D. O. HEBB 51 



many times in connection with this, that extensive studies have been done by Beck 

 along the same hnes, showing the dropping out of neurones. 



Chow. I think that the problem Dr Hebb proposes is a very important one. 

 What kind of mechanism can produce such effects that one exposure will redirect 

 nerve impulses in a certain direction? 



I would like to point out Lashley's notion that maybe you are creating some 

 kind of field effect by your repeating the digits. Therefore, in essence you may 

 create a DC potential gradient there, as if you had applied an external DC current. 

 This presumably will modify all your neuronal excitability and will make your 

 impulse flow easily in one direction. I think this may be a possible mechanism. 



Hebb. It appears to me that we are dealing very often, not with the activity of all 

 neurones in one topographical area as against the neurones in another topographical 

 area but with selective fictors among neurones interlinked with one another. It is 

 very diflicult to conceive a functional value from a DC field that is more extensive 

 than a single neurone or 2 or 3 neurones. This is my problem. 



