EXPERIMENTAL STUDIES ON THE THALAMUS 19 



Munk ('90) stated that the restlessness of the decerebrate 

 pigeon was dependent on hunger. 



Exner and Onimus repeated the studies on chickens and ducks, 

 and Kalischer more recently has tried cerebral ablations on the 

 parrot. 



Luciani has referred to the fact that the decerebrate rabbit 

 will make spontaneous movements if the thalamus is intact. 



Goltz's decerebrate dog showed continued restlessness, and in 

 the autopsy report of Holmes it is stated that the thalamus is 

 intact, but shrunken, due to secondary degenerations. 



Bechterew and his students have attempted to get some defi- 

 nite experimental evidence on thalamic functions. He finds 

 thalamic injury leading to lowered reflex excitability, forced 

 movements which he suggests are cerebellar in origin, statis 

 of food in the gastric organs,. and a characteristic flattening of 

 the feathers against the body instead of fluffed as in the sleeping 

 or decerebrate bird without thalamic lesion. Furthermore, he 

 considered that there were thalamic centers for the respiratory, 

 digestive, circulatory, and urogenital organs. 



Sachs recently tested these hypotheses by stimulation methods, 

 and concluded that reflex effects on these organs can be obtained 

 by thalamic stimulation, but that there are no controlling cen- 

 ters of these organs in the thalamus. 



METHODS 



Decerebration in the pigeon is a relatively simple matter. Ex- 

 perience, however, showed two factors particularly which should 

 be closely watched. First, when the cranial vault is removed, 

 care must be taken that the underlying dura mater be left intact. 

 If this is rudely torn, mechanically the pathways for the circu- 

 lation of blood through the brain stem are so interfered with as 

 to lead to inefficient blood supply. It seems that this effect is 

 due to damage to both the sinuses and the arteries on the lower 

 surfaces of the brain. This may lead either to excess intracran- 

 ial hemorrhage with resulting pressure complications or to defi- 

 cient blood supply. Sometimes, however, it is found that the 

 animals recover in spite of torn meninges. 



