Il8o HANDBOOK OF PinslOLOUY -- NEUROPHVSIOLOG\' II 



XII 10 20 30 40 50 I 10 20 30 



38° 



37.5° 



37^ 



36.5° 



36° 



35.5° 



35° 



34 5° 



1 I I I 



Room26-6° 



warn Coot s.-nooth 



Room 26'8°C 



!-"5° Room +r5° 



FIG. 8. Reactions of a normal dog (interrupted tine) and of 

 three spinal dogs [solid line) upon transfer from a warm room 

 (+26.6°C) to a cold room (+ i °C). Spinal dog .-1 had a com- 

 plete transection through the eighth cervical segment of 580 

 days standing; dog 6, one at the eighth cervical segment for 

 40 days; dog C, one at the fifth to sixth cervical segment for 120 

 days. On external cooling, body temperature falls in the spinal 

 dogs and muscles innervated by spinal segments cranial to 

 transection exhibit shivering- [From Sherrington (181).] 



This result has been interpreted as evidence for the 

 existence of two anatomically separate coordinating 

 'centers,' one in the anterior hypothalamus regulating 

 against body heating, the other in the posterior 

 hypothalamus regulating against body cooling {'dual- 

 istic localization'). From a functional point of view, 

 on the other hand, central nervous regulaiion of body 

 temperature always involves reciprocal inhibition and 

 facilitation of all the different thermoregulatory 

 effector mechanisms in a quantitatively graded man- 

 ner ('unitary function'). Experiments with chronic 

 lesions have not revealed one definite cell congrega- 



nc. g. Schematic drawings of four frontal sections (A-D, 

 order of section caudalward) through the cat anterior hypo- 

 thalamus, showing extent of chronic electrolytic lesions in a 

 cat. .\fter the lesion a hot box test produced an increase of 

 rectal temperature to 4i.4°C without appearance of panting. 

 .Mibreviations as in (ig. 2. [From Clark et al. (52).] 



tion ('nucleus') or one specific pathway within the 

 hypothalamus to be responsible for thermoregulatory 

 mechanisms (52, 73, 186). Nor has it been possible to 

 define such localization from the results of local 

 thermal or electrical stimulation. 



The main conclusions from these observations are 

 a) that a thermoregulatory mechanism, which inte- 

 grates information from surface thermoreceptors and 

 central thermodetectors and coordinates the re- 

 sponses of the effector systems, is located in the 

 anterior and posterior hypothalamus; and b) that no 

 other such structure of similar importance exists in 

 the central nervous system. The first of these two 

 conclusions is generally accepted but the second is 

 not. It has been suggested that the heat-loss coordi- 

 nating mechanism (including the panting mechanism 

 in the cat but not in the dog) is situated partly in 

 the mesencephalon (30, 123, 124, 126). 



Discrepant results have been obtained from experi- 

 ments on animals with chronic high spinal transections 

 (45, iig, 161). According to Thauer (192, 193, 195), 

 spinal rabi^its may regain a satisfactory temperature 

 regulation if they are well kept for a sufficiently long 

 time after the transection; according to other investi- 



