i the septum was systematically explored for sites which 
when stimulated evoked somatic responses. In each experiment the 
intensity of stimulation needed to evoke shivering by stimulation of 
a dorsomedial posterior hypothalamic site was noted. In some of 
these experiments comparisons were also made of alterations in 
heart rates and respiration rates during septal and posterior 
hypothalamic stimulation. In these experiments an attempt was 
made to maintain the rectal temperature of each cat between 37 C 
and 38 C by appropriate alterations of environmental temperature. 
The surgical, electronic, brain fixing, sectioning, staining, and 
electrode tract location techniques were similar to those described 
above. 
Results. In five experiments (Cats No. ST 5, ST 13, ST 14, STl5 
and ST 17) the septal region was systematically explored for loci 
which when stimulated produced either an increase in muscle tone 
or shivering. The strongest somatic response evoked by stimulation 
of any given septal locus was com pared with the shivering response 
to posterior hypothalamic stimulation in the same cat. Comparisons 
were made of the latency and intensity of the response and the 
stimulus intensity necessary to evoke it. Additionally, in some 
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