STUART, D. G. 
chloralose medication. The posterior hypothalamic stimulation did, 
however, abolish bilateral EEG spindle bursts, whereas the spindling 
persisted to a lesser degree during the septal stimulation. Thirty- 
two hours after chloralose medication, stimulation of the posterior 
hypothalamic locus evoked an immediate "burst" of shivering fol- 
lowed by subsequent milder bursts after the cessation of the stim- 
ulus. This response was evoked with a stimulus intensity of 400 \xK/ 
pulse. However, a stimulus intensityof 800 ^t A/pulse was necessary 
to evoke less intense but more continuous shivering during septal 
stimulation 33 hours after beginning anesthesia. When this intensity 
of 800 A^ A/pulse was used in stimulating the contralateral posterior 
hypothalamus 10 hours earlier than this last septal stimulation, 
more intense and continuous shivering was maintained for the 
duration of the stimulus, as shown later in Figure 14. 
As shown later in Table VIII, shivering could be produced both 
by septal and posterior hypothalamic stimulation from 9 to 24 hours 
after induction of alpha chloralose anesthesia. Shivering could also 
be produced during stimulation of these structures in cats anes- 
thetized with pentobarbital sodium. This indicates that the response 
was not solely a characteristic of alpha chloralose anesthesia. 
Figure 4 illustrates the somatic responses evoked by stimulation 
of avarietyof hypothalamic loci in 6 cats. In 13 other cats not listed, 
stimulation of one or more of these intermediate loci evoked re- 
sponses similar to those presented. The schemata of stimulated loci 
are based on reconstruction of electrode tracts from the buffered 
thionine sections of the appropriate brains. Plane A is a frontal 
section 10 mm anterior to the interauricular line and Plane B, 
9 mm anterior to this line. Loci 1, 2, and 3, and 10, 11 and 12 are 
2.5 mm from the midline, loci 4, 5, and 6 and 13, 14 and 15 are 
1.5 mm from the midline while loci 7, 8, and 9 and 16, 17 and 18 
are 0.5 mm from the midline. Loci land 7 and 10 and 16 are 10 mm 
dorsal to the interauricular line and loci 4 and 13, 9 mm dorsal to 
this line. Each locus shown is 2 mm ventral to any other locus in 
the same vertical plane. As previously mentioned, loci were stim- 
ulated at 1 mm depth intervals. These loci stimulation responses 
are not shown or discussedfor the sakeof clarity and in recognition 
of the accuracy limitations involved in comparir^ the specific loci 
stimulated in any one brain to those of another brain. The plane of 
brain section varies from one experiment to another, as does the 
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