WHAT WE DO WITH OUR BRAINS 7 



is not that of a simple geometric progression, for the 

 lines of connection cross in all imaginable patterns 

 and any one of the nine thousand million cortical 

 neurons may be represented in very many of the 

 possible associational patterns. To recur to our 

 analogy of a genealogical tree of a million families, 

 the family lines do not run on quite independently 

 of one another, but by intermarriage each family tree 

 is related with all of the others. 



Upon activation of the visual cortical field by 

 the sight of the litter of the day's work upon my 

 study table, associational processes are immediately 

 set up within the cortex and each of the million 

 excited cells of the visual area activates at least ten 

 others, and each of these, in turn, ten others, and 

 again on and on as long as the cortical process con- 

 tinues. And any particular cortical neuron may be 

 repeatedly activated in different associational pat- 

 terns, and the range of variety of these possible 

 combinations cannot be exactly formulated in mathe- 

 matical terms. For practical purposes it may be re- 

 garded as approaching infinity. 



On the basis of the known structure of the cortex, 

 the following computation may be regarded as a 

 conservative statement of the number of inter- 

 cellular connections that are anatomically present and 

 available for use in a short series of cortical associa- 

 tional processes. Starting again with a million (10^) 

 cortical neurons of the visual area simultaneously ex- 



