CEREBRAL FUNCTION IN THE RAT 



111 



and seemed fairly normal in behavior. She was placed in the 

 restraining cage and ran about actively for five minutes but did 

 not get up to plane. She seemed suspicious and explored with 

 neck extended. She then settled down at the back of the box 

 and remained motionless for an hour. On the two days follow- 

 ing this behavior was repeated. There was never any specific 

 reaction to the situation and after the first five minutes there 

 was no normal exploration; she did not get on top of the food 

 box in three hours on three consecutive days. She also was 

 abnormally wild and tried to escape when picked up. 



Lesion (plate III, fig. 33). Right hemisphere. There is a 

 lesion extending diagonally forward from above the hippocampus 

 along the course of the external capsule over the corpus striatum 

 to the base of the olfactory bulb, severing all the fibers laterad 

 to the forceps of the corpus callosum but leaving the mesial 

 surface of the pole intact. The lesion is filled by a large clot. 



Left hemisphere. The lesion extends somewhat farther back 

 than that on the right, passing down through the anterior third 

 of the corpus striatum into the lateral half of the cerebral pe- 

 duncle. The mesial surface of both hemispheres is probably 

 intact. 



After destruction of the anterb-lateral pole of both hemispheres 

 this animal gave no evidence of retention. 



Seventeen animals are reported in this series. The extent 

 of injury and the degree of retention is given in the following 

 table. 



After partial or complete destruction of the frontal poles of 

 both hemispheres some of the animals retained the habit, others 

 lost it, and of these some reacquired it after training and others 



