43^ 



BRAIN MECHANISMS AND LEARNING 



VOLTAGE SERIES AT 100 MSEC. INTERVAL 



One voltage series was made when the interval between stimuli was 

 100 msec. In Fig. 7 are represented the results obtained. It can be seen that 

 at 2 volts there was no modification; at 3 volts the negative potential 

 began to decrease and the positive one remained unchanged. At 4 and 5 

 volts the dimniution of the negative potential was more marked and no 

 change was observed on the positive potential. 



2v 



3v 



4v 



5v 



Fig. 7 

 Voltage series at loo msec, interval. Time 200 cps. Calibration: 500 [iV. 



VOLTAGE SERIES AT 50 MSEC. INTERVAL 



The same voltage series was repeated at 50 msec, interval between 

 stimuli and the results arc summarized in Fig. 8. It can be observed that at 

 2 volts there is already a decrease oi the negative potential which is more 

 marked at 3 and 5 volts. Regarding the positive wave a little increase was 

 seen. 



In all the previous experiments the negative wave underwent significant 

 changes, while the positive wave remained almost unchanged. Only when 



