252 BRAIN MECHANISMS AND LEARNING 



LA-R Triol I Robbii m3 4-28 58 



RA-R 





— L_ 



LVis (Bp) 

 RVis (Bp) 





Triol 19 



^N/w^vYVW^^V 



'- — - — ■ — -~--Ay\/\jyyyif"//v'^/\/^ v — « — ^ 



Trial 42 



'^f^{,'{j^yWiJVM\lJ'/'^ 



-s>A'u\AAnvjWVV.^^/VV\'\,V% 



Fig. I 



Sample conditioning trials illustrating responses before 

 conditioning (Trial i), repetitive response (Trial 19), 

 and localized desynchronization of Stage III (Trial 42). 

 Desynchronization is barely visible because of the low 

 amplifier gain necessitated by simultaneous tape re- 

 cording. The repetitive response of Stage II, however, 

 is clearly evident. Equally evident is the lack of re- 

 petitive response in Stage III. The signal channel (S) 

 indicates by the first deflection the onset of the con- 

 ditional acoustic signal. A photoelectrical cell records 

 the light flashes superimposed on the signal channel 

 and the final deflection indicates the cessation of tone. 

 The onset of the tone precedes the light by 2 seconds 

 and is continuous with it for a further 5 seconds, both 

 signals going off" together. This convention is followed 

 in the succeeding figure as well. Calibration: 200 

 microvolts and i second. Channel designations are 

 as follows: left auditory to reference, right auditory to 

 reference, signal, left visual (bipolar), right visual 

 (bipolar), left visual to right visual, left visual to 

 reference, right visual to reference. The electrodes 

 were implanted over the respective cortical regions 

 prior to this examination. The animal is unanaesthctized 

 but restrained in a comfortable hammock. (From 

 Morrell, Barlow, and Brazier. Analysis of conditioned 

 repetitive response by means of the average response 

 computor. Biolo^icnl Psych'uitry. In Press.) 



