KAO LIANG CHOW 525 



AsRATYAN. I think that some of our data pubhshed in 1937 in Russia may be of 

 interest to Dr Chow. That is why I want Dr Chow to become acquainted with 

 these facts. We divided the brain cortex of the dog into three isolated parts, 

 namely, the frontal, occipital and temporal parts, by surgical extirpation of ribbons 

 of cortical tissue between main parts of brain cortex. Let me show the operation 

 schematically on the blackboard. We cut only the cortex tissue, but as it was 

 shown later by histological control degeneration of subcortical white tissue took 

 place also. So, these cortical parts were iully isolated from each other and con- 

 nected with each other only through subcortical structures. We were able to 

 elaborate conditioned defensive motor reflexes to the visual as well as to the audi- 

 tory stimulus. After repeated cortical operation during which wc extirpated cither 

 the isolated occipital or temporal regions, the visual or auditory reflexes were 

 correspondingly abolished. 



Chow (in answer to a question from Dr Naquet). In this expernncnt the only 

 control I had w^as to stimulate the visual area either uni- or bilaterally or one 

 electrode on each occipital area and to test on retention. I have not tested on 

 learning. Whether you tested immediatelv after or during stimulation of the visual 

 areas there is no detrimental effect on retention ot the visual discriminations. 



Segundo. In support ot Dr Buser's defence ot the usctulness ot electrographic 

 recording in the study of learning, I would mention that, in our experience, the 

 EEG provided more sensitive criteria than pertormance. First, EEC effects appeared 

 earlier than behavioural effects during establishment and disappeared later during 

 extinction of learned responses. Secondly, when studying very wild cats, animals 

 gave little behavioural evidence of 'learning' but electrographicallv yielded 

 obvious siuns of conditioning. 



