ROLE OF THE PROSENCEPHALON IN SHIVERING 
to suppress shivering was greater during septal than anterior 
hypothalamic stimulation. The anterior h5^othalamic locus stimu- 
lated was within the region found to be most effective in inhibiting 
shivering (Andersson, 19 57; Dworkin, 1930). The septal locus of 
stimulation was within the ventromedial region of the midseptum. 
Figure 25 is a schematic representation of the effects of alter- 
ations in stimulus frequency on the intensity of stimulation necessary 
to suppress shivering. The pulse duration was maintained at 3 msec 
and the septal and hypothalamic locus stimulated within the pre- 
2 a 
viously described regions. In the three cats (ST 32 , 33 , and 34) 
less intense stimuli were necessary to suppress shivering at stim- 
ulus frequencies of 25, 50, and 100 pulses/sec than at 10 and 200 
pulses/sec. In two of the three experiments, stimuli of 100 pulses/ 
sec were less effective than 50 and 25 pulses/sec frequencies. In 
Cat No. ST 33 both septal and anterior hypothalamic loci were 
stimulated with less intense stimuli needed to suppress shivering 
during anterior hypothalamic than during septal stimulation. 
During experiments on the inhibition of shivering the dorso- 
medial portion of the posterior hypothalamus was routinely stimu- 
lated to illustrate an augmented response. It was observed that 
ventrolateral posterior hypothalamic stimulation suppressed shiv- 
ering. Two experiments on Cat No. ST 36 and 37 were conducted to 
compare the relative stimulus intensities necessary to suppress 
shivering during anterior and posterior hypothalamic stimulation 
to the relative stimulus intensities necessary to suppress shivering 
during septal and anterior hypothalamic stimulation of Cats No. ST 
33 and ST 34. In Cat No. ST 34 stimulation of a ventromedial 
mid septal locus suppressed shivering at a stimulus intensity of 
400 ju A/pulse. Stimulation of a supraoptic locus suppressed it at a 
stimulus intensity of 200 /u A/pulse, but stimulation of a dorsomedial 
posterior hj^othalamic locus augmented shivering. In all cases loci 
were stimulated at 5- minute intervals and the frequency of stimu- 
lation of 25 pulses/sec with a 3-msec pulse duration. 
Figure 26 illustrates the experiment on Cat No. ST 37 that 
confirmed the results for the experiment on Cat No. ST 36. That is 
to say, stimulation of anterior and ventrolateral posterior hypothal- 
amic loci suppressed shivering with stimulus intensities of 200 and 
150 ^A/pulse respectively, while stimulation of the dorsomedial 
369 
