INCOMPREHENSIBLES — CORNER 247 



The trace of any activity is not an isolated connection between sensory and 

 motor elements. It is tied in w ith the whole complex of spacial and temporal 

 axes of nervous activity. Tlie space and time coordinates can, I believe, be main- 

 tained by . . . rhythmic discharges which pervade the entire brain, influencing 

 the organization of activity anywhere. Within a functional area the cells acquire 

 the capacity to react in certain definite patterns. . . . The characteristics of the 

 nervous network are such that when it is subjected to any pattern of excitation, 

 it may develop a pattern of activity, reduplicated throughout an entire functional 

 area by spread of excitations. . . . x\ll the cells of the brain must be in almost 

 constant activity, either firing or actively inhibited. . . . The learning process 

 must consist of the attunement of the elements of a complex system in such a 

 way that a particular combination of cells responds more readily than before the 

 experience. 



The mental patterns of learning and of directed response, of which 

 Lashley writes, are set up in an apparatus which in man consists of 

 billions of neurones, interconnected through innumerable channels. 

 The organ in which these patterns are stored is subject to excitation 

 from outside through five senses, each of them so critically sensitive 

 that a touch, a whiff of odor, can suddenly revive a whole chapter of 

 the past — one chapter for me, another for you ; one syllable heard may 

 set off a torrent of emotion or activity. The mechanism is also sensitive 

 to stimulation from within itself by stored memories, by organic sen- 

 sations, by local subthreshold fluctuations of physical states through- 

 out the body. Surgeons sometimes have an opportunity to stimulate 

 the brain directly in a patient who is conscious and cooperative during 

 an operation under local anesthesia. Dr. Wilder Penfield thus found 

 that electrical stimulation at a single point of the cortex can elicit 

 elaborate memories of things seen or heard. A big electronic com- 

 putor has a bank of keys like a pipe organ; who can estimate the 

 number of keys to the human mind, within the body and on the sur- 

 face of its sensorium, through which impulses are thrown into one 

 circuit or another, to start who knows how many oscillations in the 

 next circuit, and the next? Nervous and mental operations involve, 

 however, more than mere spread and flow of impulses. There are 

 slowing and blocking resistors ; there are shunts and diversions. There 

 are circuits that operate to cut out other circuits, or to cut them in, 

 or steady their oscillations. The elements of these circuits, moreover, 

 are not copper wires, metal switches, and electronic tubes. The con- 

 ducting threads, as well as the whole organism they interconnect, are 

 made up of elaborate and unstable chemical substances, very critically 

 responsive to changing conditions. 



Their hookup into a vast network is also unstable and critically 

 responsive. Integration of an organism so that this multiplex sys- 

 tem will behave in a measurably constant way calls for all sorts of 

 internal controls — the homeostatic regulators that Walter Cannon 

 wrote about — and in higher animals on the behavioral level it demands 



326511— B5 17 



