STUART, D. G. 
minations on the same and several animals before, three days after, 
and 28 days after decortication. 
LOCALIZATION OF THE HYPOTHALAMIC REGION 
ESSENTIAL FOR THE PRODUCTION OF 
SHIVERING 
Electrical Stimulation Studies 
Methods. An attempt was made to produce shivering by elec- 
trical stimulation of the hypothalamus of anesthetized cats with 
histological confirmation of the loci of stimulation which produced 
or failed to produce shivering. 
The cats were anesthetized either with alpha chloralose (40-60 
mg/kg I. P.) or pentobarbital sodium (35mg/kgl. P.). Each prepar- 
ation's brain was stimulated with a stainless steel concent ic bipolar 
electrode insulated but for 0.5mm of eachtip. The outer cylinder of 
each electrodehadadiameterof 0.4 mm and a thickness of 0.15 mm. 
The insulated inner wire was 0.1 mm in diameter. The resistance 
of each electrode was 30 to 50 megohms in 0.9 per cent saline. The 
electrode could be connected either to an electroencephalographic 
machine (Grass Instrument Co., Model HID) or, by way of a current 
monitor oscilloscope (The Heath Co., Model OL-1) and stimulus 
isolation unit (Grass Instrument Co., Model SI V-4 A), to a stimulator 
producing square wave stimulating currents of which the frequency 
duration and voltage could be regulated (Grass Instrument Co., 
Stimulator Model S 4C). To detect shivering and other somatic 
responses, electromyograms of fore and hind limbs were recorded 
on the electroencephalographic machine. Muscle electrodes con- 
sisted of either stainless steel electrodes (diameter 0.7 mm) in- 
serted into muscles 10 mm apart, or at the same distance apart, 
insulated stainless steel wires (outer diameter 0.25 mm) were 
wrapped aroundaportionof amuscle anda 2 mm length of insulation 
was removed from each wire on the inner surface of the muscle. 
314 
