E. A. ASRATYAN II3 



aspect of cerebral function. It may tnid its simplest, its most experimentally 

 attackable form in the apparent ordering in time of the conditioned stimulus and 

 unconditioned stimulus. I was going to ask Professor Asratyan what speculations 

 he was making about possible neuronal action that might explain this. It seems to 

 me that Protcssor Fessard's point is excellent but yet there is the turther problem 

 that conditioning is not good unless there is some overlap. It is as it the line had to be 

 busy to a certain extent, or in certain circumstances. 



I would like to say also that I found the paper very interesting in the study of 

 relatively unimportant, biologically unimportant, stimulations. So much of human 

 behaviour is composed of reactions to biologically neutral stimuli, or very nearly 

 neutral. 



Asratyan. First of all I should like to remind you that we are quoting from our 

 data. In the case of stereotyped sec]uences ot application ot the stimulus the signifi- 

 cance of these two conditioned connections is different. Dr Konorski also men- 

 tioned this in his remarks that direct conditioning in all cases is much stronger and 

 steadier and more regular than backward conditioning. This illustrates the bio- 

 logical differences between these connections and the significance of the sequence 

 of combination. How does one explain thisf Originally both nervous points of 

 both stimuli are equally stimulated, however once the connection is established 

 and the stimuli inverted, one point, namely the second point, receives stimuli from 

 two sources, whereas the other receives only its original stimulus. This is the reason 

 for the reinforcement of forward conditioning and the difficulty of backward 

 conditioning. 



In answer to vour second question, in cases ot biologically weak stimuli, as tor 

 example in cases when we combined two so-called indifferent reflexes, giving rise 

 to the elaboration of weak two-wav conditioned reffex, these reflexes disappear 

 very rapidly. Occasionally in our cases we have been able to prolong their duration. 

 Why these conditioned weak reflexes disappear we don't know. Our theory, our 

 'fantasy', is that it is due to the lower threshold level of excitation, to the small 

 number of cells activated in both coupled nervous points during the elaboration of 

 reflexes. As a result of the activation of such reflexes, their weak connections easily 

 become exhausted and fatigued and soon disappear. A strong stimulus would call 

 into play a larger number ot cells and consequently a steady conditioned reflex is 

 elaborated. 



