CEREBRAL FUNCTION IN THE RAT 



119 



After the destruction of somewhat more than the anterodorsal 

 third of the cortex, together with a large area on the right occipital 

 lobe, this animal showed no detectable abnormality in behavior 

 or in the rate of habit formation. 



Experiment 36. A transverse opening 10 by 8 mm. was made 

 in the calvarium of a small female rat, 115 days old, and trans- 

 verse and longitudinal incisions were made in the cortex to as 

 great a depth as possible. Recovery was rapid and without 

 appreciable motor disturbance. She ate alone from the first 

 and seemed practically normal in behavior except for a com- 

 plete indifference to other animals of the same 'or opposite sex. 



Training in the simple maze was begun 12 days after the 

 operation. The habit of going to the right was perfected in 

 fifty trials. She had, apparently, an initial preference for the 

 right side of the maze. Training to break up this and to estab- 

 lish the habit of going to the left was then started and one hun- 

 dred and twenty trials were required before ten successive error- 

 less trials were made. The records of time and errors are given 

 in table 2. 



TABLE 2 

 Rate of learning for rat described in experiment 36 



The rat was autopsied 40 days after the operation. Micro- 

 scopical examination of the brain shows (plates I and II, fig. 36) : 



