CEREBRAL FUNCTION IN THE RAT 117 



On the following days he became more and more deteriorated 

 and was finally killed as he could no longer be induced to eat. 



An attempt was made to establish a conditioned reflex to con- 

 tact with the foot. The animal was fastened in the container de- 

 signed by Watson and the foot was fastened to a pointer in con- 

 tact with a kymograph. The dorsal surface of the foot was then 

 stimulated first by rubbing with the uncharged electrodes, then 

 electrically. The first effect of electric stimulation is a quick 

 jerk of the foot followed by an increased tonic contraction of 

 the muscles for standing so that the animal, with repeated stimu- 

 lation, rises gradually until he stands on the tips of his toes and 

 maintains that position for as long as three minutes. 



In the apparatus the animal's reactions became more and 

 more violent until, after the fourteenth stimulation he began to 

 bite his thigh and had to be taken out. For five minutes there- 

 after, when his right hind foot was touched he reacted by turn- 

 ing his head to the foot and squeaking. Fifteen minutes later 

 no reaction to contact with the foot was given. 



Lesion (plate II, fig. 34). The brain of this animal was one 

 of those improperly sectioned so that an exact delimitation of 

 the destroyed area has not been possible. As nearly as can be 

 determined there is a total destruction or degeneration of all 

 the cortex lying above and laterad to the third and lateral ven- 

 tricles, a separation of the frontal pole from all underlying struc- 

 tures at the level of the cerebral peduncles, a great shrinkage of 

 both corpora striata, and a destruction of the medial portion of 

 the occipital lobes. 



This animal had probably the greatest destruction of cerebral 

 tissue of any reported in this study. His instinctive exploratory 

 reactions were so limited that training on the ordinary laboratory 

 problems was impossible. He nevertheless showed an ability to 

 form very simple habits quite rapidly. 



Experiment 35. Deep transverse and horizontal incisions 

 were made in the cortex of a large male rat, 115 days old. He 

 recovered rapidly from the operation and gave no evidence of 

 motor disturbances or of other abnormality of behavior. 



Training in the simple maze (fig. 1) was begun six days after 



