CHAPTER 

 XII 



ANASTOMOTIC NETS COMBATING NOISE* 



Warren S. McGulloch, M.D. 



We 



E INHERITED from Greek medicine a recognition that 

 knowledge depends in some manner upon a mixture of a knower 

 and the known. The Fathers of Medicine supposed that this mixing 

 took place locally in the anastomotic veins and was carried by 

 the blood to the general mixture in the heart. Except for a few 

 chemical messengers like hormones, we have abandoned this 

 cardiocentric theory of knowledge for a cephalocentric one. We 

 have replaced their mixture of substances with an interaction of 

 signals, but have retained the essentially anastomotic quality of 

 the net. In fact, we conceive our nervous system to be so anasto- 

 motic that every efferent peripheral neuron can be affected over 

 a multiplicity of paths by every afferent peripheral neuron. 



For the purposes of this paper, I shall ignore all other sources 

 of reliability in the process of perception. I mean such things as: 

 1) closed loops of reflexive and regulatory mechanisms; 2) use of 

 topological mapping to preserve local sign; 3) redundancy of code 

 that is inherent in the repetition rate characteristic of those nervous 

 structures that determine posture and motion; and 4) autocor- 

 relative functions of the cerebellum that are used to raise signals 

 out of a background of noise. 



I shall say nothing about evolution, adaptation, learning, or 

 repair. My reason is this: The nervous system is state-determined; 

 that is, at any one time its change into another state is determined 



*This work was supported in part by the U.S. Army Signal Corps, the Air Force 

 Office of Scientific Research, and the Office of Naval Research; in pai-t by the National 

 Institutes of Health Grant B-1865, (C3); and in part by the U.S. Air Force, Aero- 

 nautical Systems Division, under Contract AF33(616)-7783. 



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